content: /*
   * Copyright (C) 2010 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package android.app;
  
  import android.animation.Animator;
  import android.animation.AnimatorInflater;
  import android.animation.AnimatorListenerAdapter;
  import android.animation.AnimatorSet;
  import android.animation.PropertyValuesHolder;
  import android.animation.ValueAnimator;
  import android.annotation.UnsupportedAppUsage;
  import android.content.Context;
  import android.content.pm.ApplicationInfo;
  import android.content.res.Configuration;
  import android.content.res.Resources.NotFoundException;
  import android.content.res.TypedArray;
  import android.os.Build;
  import android.os.Bundle;
  import android.os.Debug;
  import android.os.Looper;
  import android.os.Parcel;
  import android.os.Parcelable;
  import android.util.ArraySet;
  import android.util.AttributeSet;
  import android.util.DebugUtils;
  import android.util.Log;
  import android.util.LogWriter;
  import android.util.Pair;
  import android.util.SparseArray;
  import android.util.SuperNotCalledException;
  import android.view.LayoutInflater;
  import android.view.Menu;
  import android.view.MenuInflater;
  import android.view.MenuItem;
  import android.view.View;
  import android.view.ViewGroup;
  
  import com.android.internal.util.FastPrintWriter;
  
  import java.io.FileDescriptor;
  import java.io.PrintWriter;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.List;
  import java.util.concurrent.CopyOnWriteArrayList;
  
  /**
   * Interface for interacting with {@link Fragment} objects inside of an
   * {@link Activity}
   *
   * <div class="special reference">
   * <h3>Developer Guides</h3>
   * <p>For more information about using fragments, read the
   * <a href="{@docRoot}guide/components/fragments.html">Fragments</a> developer guide.</p>
   * </div>
   *
   * While the FragmentManager API was introduced in
   * {@link android.os.Build.VERSION_CODES#HONEYCOMB}, a version of the API
   * at is also available for use on older platforms through
   * {@link android.support.v4.app.FragmentActivity}.  See the blog post
   * <a href="http://android-developers.blogspot.com/2011/03/fragments-for-all.html">
   * Fragments For All</a> for more details.
   *
   * @deprecated Use the <a href="{@docRoot}tools/extras/support-library.html">Support Library</a>
   *      {@link android.support.v4.app.FragmentManager} for consistent behavior across all devices
   *      and access to <a href="{@docRoot}topic/libraries/architecture/lifecycle.html">Lifecycle</a>.
   */
  @Deprecated
  public abstract class FragmentManager {
      /**
       * Representation of an entry on the fragment back stack, as created
       * with {@link FragmentTransaction#addToBackStack(String)
       * FragmentTransaction.addToBackStack()}.  Entries can later be
       * retrieved with {@link FragmentManager#getBackStackEntryAt(int)
       * FragmentManager.getBackStackEntryAt()}.
       *
       * <p>Note that you should never hold on to a BackStackEntry object;
       * the identifier as returned by {@link #getId} is the only thing that
       * will be persisted across activity instances.
       *
       * @deprecated Use the <a href="{@docRoot}tools/extras/support-library.html">
       *      Support Library</a> {@link android.support.v4.app.FragmentManager.BackStackEntry}
       */
      @Deprecated
      public interface BackStackEntry {
          /**
           * Return the unique identifier for the entry.  This is the only
           * representation of the entry that will persist across activity
           * instances.
           */
          public int getId();
  
          /**
           * Get the name that was supplied to
           * {@link FragmentTransaction#addToBackStack(String)
           * FragmentTransaction.addToBackStack(String)} when creating this entry.
           */
          public String getName();
  
          /**
           * Return the full bread crumb title resource identifier for the entry,
           * or 0 if it does not have one.
           */
          public int getBreadCrumbTitleRes();
  
          /**
           * Return the short bread crumb title resource identifier for the entry,
           * or 0 if it does not have one.
           */
          public int getBreadCrumbShortTitleRes();
  
          /**
           * Return the full bread crumb title for the entry, or null if it
           * does not have one.
           */
          public CharSequence getBreadCrumbTitle();
  
          /**
           * Return the short bread crumb title for the entry, or null if it
           * does not have one.
           */
          public CharSequence getBreadCrumbShortTitle();
      }
  
      /**
       * Interface to watch for changes to the back stack.
       *
       * @deprecated Use the <a href="{@docRoot}tools/extras/support-library.html">
       *      Support Library</a>
       *      {@link android.support.v4.app.FragmentManager.OnBackStackChangedListener}
       */
      @Deprecated
      public interface OnBackStackChangedListener {
          /**
           * Called whenever the contents of the back stack change.
           */
          public void onBackStackChanged();
      }
  
      /**
       * Start a series of edit operations on the Fragments associated with
       * this FragmentManager.
       * 
       * <p>Note: A fragment transaction can only be created/committed prior
       * to an activity saving its state.  If you try to commit a transaction
       * after {@link Activity#onSaveInstanceState Activity.onSaveInstanceState()}
       * (and prior to a following {@link Activity#onStart Activity.onStart}
       * or {@link Activity#onResume Activity.onResume()}, you will get an error.
       * This is because the framework takes care of saving your current fragments
       * in the state, and if changes are made after the state is saved then they
       * will be lost.</p>
       */
      public abstract FragmentTransaction beginTransaction();
  
      /** @hide -- remove once prebuilts are in. */
      @Deprecated
      public FragmentTransaction openTransaction() {
          return beginTransaction();
      }
      
      /**
       * After a {@link FragmentTransaction} is committed with
       * {@link FragmentTransaction#commit FragmentTransaction.commit()}, it
       * is scheduled to be executed asynchronously on the process's main thread.
       * If you want to immediately executing any such pending operations, you
       * can call this function (only from the main thread) to do so.  Note that
       * all callbacks and other related behavior will be done from within this
       * call, so be careful about where this is called from.
       * <p>
       * This also forces the start of any postponed Transactions where
       * {@link Fragment#postponeEnterTransition()} has been called.
       *
       * @return Returns true if there were any pending transactions to be
       * executed.
       */
      public abstract boolean executePendingTransactions();
  
      /**
       * Finds a fragment that was identified by the given id either when inflated
       * from XML or as the container ID when added in a transaction.  This first
       * searches through fragments that are currently added to the manager's
       * activity; if no such fragment is found, then all fragments currently
       * on the back stack associated with this ID are searched.
       * @return The fragment if found or null otherwise.
       */
      public abstract Fragment findFragmentById(int id);
  
      /**
       * Finds a fragment that was identified by the given tag either when inflated
       * from XML or as supplied when added in a transaction.  This first
       * searches through fragments that are currently added to the manager's
       * activity; if no such fragment is found, then all fragments currently
       * on the back stack are searched.
       * @return The fragment if found or null otherwise.
       */
      public abstract Fragment findFragmentByTag(String tag);
  
      /**
       * Flag for {@link #popBackStack(String, int)}
       * and {@link #popBackStack(int, int)}: If set, and the name or ID of
       * a back stack entry has been supplied, then all matching entries will
       * be consumed until one that doesn't match is found or the bottom of
       * the stack is reached.  Otherwise, all entries up to but not including that entry
       * will be removed.
       */
      public static final int POP_BACK_STACK_INCLUSIVE = 1<<0;
  
      /**
       * Pop the top state off the back stack.  This function is asynchronous -- it
       * enqueues the request to pop, but the action will not be performed until the
       * application returns to its event loop.
       */
      public abstract void popBackStack();
  
      /**
       * Like {@link #popBackStack()}, but performs the operation immediately
       * inside of the call.  This is like calling {@link #executePendingTransactions()}
       * afterwards without forcing the start of postponed Transactions.
       * @return Returns true if there was something popped, else false.
       */
      public abstract boolean popBackStackImmediate();
  
      /**
       * Pop the last fragment transition from the manager's fragment
       * back stack.  If there is nothing to pop, false is returned.
       * This function is asynchronous -- it enqueues the
       * request to pop, but the action will not be performed until the application
       * returns to its event loop.
       * 
       * @param name If non-null, this is the name of a previous back state
       * to look for; if found, all states up to that state will be popped.  The
       * {@link #POP_BACK_STACK_INCLUSIVE} flag can be used to control whether
       * the named state itself is popped. If null, only the top state is popped.
       * @param flags Either 0 or {@link #POP_BACK_STACK_INCLUSIVE}.
       */
      public abstract void popBackStack(String name, int flags);
  
      /**
       * Like {@link #popBackStack(String, int)}, but performs the operation immediately
       * inside of the call.  This is like calling {@link #executePendingTransactions()}
       * afterwards without forcing the start of postponed Transactions.
       * @return Returns true if there was something popped, else false.
       */
      public abstract boolean popBackStackImmediate(String name, int flags);
  
      /**
       * Pop all back stack states up to the one with the given identifier.
       * This function is asynchronous -- it enqueues the
       * request to pop, but the action will not be performed until the application
       * returns to its event loop.
       * 
       * @param id Identifier of the stated to be popped. If no identifier exists,
       * false is returned.
       * The identifier is the number returned by
       * {@link FragmentTransaction#commit() FragmentTransaction.commit()}.  The
       * {@link #POP_BACK_STACK_INCLUSIVE} flag can be used to control whether
       * the named state itself is popped.
       * @param flags Either 0 or {@link #POP_BACK_STACK_INCLUSIVE}.
       */
      public abstract void popBackStack(int id, int flags);
  
      /**
       * Like {@link #popBackStack(int, int)}, but performs the operation immediately
       * inside of the call.  This is like calling {@link #executePendingTransactions()}
       * afterwards without forcing the start of postponed Transactions.
       * @return Returns true if there was something popped, else false.
       */
      public abstract boolean popBackStackImmediate(int id, int flags);
  
      /**
       * Return the number of entries currently in the back stack.
       */
      public abstract int getBackStackEntryCount();
  
      /**
       * Return the BackStackEntry at index <var>index</var> in the back stack;
       * where the item on the bottom of the stack has index 0.
       */
      public abstract BackStackEntry getBackStackEntryAt(int index);
  
      /**
       * Add a new listener for changes to the fragment back stack.
       */
      public abstract void addOnBackStackChangedListener(OnBackStackChangedListener listener);
  
      /**
       * Remove a listener that was previously added with
       * {@link #addOnBackStackChangedListener(OnBackStackChangedListener)}.
       */
      public abstract void removeOnBackStackChangedListener(OnBackStackChangedListener listener);
  
      /**
       * Put a reference to a fragment in a Bundle.  This Bundle can be
       * persisted as saved state, and when later restoring
       * {@link #getFragment(Bundle, String)} will return the current
       * instance of the same fragment.
       *
       * @param bundle The bundle in which to put the fragment reference.
       * @param key The name of the entry in the bundle.
       * @param fragment The Fragment whose reference is to be stored.
       */
      public abstract void putFragment(Bundle bundle, String key, Fragment fragment);
  
      /**
       * Retrieve the current Fragment instance for a reference previously
       * placed with {@link #putFragment(Bundle, String, Fragment)}.
       *
       * @param bundle The bundle from which to retrieve the fragment reference.
       * @param key The name of the entry in the bundle.
       * @return Returns the current Fragment instance that is associated with
       * the given reference.
       */
      public abstract Fragment getFragment(Bundle bundle, String key);
  
      /**
       * Get a list of all fragments that are currently added to the FragmentManager.
       * This may include those that are hidden as well as those that are shown.
       * This will not include any fragments only in the back stack, or fragments that
       * are detached or removed.
       * <p>
       * The order of the fragments in the list is the order in which they were
       * added or attached.
       *
       * @return A list of all fragments that are added to the FragmentManager.
       */
      public abstract List<Fragment> getFragments();
  
      /**
       * Save the current instance state of the given Fragment.  This can be
       * used later when creating a new instance of the Fragment and adding
       * it to the fragment manager, to have it create itself to match the
       * current state returned here.  Note that there are limits on how
       * this can be used:
       *
       * <ul>
       * <li>The Fragment must currently be attached to the FragmentManager.
       * <li>A new Fragment created using this saved state must be the same class
       * type as the Fragment it was created from.
       * <li>The saved state can not contain dependencies on other fragments --
       * that is it can't use {@link #putFragment(Bundle, String, Fragment)} to
       * store a fragment reference because that reference may not be valid when
       * this saved state is later used.  Likewise the Fragment's target and
       * result code are not included in this state.
       * </ul>
       *
       * @param f The Fragment whose state is to be saved.
       * @return The generated state.  This will be null if there was no
       * interesting state created by the fragment.
       */
      public abstract Fragment.SavedState saveFragmentInstanceState(Fragment f);
  
      /**
       * Returns true if the final {@link Activity#onDestroy() Activity.onDestroy()}
       * call has been made on the FragmentManager's Activity, so this instance is now dead.
       */
      public abstract boolean isDestroyed();
  
      /**
       * Registers a {@link FragmentLifecycleCallbacks} to listen to fragment lifecycle events
       * happening in this FragmentManager. All registered callbacks will be automatically
       * unregistered when this FragmentManager is destroyed.
       *
       * @param cb Callbacks to register
       * @param recursive true to automatically register this callback for all child FragmentManagers
       */
      public abstract void registerFragmentLifecycleCallbacks(FragmentLifecycleCallbacks cb,
              boolean recursive);
  
      /**
       * Unregisters a previously registered {@link FragmentLifecycleCallbacks}. If the callback
       * was not previously registered this call has no effect. All registered callbacks will be
       * automatically unregistered when this FragmentManager is destroyed.
       *
       * @param cb Callbacks to unregister
       */
      public abstract void unregisterFragmentLifecycleCallbacks(FragmentLifecycleCallbacks cb);
  
      /**
       * Return the currently active primary navigation fragment for this FragmentManager.
       *
       * <p>The primary navigation fragment's
       * {@link Fragment#getChildFragmentManager() child FragmentManager} will be called first
       * to process delegated navigation actions such as {@link #popBackStack()} if no ID
       * or transaction name is provided to pop to.</p>
       *
       * @return the fragment designated as the primary navigation fragment
       */
      public abstract Fragment getPrimaryNavigationFragment();
  
      /**
       * Print the FragmentManager's state into the given stream.
       *
       * @param prefix Text to print at the front of each line.
       * @param fd The raw file descriptor that the dump is being sent to.
       * @param writer A PrintWriter to which the dump is to be set.
       * @param args Additional arguments to the dump request.
       */
      public abstract void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args);
  
      /**
       * Control whether the framework's internal fragment manager debugging
       * logs are turned on.  If enabled, you will see output in logcat as
       * the framework performs fragment operations.
       */
      public static void enableDebugLogging(boolean enabled) {
          FragmentManagerImpl.DEBUG = enabled;
      }
  
      /**
       * Invalidate the attached activity's options menu as necessary.
       * This may end up being deferred until we move to the resumed state.
       */
      public void invalidateOptionsMenu() { }
  
      /**
       * Returns {@code true} if the FragmentManager's state has already been saved
       * by its host. Any operations that would change saved state should not be performed
       * if this method returns true. For example, any popBackStack() method, such as
       * {@link #popBackStackImmediate()} or any FragmentTransaction using
       * {@link FragmentTransaction#commit()} instead of
       * {@link FragmentTransaction#commitAllowingStateLoss()} will change
       * the state and will result in an error.
       *
       * @return true if this FragmentManager's state has already been saved by its host
       */
      public abstract boolean isStateSaved();
  
      /**
       * Callback interface for listening to fragment state changes that happen
       * within a given FragmentManager.
       *
       * @deprecated Use the <a href="{@docRoot}tools/extras/support-library.html">
       *      Support Library</a>
       *      {@link android.support.v4.app.FragmentManager.FragmentLifecycleCallbacks}
       */
      @Deprecated
      public abstract static class FragmentLifecycleCallbacks {
          /**
           * Called right before the fragment's {@link Fragment#onAttach(Context)} method is called.
           * This is a good time to inject any required dependencies for the fragment before any of
           * the fragment's lifecycle methods are invoked.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           * @param context Context that the Fragment is being attached to
           */
          public void onFragmentPreAttached(FragmentManager fm, Fragment f, Context context) {}
  
          /**
           * Called after the fragment has been attached to its host. Its host will have had
           * <code>onAttachFragment</code> called before this call happens.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           * @param context Context that the Fragment was attached to
           */
          public void onFragmentAttached(FragmentManager fm, Fragment f, Context context) {}
  
          /**
           * Called right before the fragment's {@link Fragment#onCreate(Bundle)} method is called.
           * This is a good time to inject any required dependencies or perform other configuration
           * for the fragment.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           * @param savedInstanceState Saved instance bundle from a previous instance
           */
          public void onFragmentPreCreated(FragmentManager fm, Fragment f,
                  Bundle savedInstanceState) {}
  
          /**
           * Called after the fragment has returned from the FragmentManager's call to
           * {@link Fragment#onCreate(Bundle)}. This will only happen once for any given
           * fragment instance, though the fragment may be attached and detached multiple times.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           * @param savedInstanceState Saved instance bundle from a previous instance
           */
          public void onFragmentCreated(FragmentManager fm, Fragment f, Bundle savedInstanceState) {}
  
          /**
           * Called after the fragment has returned from the FragmentManager's call to
           * {@link Fragment#onActivityCreated(Bundle)}. This will only happen once for any given
           * fragment instance, though the fragment may be attached and detached multiple times.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           * @param savedInstanceState Saved instance bundle from a previous instance
           */
          public void onFragmentActivityCreated(FragmentManager fm, Fragment f,
                  Bundle savedInstanceState) {}
  
          /**
           * Called after the fragment has returned a non-null view from the FragmentManager's
           * request to {@link Fragment#onCreateView(LayoutInflater, ViewGroup, Bundle)}.
           *
           * @param fm Host FragmentManager
           * @param f Fragment that created and owns the view
           * @param v View returned by the fragment
           * @param savedInstanceState Saved instance bundle from a previous instance
           */
          public void onFragmentViewCreated(FragmentManager fm, Fragment f, View v,
                  Bundle savedInstanceState) {}
  
          /**
           * Called after the fragment has returned from the FragmentManager's call to
           * {@link Fragment#onStart()}.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           */
          public void onFragmentStarted(FragmentManager fm, Fragment f) {}
  
          /**
           * Called after the fragment has returned from the FragmentManager's call to
           * {@link Fragment#onResume()}.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           */
          public void onFragmentResumed(FragmentManager fm, Fragment f) {}
  
          /**
           * Called after the fragment has returned from the FragmentManager's call to
           * {@link Fragment#onPause()}.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           */
          public void onFragmentPaused(FragmentManager fm, Fragment f) {}
  
          /**
           * Called after the fragment has returned from the FragmentManager's call to
           * {@link Fragment#onStop()}.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           */
          public void onFragmentStopped(FragmentManager fm, Fragment f) {}
  
          /**
           * Called after the fragment has returned from the FragmentManager's call to
           * {@link Fragment#onSaveInstanceState(Bundle)}.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           * @param outState Saved state bundle for the fragment
           */
          public void onFragmentSaveInstanceState(FragmentManager fm, Fragment f, Bundle outState) {}
  
          /**
           * Called after the fragment has returned from the FragmentManager's call to
           * {@link Fragment#onDestroyView()}.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           */
          public void onFragmentViewDestroyed(FragmentManager fm, Fragment f) {}
  
          /**
           * Called after the fragment has returned from the FragmentManager's call to
           * {@link Fragment#onDestroy()}.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           */
          public void onFragmentDestroyed(FragmentManager fm, Fragment f) {}
  
          /**
           * Called after the fragment has returned from the FragmentManager's call to
           * {@link Fragment#onDetach()}.
           *
           * @param fm Host FragmentManager
           * @param f Fragment changing state
           */
          public void onFragmentDetached(FragmentManager fm, Fragment f) {}
      }
  }
  
  final class FragmentManagerState implements Parcelable {
      FragmentState[] mActive;
      int[] mAdded;
      BackStackState[] mBackStack;
      int mPrimaryNavActiveIndex = -1;
      int mNextFragmentIndex;
      
      public FragmentManagerState() {
      }
      
      public FragmentManagerState(Parcel in) {
          mActive = in.createTypedArray(FragmentState.CREATOR);
          mAdded = in.createIntArray();
          mBackStack = in.createTypedArray(BackStackState.CREATOR);
          mPrimaryNavActiveIndex = in.readInt();
          mNextFragmentIndex = in.readInt();
      }
      
      public int describeContents() {
          return 0;
      }
  
      public void writeToParcel(Parcel dest, int flags) {
          dest.writeTypedArray(mActive, flags);
          dest.writeIntArray(mAdded);
          dest.writeTypedArray(mBackStack, flags);
          dest.writeInt(mPrimaryNavActiveIndex);
          dest.writeInt(mNextFragmentIndex);
      }
      
      public static final @android.annotation.NonNull Parcelable.Creator<FragmentManagerState> CREATOR
              = new Parcelable.Creator<FragmentManagerState>() {
          public FragmentManagerState createFromParcel(Parcel in) {
              return new FragmentManagerState(in);
          }
          
          public FragmentManagerState[] newArray(int size) {
              return new FragmentManagerState[size];
          }
      };
  }
  
  /**
   * Container for fragments associated with an activity.
   */
  final class FragmentManagerImpl extends FragmentManager implements LayoutInflater.Factory2 {
      static boolean DEBUG = false;
      static final String TAG = "FragmentManager";
      
      static final String TARGET_REQUEST_CODE_STATE_TAG = "android:target_req_state";
      static final String TARGET_STATE_TAG = "android:target_state";
      static final String VIEW_STATE_TAG = "android:view_state";
      static final String USER_VISIBLE_HINT_TAG = "android:user_visible_hint";
  
      static class AnimateOnHWLayerIfNeededListener implements Animator.AnimatorListener {
          private boolean mShouldRunOnHWLayer = false;
          private View mView;
          public AnimateOnHWLayerIfNeededListener(final View v) {
              if (v == null) {
                  return;
              }
              mView = v;
          }
  
          @Override
          public void onAnimationStart(Animator animation) {
              mShouldRunOnHWLayer = shouldRunOnHWLayer(mView, animation);
              if (mShouldRunOnHWLayer) {
                  mView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
              }
          }
  
          @Override
          public void onAnimationEnd(Animator animation) {
              if (mShouldRunOnHWLayer) {
                  mView.setLayerType(View.LAYER_TYPE_NONE, null);
              }
              mView = null;
              animation.removeListener(this);
          }
  
          @Override
          public void onAnimationCancel(Animator animation) {
  
          }
  
          @Override
          public void onAnimationRepeat(Animator animation) {
  
          }
      }
  
      ArrayList<OpGenerator> mPendingActions;
      boolean mExecutingActions;
  
      int mNextFragmentIndex = 0;
      @UnsupportedAppUsage
      SparseArray<Fragment> mActive;
      @UnsupportedAppUsage
      final ArrayList<Fragment> mAdded = new ArrayList<>();
      ArrayList<BackStackRecord> mBackStack;
      ArrayList<Fragment> mCreatedMenus;
      
      // Must be accessed while locked.
      ArrayList<BackStackRecord> mBackStackIndices;
      ArrayList<Integer> mAvailBackStackIndices;
  
      ArrayList<OnBackStackChangedListener> mBackStackChangeListeners;
      final CopyOnWriteArrayList<Pair<FragmentLifecycleCallbacks, Boolean>>
              mLifecycleCallbacks = new CopyOnWriteArrayList<>();
  
      int mCurState = Fragment.INITIALIZING;
      FragmentHostCallback<?> mHost;
      FragmentContainer mContainer;
      Fragment mParent;
      Fragment mPrimaryNav;
      
      boolean mNeedMenuInvalidate;
      @UnsupportedAppUsage
      boolean mStateSaved;
      boolean mDestroyed;
      String mNoTransactionsBecause;
      boolean mHavePendingDeferredStart;
  
      // Temporary vars for removing redundant operations in BackStackRecords:
      ArrayList<BackStackRecord> mTmpRecords;
      ArrayList<Boolean> mTmpIsPop;
      ArrayList<Fragment> mTmpAddedFragments;
  
      // Temporary vars for state save and restore.
      Bundle mStateBundle = null;
      SparseArray<Parcelable> mStateArray = null;
  
      // Postponed transactions.
      ArrayList<StartEnterTransitionListener> mPostponedTransactions;
  
      // Prior to O, we allowed executing transactions during fragment manager state changes.
      // This is dangerous, but we want to keep from breaking old applications.
      boolean mAllowOldReentrantBehavior;
  
      // Saved FragmentManagerNonConfig during saveAllState() and cleared in noteStateNotSaved()
      FragmentManagerNonConfig mSavedNonConfig;
  
      Runnable mExecCommit = new Runnable() {
          @Override
          public void run() {
              execPendingActions();
          }
      };
  
      private void throwException(RuntimeException ex) {
          Log.e(TAG, ex.getMessage());
          LogWriter logw = new LogWriter(Log.ERROR, TAG);
          PrintWriter pw = new FastPrintWriter(logw, false, 1024);
          if (mHost != null) {
              Log.e(TAG, "Activity state:");
              try {
                  mHost.onDump("  ", null, pw, new String[] { });
              } catch (Exception e) {
                  pw.flush();
                  Log.e(TAG, "Failed dumping state", e);
              }
          } else {
              Log.e(TAG, "Fragment manager state:");
              try {
                  dump("  ", null, pw, new String[] { });
              } catch (Exception e) {
                  pw.flush();
                  Log.e(TAG, "Failed dumping state", e);
              }
          }
          pw.flush();
          throw ex;
      }
  
      static boolean modifiesAlpha(Animator anim) {
          if (anim == null) {
              return false;
          }
          if (anim instanceof ValueAnimator) {
              ValueAnimator valueAnim = (ValueAnimator) anim;
              PropertyValuesHolder[] values = valueAnim.getValues();
              for (int i = 0; i < values.length; i++) {
                  if (("alpha").equals(values[i].getPropertyName())) {
                      return true;
                  }
              }
          } else if (anim instanceof AnimatorSet) {
              List<Animator> animList = ((AnimatorSet) anim).getChildAnimations();
              for (int i = 0; i < animList.size(); i++) {
                  if (modifiesAlpha(animList.get(i))) {
                      return true;
                  }
              }
          }
          return false;
      }
  
      static boolean shouldRunOnHWLayer(View v, Animator anim) {
          if (v == null || anim == null) {
              return false;
          }
          return v.getLayerType() == View.LAYER_TYPE_NONE
                  && v.hasOverlappingRendering()
                  && modifiesAlpha(anim);
      }
  
      /**
       * Sets the to be animated view on hardware layer during the animation.
       */
      private void setHWLayerAnimListenerIfAlpha(final View v, Animator anim) {
          if (v == null || anim == null) {
              return;
          }
          if (shouldRunOnHWLayer(v, anim)) {
              anim.addListener(new AnimateOnHWLayerIfNeededListener(v));
          }
      }
  
      @Override
      public FragmentTransaction beginTransaction() {
          return new BackStackRecord(this);
      }
  
      @Override
      public boolean executePendingTransactions() {
          boolean updates = execPendingActions();
          forcePostponedTransactions();
          return updates;
      }
  
      @Override
      public void popBackStack() {
          enqueueAction(new PopBackStackState(null, -1, 0), false);
      }
  
      @Override
      public boolean popBackStackImmediate() {
          checkStateLoss();
          return popBackStackImmediate(null, -1, 0);
      }
  
      @Override
      public void popBackStack(String name, int flags) {
          enqueueAction(new PopBackStackState(name, -1, flags), false);
      }
  
      @Override
      public boolean popBackStackImmediate(String name, int flags) {
          checkStateLoss();
          return popBackStackImmediate(name, -1, flags);
      }
  
      @Override
      public void popBackStack(int id, int flags) {
          if (id < 0) {
              throw new IllegalArgumentException("Bad id: " + id);
          }
          enqueueAction(new PopBackStackState(null, id, flags), false);
      }
  
      @Override
      public boolean popBackStackImmediate(int id, int flags) {
          checkStateLoss();
          if (id < 0) {
              throw new IllegalArgumentException("Bad id: " + id);
          }
          return popBackStackImmediate(null, id, flags);
      }
  
      /**
       * Used by all public popBackStackImmediate methods, this executes pending transactions and
       * returns true if the pop action did anything, regardless of what other pending
       * transactions did.
       *
       * @return true if the pop operation did anything or false otherwise.
       */
      private boolean popBackStackImmediate(String name, int id, int flags) {
          execPendingActions();
          ensureExecReady(true);
  
          if (mPrimaryNav != null // We have a primary nav fragment
                  && id < 0 // No valid id (since they're local)
                  && name == null) { // no name to pop to (since they're local)
              final FragmentManager childManager = mPrimaryNav.mChildFragmentManager;
              if (childManager != null && childManager.popBackStackImmediate()) {
                  // We did something, just not to this specific FragmentManager. Return true.
                  return true;
              }
          }
  
          boolean executePop = popBackStackState(mTmpRecords, mTmpIsPop, name, id, flags);
          if (executePop) {
              mExecutingActions = true;
              try {
                  removeRedundantOperationsAndExecute(mTmpRecords, mTmpIsPop);
              } finally {
                  cleanupExec();
              }
          }
  
          doPendingDeferredStart();
          burpActive();
          return executePop;
      }
  
      @Override
      public int getBackStackEntryCount() {
          return mBackStack != null ? mBackStack.size() : 0;
      }
  
      @Override
      public BackStackEntry getBackStackEntryAt(int index) {
          return mBackStack.get(index);
      }
  
      @Override
      public void addOnBackStackChangedListener(OnBackStackChangedListener listener) {
          if (mBackStackChangeListeners == null) {
              mBackStackChangeListeners = new ArrayList<OnBackStackChangedListener>();
          }
          mBackStackChangeListeners.add(listener);
      }
  
      @Override
      public void removeOnBackStackChangedListener(OnBackStackChangedListener listener) {
          if (mBackStackChangeListeners != null) {
              mBackStackChangeListeners.remove(listener);
          }
      }
  
      @Override
      public void putFragment(Bundle bundle, String key, Fragment fragment) {
          if (fragment.mIndex < 0) {
              throwException(new IllegalStateException("Fragment " + fragment
                      + " is not currently in the FragmentManager"));
          }
          bundle.putInt(key, fragment.mIndex);
      }
  
      @Override
      public Fragment getFragment(Bundle bundle, String key) {
          int index = bundle.getInt(key, -1);
          if (index == -1) {
              return null;
          }
          Fragment f = mActive.get(index);
          if (f == null) {
              throwException(new IllegalStateException("Fragment no longer exists for key "
                      + key + ": index " + index));
          }
          return f;
      }
  
      @Override
      public List<Fragment> getFragments() {
          if (mAdded.isEmpty()) {
              return Collections.EMPTY_LIST;
          }
          synchronized (mAdded) {
              return (List<Fragment>) mAdded.clone();
          }
      }
  
      @Override
      public Fragment.SavedState saveFragmentInstanceState(Fragment fragment) {
          if (fragment.mIndex < 0) {
              throwException(new IllegalStateException("Fragment " + fragment
                      + " is not currently in the FragmentManager"));
          }
          if (fragment.mState > Fragment.INITIALIZING) {
              Bundle result = saveFragmentBasicState(fragment);
              return result != null ? new Fragment.SavedState(result) : null;
          }
          return null;
      }
  
      @Override
      public boolean isDestroyed() {
          return mDestroyed;
      }
  
      @Override
      public String toString() {
          StringBuilder sb = new StringBuilder(128);
          sb.append("FragmentManager{");
          sb.append(Integer.toHexString(System.identityHashCode(this)));
          sb.append(" in ");
          if (mParent != null) {
              DebugUtils.buildShortClassTag(mParent, sb);
          } else {
              DebugUtils.buildShortClassTag(mHost, sb);
          }
          sb.append("}}");
          return sb.toString();
      }
  
      @Override
      public void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) {
          String innerPrefix = prefix + "    ";
  
          int N;
          if (mActive != null) {
              N = mActive.size();
              if (N > 0) {
                  writer.print(prefix); writer.print("Active Fragments in ");
                          writer.print(Integer.toHexString(System.identityHashCode(this)));
                          writer.println(":");
                  for (int i=0; i<N; i++) {
                      Fragment f = mActive.valueAt(i);
                      writer.print(prefix); writer.print("  #"); writer.print(i);
                              writer.print(": "); writer.println(f);
                      if (f != null) {
                          f.dump(innerPrefix, fd, writer, args);
                      }
                  }
              }
          }
  
          N = mAdded.size();
          if (N > 0) {
              writer.print(prefix);
              writer.println("Added Fragments:");
              for (int i = 0; i < N; i++) {
                  Fragment f = mAdded.get(i);
                  writer.print(prefix);
                  writer.print("  #");
                  writer.print(i);
                  writer.print(": ");
                  writer.println(f.toString());
              }
          }
  
          if (mCreatedMenus != null) {
              N = mCreatedMenus.size();
              if (N > 0) {
                  writer.print(prefix); writer.println("Fragments Created Menus:");
                  for (int i=0; i<N; i++) {
                      Fragment f = mCreatedMenus.get(i);
                      writer.print(prefix); writer.print("  #"); writer.print(i);
                              writer.print(": "); writer.println(f.toString());
                  }
              }
          }
  
          if (mBackStack != null) {
              N = mBackStack.size();
              if (N > 0) {
                  writer.print(prefix); writer.println("Back Stack:");
                  for (int i=0; i<N; i++) {
                      BackStackRecord bs = mBackStack.get(i);
                      writer.print(prefix); writer.print("  #"); writer.print(i);
                              writer.print(": "); writer.println(bs.toString());
                      bs.dump(innerPrefix, fd, writer, args);
                  }
              }
          }
  
          synchronized (this) {
              if (mBackStackIndices != null) {
                  N = mBackStackIndices.size();
                  if (N > 0) {
                      writer.print(prefix); writer.println("Back Stack Indices:");
                      for (int i=0; i<N; i++) {
                          BackStackRecord bs = mBackStackIndices.get(i);
                          writer.print(prefix); writer.print("  #"); writer.print(i);
                                  writer.print(": "); writer.println(bs);
                      }
                  }
              }
  
              if (mAvailBackStackIndices != null && mAvailBackStackIndices.size() > 0) {
                  writer.print(prefix); writer.print("mAvailBackStackIndices: ");
                          writer.println(Arrays.toString(mAvailBackStackIndices.toArray()));
              }
          }
  
          if (mPendingActions != null) {
              N = mPendingActions.size();
              if (N > 0) {
                  writer.print(prefix); writer.println("Pending Actions:");
                  for (int i=0; i<N; i++) {
                      OpGenerator r = mPendingActions.get(i);
                      writer.print(prefix); writer.print("  #"); writer.print(i);
                              writer.print(": "); writer.println(r);
                  }
              }
          }
  
          writer.print(prefix); writer.println("FragmentManager misc state:");
          writer.print(prefix); writer.print("  mHost="); writer.println(mHost);
          writer.print(prefix); writer.print("  mContainer="); writer.println(mContainer);
          if (mParent != null) {
              writer.print(prefix); writer.print("  mParent="); writer.println(mParent);
          }
          writer.print(prefix); writer.print("  mCurState="); writer.print(mCurState);
                  writer.print(" mStateSaved="); writer.print(mStateSaved);
                  writer.print(" mDestroyed="); writer.println(mDestroyed);
          if (mNeedMenuInvalidate) {
              writer.print(prefix); writer.print("  mNeedMenuInvalidate=");
                      writer.println(mNeedMenuInvalidate);
          }
          if (mNoTransactionsBecause != null) {
              writer.print(prefix); writer.print("  mNoTransactionsBecause=");
                      writer.println(mNoTransactionsBecause);
          }
      }
  
      @UnsupportedAppUsage
      Animator loadAnimator(Fragment fragment, int transit, boolean enter,
              int transitionStyle) {
          Animator animObj = fragment.onCreateAnimator(transit, enter, fragment.getNextAnim());
          if (animObj != null) {
              return animObj;
          }
          
          if (fragment.getNextAnim() != 0) {
              Animator anim = AnimatorInflater.loadAnimator(mHost.getContext(),
                      fragment.getNextAnim());
              if (anim != null) {
                  return anim;
              }
          }
          
          if (transit == 0) {
              return null;
          }
          
          int styleIndex = transitToStyleIndex(transit, enter);
          if (styleIndex < 0) {
              return null;
          }
          
          if (transitionStyle == 0 && mHost.onHasWindowAnimations()) {
              transitionStyle = mHost.onGetWindowAnimations();
          }
          if (transitionStyle == 0) {
              return null;
          }
          
          TypedArray attrs = mHost.getContext().obtainStyledAttributes(transitionStyle,
                  com.android.internal.R.styleable.FragmentAnimation);
          int anim = attrs.getResourceId(styleIndex, 0);
          attrs.recycle();
          
          if (anim == 0) {
              return null;
          }
          
          return AnimatorInflater.loadAnimator(mHost.getContext(), anim);
      }
      
      public void performPendingDeferredStart(Fragment f) {
          if (f.mDeferStart) {
              if (mExecutingActions) {
                  // Wait until we're done executing our pending transactions
                  mHavePendingDeferredStart = true;
                  return;
              }
              f.mDeferStart = false;
              moveToState(f, mCurState, 0, 0, false);
          }
      }
  
      boolean isStateAtLeast(int state) {
          return mCurState >= state;
      }
  
      @SuppressWarnings("ReferenceEquality")
      void moveToState(Fragment f, int newState, int transit, int transitionStyle,
              boolean keepActive) {
          if (DEBUG && false) Log.v(TAG, "moveToState: " + f
              + " oldState=" + f.mState + " newState=" + newState
              + " mRemoving=" + f.mRemoving + " Callers=" + Debug.getCallers(5));
  
          // Fragments that are not currently added will sit in the onCreate() state.
          if ((!f.mAdded || f.mDetached) && newState > Fragment.CREATED) {
              newState = Fragment.CREATED;
          }
          if (f.mRemoving && newState > f.mState) {
              if (f.mState == Fragment.INITIALIZING && f.isInBackStack()) {
                  // Allow the fragment to be created so that it can be saved later.
                  newState = Fragment.CREATED;
              } else {
                  // While removing a fragment, we can't change it to a higher state.
                  newState = f.mState;
              }
          }
          // Defer start if requested; don't allow it to move to STARTED or higher
          // if it's not already started.
          if (f.mDeferStart && f.mState < Fragment.STARTED && newState > Fragment.STOPPED) {
              newState = Fragment.STOPPED;
          }
          if (f.mState <= newState) {
              // For fragments that are created from a layout, when restoring from
              // state we don't want to allow them to be created until they are
              // being reloaded from the layout.
              if (f.mFromLayout && !f.mInLayout) {
                  return;
              }
              if (f.getAnimatingAway() != null) {
                  // The fragment is currently being animated...  but!  Now we
                  // want to move our state back up.  Give up on waiting for the
                  // animation, move to whatever the final state should be once
                  // the animation is done, and then we can proceed from there.
                  f.setAnimatingAway(null);
                  moveToState(f, f.getStateAfterAnimating(), 0, 0, true);
              }
              switch (f.mState) {
                  case Fragment.INITIALIZING:
                      if (newState > Fragment.INITIALIZING) {
                          if (DEBUG) Log.v(TAG, "moveto CREATED: " + f);
                          if (f.mSavedFragmentState != null) {
                              f.mSavedViewState = f.mSavedFragmentState.getSparseParcelableArray(
                                      FragmentManagerImpl.VIEW_STATE_TAG);
                              f.mTarget = getFragment(f.mSavedFragmentState,
                                      FragmentManagerImpl.TARGET_STATE_TAG);
                              if (f.mTarget != null) {
                                  f.mTargetRequestCode = f.mSavedFragmentState.getInt(
                                          FragmentManagerImpl.TARGET_REQUEST_CODE_STATE_TAG, 0);
                              }
                              f.mUserVisibleHint = f.mSavedFragmentState.getBoolean(
                                      FragmentManagerImpl.USER_VISIBLE_HINT_TAG, true);
                              if (!f.mUserVisibleHint) {
                                  f.mDeferStart = true;
                                  if (newState > Fragment.STOPPED) {
                                      newState = Fragment.STOPPED;
                                  }
                              }
                          }
  
                          f.mHost = mHost;
                          f.mParentFragment = mParent;
                          f.mFragmentManager = mParent != null
                                  ? mParent.mChildFragmentManager : mHost.getFragmentManagerImpl();
  
                          // If we have a target fragment, push it along to at least CREATED
                          // so that this one can rely on it as an initialized dependency.
                          if (f.mTarget != null) {
                              if (mActive.get(f.mTarget.mIndex) != f.mTarget) {
                                  throw new IllegalStateException("Fragment " + f
                                          + " declared target fragment " + f.mTarget
                                          + " that does not belong to this FragmentManager!");
                              }
                              if (f.mTarget.mState < Fragment.CREATED) {
                                  moveToState(f.mTarget, Fragment.CREATED, 0, 0, true);
                              }
                          }
  
                          dispatchOnFragmentPreAttached(f, mHost.getContext(), false);
                          f.mCalled = false;
                          f.onAttach(mHost.getContext());
                          if (!f.mCalled) {
                              throw new SuperNotCalledException("Fragment " + f
                                      + " did not call through to super.onAttach()");
                          }
                          if (f.mParentFragment == null) {
                              mHost.onAttachFragment(f);
                          } else {
                              f.mParentFragment.onAttachFragment(f);
                          }
                          dispatchOnFragmentAttached(f, mHost.getContext(), false);
  
                          if (!f.mIsCreated) {
                              dispatchOnFragmentPreCreated(f, f.mSavedFragmentState, false);
                              f.performCreate(f.mSavedFragmentState);
                              dispatchOnFragmentCreated(f, f.mSavedFragmentState, false);
                          } else {
                              f.restoreChildFragmentState(f.mSavedFragmentState, true);
                              f.mState = Fragment.CREATED;
                          }
                          f.mRetaining = false;
                      }
                      // fall through
                  case Fragment.CREATED:
                      // This is outside the if statement below on purpose; we want this to run
                      // even if we do a moveToState from CREATED => *, CREATED => CREATED, and
                      // * => CREATED as part of the case fallthrough above.
                      ensureInflatedFragmentView(f);
  
                      if (newState > Fragment.CREATED) {
                          if (DEBUG) Log.v(TAG, "moveto ACTIVITY_CREATED: " + f);
                          if (!f.mFromLayout) {
                              ViewGroup container = null;
                              if (f.mContainerId != 0) {
                                  if (f.mContainerId == View.NO_ID) {
                                      throwException(new IllegalArgumentException(
                                              "Cannot create fragment "
                                                      + f
                                                      + " for a container view with no id"));
                                  }
                                  container = mContainer.onFindViewById(f.mContainerId);
                                  if (container == null && !f.mRestored) {
                                      String resName;
                                      try {
                                          resName = f.getResources().getResourceName(f.mContainerId);
                                      } catch (NotFoundException e) {
                                          resName = "unknown";
                                      }
                                      throwException(new IllegalArgumentException(
                                              "No view found for id 0x"
                                              + Integer.toHexString(f.mContainerId) + " ("
                                              + resName
                                              + ") for fragment " + f));
                                  }
                              }
                              f.mContainer = container;
                              f.mView = f.performCreateView(f.performGetLayoutInflater(
                                      f.mSavedFragmentState), container, f.mSavedFragmentState);
                              if (f.mView != null) {
                                  f.mView.setSaveFromParentEnabled(false);
                                  if (container != null) {
                                      container.addView(f.mView);
                                  }
                                  if (f.mHidden) {
                                      f.mView.setVisibility(View.GONE);
                                  }
                                  f.onViewCreated(f.mView, f.mSavedFragmentState);
                                  dispatchOnFragmentViewCreated(f, f.mView, f.mSavedFragmentState,
                                          false);
                                  // Only animate the view if it is visible. This is done after
                                  // dispatchOnFragmentViewCreated in case visibility is changed
                                  f.mIsNewlyAdded = (f.mView.getVisibility() == View.VISIBLE)
                                          && f.mContainer != null;
                              }
                          }
  
                          f.performActivityCreated(f.mSavedFragmentState);
                          dispatchOnFragmentActivityCreated(f, f.mSavedFragmentState, false);
                          if (f.mView != null) {
                              f.restoreViewState(f.mSavedFragmentState);
                          }
                          f.mSavedFragmentState = null;
                      }
                      // fall through
                  case Fragment.ACTIVITY_CREATED:
                      if (newState > Fragment.ACTIVITY_CREATED) {
                          f.mState = Fragment.STOPPED;
                      }
                      // fall through
                  case Fragment.STOPPED:
                      if (newState > Fragment.STOPPED) {
                          if (DEBUG) Log.v(TAG, "moveto STARTED: " + f);
                          f.performStart();
                          dispatchOnFragmentStarted(f, false);
                      }
                      // fall through
                  case Fragment.STARTED:
                      if (newState > Fragment.STARTED) {
                          if (DEBUG) Log.v(TAG, "moveto RESUMED: " + f);
                          f.performResume();
                          dispatchOnFragmentResumed(f, false);
                          // Get rid of this in case we saved it and never needed it.
                          f.mSavedFragmentState = null;
                          f.mSavedViewState = null;
                      }
              }
          } else if (f.mState > newState) {
              switch (f.mState) {
                  case Fragment.RESUMED:
                      if (newState < Fragment.RESUMED) {
                          if (DEBUG) Log.v(TAG, "movefrom RESUMED: " + f);
                          f.performPause();
                          dispatchOnFragmentPaused(f, false);
                      }
                      // fall through
                  case Fragment.STARTED:
                      if (newState < Fragment.STARTED) {
                          if (DEBUG) Log.v(TAG, "movefrom STARTED: " + f);
                          f.performStop();
                          dispatchOnFragmentStopped(f, false);
                      }
                      // fall through
                  case Fragment.STOPPED:
                  case Fragment.ACTIVITY_CREATED:
                      if (newState < Fragment.ACTIVITY_CREATED) {
                          if (DEBUG) Log.v(TAG, "movefrom ACTIVITY_CREATED: " + f);
                          if (f.mView != null) {
                              // Need to save the current view state if not
                              // done already.
                              if (mHost.onShouldSaveFragmentState(f) && f.mSavedViewState == null) {
                                  saveFragmentViewState(f);
                              }
                          }
                          f.performDestroyView();
                          dispatchOnFragmentViewDestroyed(f, false);
                          if (f.mView != null && f.mContainer != null) {
                              if (getTargetSdk() >= Build.VERSION_CODES.O) {
                                  // Stop any current animations:
                                  f.mView.clearAnimation();
                                  f.mContainer.endViewTransition(f.mView);
                              }
                              Animator anim = null;
                              if (mCurState > Fragment.INITIALIZING && !mDestroyed
                                      && f.mView.getVisibility() == View.VISIBLE
                                      && f.mView.getTransitionAlpha() > 0) {
                                  anim = loadAnimator(f, transit, false,
                                          transitionStyle);
                              }
                              f.mView.setTransitionAlpha(1f);
                              if (anim != null) {
                                  final ViewGroup container = f.mContainer;
                                  final View view = f.mView;
                                  final Fragment fragment = f;
                                  container.startViewTransition(view);
                                  f.setAnimatingAway(anim);
                                  f.setStateAfterAnimating(newState);
                                  anim.addListener(new AnimatorListenerAdapter() {
                                      @Override
                                      public void onAnimationEnd(Animator anim) {
                                          container.endViewTransition(view);
                                          Animator animator = f.getAnimatingAway();
                                          f.setAnimatingAway(null);
                                          // If the animation finished immediately, the fragment's
                                          // view will still be there. If so, we can just pretend
                                          // there was no animation and skip the moveToState()
                                          if (container.indexOfChild(view) == -1
                                                  && animator != null) {
                                              moveToState(fragment, fragment.getStateAfterAnimating(),
                                                      0, 0, false);
                                          }
                                      }
                                  });
                                  anim.setTarget(f.mView);
                                  setHWLayerAnimListenerIfAlpha(f.mView, anim);
                                  anim.start();
  
                              }
                              f.mContainer.removeView(f.mView);
                          }
                          f.mContainer = null;
                          f.mView = null;
                          f.mInLayout = false;
                      }
                      // fall through
                  case Fragment.CREATED:
                      if (newState < Fragment.CREATED) {
                          if (mDestroyed) {
                              if (f.getAnimatingAway() != null) {
                                  // The fragment's containing activity is
                                  // being destroyed, but this fragment is
                                  // currently animating away.  Stop the
                                  // animation right now -- it is not needed,
                                  // and we can't wait any more on destroying
                                  // the fragment.
                                  Animator anim = f.getAnimatingAway();
                                  f.setAnimatingAway(null);
                                  anim.cancel();
                              }
                          }
                          if (f.getAnimatingAway() != null) {
                              // We are waiting for the fragment's view to finish
                              // animating away.  Just make a note of the state
                              // the fragment now should move to once the animation
                              // is done.
                              f.setStateAfterAnimating(newState);
                              newState = Fragment.CREATED;
                          } else {
                              if (DEBUG) Log.v(TAG, "movefrom CREATED: " + f);
                              if (!f.mRetaining) {
                                  f.performDestroy();
                                  dispatchOnFragmentDestroyed(f, false);
                              } else {
                                  f.mState = Fragment.INITIALIZING;
                              }
  
                              f.performDetach();
                              dispatchOnFragmentDetached(f, false);
                              if (!keepActive) {
                                  if (!f.mRetaining) {
                                      makeInactive(f);
                                  } else {
                                      f.mHost = null;
                                      f.mParentFragment = null;
                                      f.mFragmentManager = null;
                                  }
                              }
                          }
                      }
              }
          }
          
          if (f.mState != newState) {
              Log.w(TAG, "moveToState: Fragment state for " + f + " not updated inline; "
                      + "expected state " + newState + " found " + f.mState);
              f.mState = newState;
          }
      }
      
      void moveToState(Fragment f) {
          moveToState(f, mCurState, 0, 0, false);
      }
  
      void ensureInflatedFragmentView(Fragment f) {
          if (f.mFromLayout && !f.mPerformedCreateView) {
              f.mView = f.performCreateView(f.performGetLayoutInflater(
                      f.mSavedFragmentState), null, f.mSavedFragmentState);
              if (f.mView != null) {
                  f.mView.setSaveFromParentEnabled(false);
                  if (f.mHidden) f.mView.setVisibility(View.GONE);
                  f.onViewCreated(f.mView, f.mSavedFragmentState);
                  dispatchOnFragmentViewCreated(f, f.mView, f.mSavedFragmentState, false);
              }
          }
      }
  
      /**
       * Fragments that have been shown or hidden don't have their visibility changed or
       * animations run during the {@link #showFragment(Fragment)} or {@link #hideFragment(Fragment)}
       * calls. After fragments are brought to their final state in
       * {@link #moveFragmentToExpectedState(Fragment)} the fragments that have been shown or
       * hidden must have their visibility changed and their animations started here.
       *
       * @param fragment The fragment with mHiddenChanged = true that should change its View's
       *                 visibility and start the show or hide animation.
       */
      void completeShowHideFragment(final Fragment fragment) {
          if (fragment.mView != null) {
              Animator anim = loadAnimator(fragment, fragment.getNextTransition(), !fragment.mHidden,
                      fragment.getNextTransitionStyle());
              if (anim != null) {
                  anim.setTarget(fragment.mView);
                  if (fragment.mHidden) {
                      if (fragment.isHideReplaced()) {
                          fragment.setHideReplaced(false);
                      } else {
                          final ViewGroup container = fragment.mContainer;
                          final View animatingView = fragment.mView;
                          if (container != null) {
                              container.startViewTransition(animatingView);
                          }
                          // Delay the actual hide operation until the animation finishes, otherwise
                          // the fragment will just immediately disappear
                          anim.addListener(new AnimatorListenerAdapter() {
                              @Override
                              public void onAnimationEnd(Animator animation) {
                                  if (container != null) {
                                      container.endViewTransition(animatingView);
                                  }
                                  animation.removeListener(this);
                                  animatingView.setVisibility(View.GONE);
                              }
                          });
                      }
                  } else {
                      fragment.mView.setVisibility(View.VISIBLE);
                  }
                  setHWLayerAnimListenerIfAlpha(fragment.mView, anim);
                  anim.start();
              } else {
                  final int visibility = fragment.mHidden && !fragment.isHideReplaced()
                          ? View.GONE
                          : View.VISIBLE;
                  fragment.mView.setVisibility(visibility);
                  if (fragment.isHideReplaced()) {
                      fragment.setHideReplaced(false);
                  }
              }
          }
          if (fragment.mAdded && fragment.mHasMenu && fragment.mMenuVisible) {
              mNeedMenuInvalidate = true;
          }
          fragment.mHiddenChanged = false;
          fragment.onHiddenChanged(fragment.mHidden);
      }
  
      /**
       * Moves a fragment to its expected final state or the fragment manager's state, depending
       * on whether the fragment manager's state is raised properly.
       *
       * @param f The fragment to change.
       */
      void moveFragmentToExpectedState(final Fragment f) {
          if (f == null) {
              return;
          }
          int nextState = mCurState;
          if (f.mRemoving) {
              if (f.isInBackStack()) {
                  nextState = Math.min(nextState, Fragment.CREATED);
              } else {
                  nextState = Math.min(nextState, Fragment.INITIALIZING);
              }
          }
  
          moveToState(f, nextState, f.getNextTransition(), f.getNextTransitionStyle(), false);
  
          if (f.mView != null) {
              // Move the view if it is out of order
              Fragment underFragment = findFragmentUnder(f);
              if (underFragment != null) {
                  final View underView = underFragment.mView;
                  // make sure this fragment is in the right order.
                  final ViewGroup container = f.mContainer;
                  int underIndex = container.indexOfChild(underView);
                  int viewIndex = container.indexOfChild(f.mView);
                  if (viewIndex < underIndex) {
                      container.removeViewAt(viewIndex);
                      container.addView(f.mView, underIndex);
                  }
              }
              if (f.mIsNewlyAdded && f.mContainer != null) {
                  // Make it visible and run the animations
                  f.mView.setTransitionAlpha(1f);
                  f.mIsNewlyAdded = false;
                  // run animations:
                  Animator anim = loadAnimator(f, f.getNextTransition(), true, f.getNextTransitionStyle());
                  if (anim != null) {
                      anim.setTarget(f.mView);
                      setHWLayerAnimListenerIfAlpha(f.mView, anim);
                      anim.start();
                  }
              }
          }
          if (f.mHiddenChanged) {
              completeShowHideFragment(f);
          }
      }
  
      /**
       * Changes the state of the fragment manager to {@code newState}. If the fragment manager
       * changes state or {@code always} is {@code true}, any fragments within it have their
       * states updated as well.
       *
       * @param newState The new state for the fragment manager
       * @param always If {@code true}, all fragments update their state, even
       *               if {@code newState} matches the current fragment manager's state.
       */
      void moveToState(int newState, boolean always) {
          if (mHost == null && newState != Fragment.INITIALIZING) {
              throw new IllegalStateException("No activity");
          }
  
          if (!always && mCurState == newState) {
              return;
          }
  
          mCurState = newState;
  
          if (mActive != null) {
              boolean loadersRunning = false;
  
              // Must add them in the proper order. mActive fragments may be out of order
              final int numAdded = mAdded.size();
              for (int i = 0; i < numAdded; i++) {
                  Fragment f = mAdded.get(i);
                  moveFragmentToExpectedState(f);
                  if (f.mLoaderManager != null) {
                      loadersRunning |= f.mLoaderManager.hasRunningLoaders();
                  }
              }
  
              // Now iterate through all active fragments. These will include those that are removed
              // and detached.
              final int numActive = mActive.size();
              for (int i = 0; i < numActive; i++) {
                  Fragment f = mActive.valueAt(i);
                  if (f != null && (f.mRemoving || f.mDetached) && !f.mIsNewlyAdded) {
                      moveFragmentToExpectedState(f);
                      if (f.mLoaderManager != null) {
                          loadersRunning |= f.mLoaderManager.hasRunningLoaders();
                      }
                  }
              }
  
              if (!loadersRunning) {
                  startPendingDeferredFragments();
              }
  
              if (mNeedMenuInvalidate && mHost != null && mCurState == Fragment.RESUMED) {
                  mHost.onInvalidateOptionsMenu();
                  mNeedMenuInvalidate = false;
              }
          }
      }
  
      void startPendingDeferredFragments() {
          if (mActive == null) return;
  
          for (int i=0; i<mActive.size(); i++) {
              Fragment f = mActive.valueAt(i);
              if (f != null) {
                  performPendingDeferredStart(f);
              }
          }
      }
  
      void makeActive(Fragment f) {
          if (f.mIndex >= 0) {
              return;
          }
  
          f.setIndex(mNextFragmentIndex++, mParent);
          if (mActive == null) {
              mActive = new SparseArray<>();
          }
          mActive.put(f.mIndex, f);
          if (DEBUG) Log.v(TAG, "Allocated fragment index " + f);
      }
      
      void makeInactive(Fragment f) {
          if (f.mIndex < 0) {
              return;
          }
          
          if (DEBUG) Log.v(TAG, "Freeing fragment index " + f);
          // Don't remove yet. That happens in burpActive(). This prevents
          // concurrent modification while iterating over mActive
          mActive.put(f.mIndex, null);
          mHost.inactivateFragment(f.mWho);
          f.initState();
      }
      
      public void addFragment(Fragment fragment, boolean moveToStateNow) {
          if (DEBUG) Log.v(TAG, "add: " + fragment);
          makeActive(fragment);
          if (!fragment.mDetached) {
              if (mAdded.contains(fragment)) {
                  throw new IllegalStateException("Fragment already added: " + fragment);
              }
              synchronized (mAdded) {
                  mAdded.add(fragment);
              }
              fragment.mAdded = true;
              fragment.mRemoving = false;
              if (fragment.mView == null) {
                  fragment.mHiddenChanged = false;
              }
              if (fragment.mHasMenu && fragment.mMenuVisible) {
                  mNeedMenuInvalidate = true;
              }
              if (moveToStateNow) {
                  moveToState(fragment);
              }
          }
      }
  
      public void removeFragment(Fragment fragment) {
          if (DEBUG) Log.v(TAG, "remove: " + fragment + " nesting=" + fragment.mBackStackNesting);
          final boolean inactive = !fragment.isInBackStack();
          if (!fragment.mDetached || inactive) {
              if (false) {
                  // Would be nice to catch a bad remove here, but we need
                  // time to test this to make sure we aren't crashes cases
                  // where it is not a problem.
                  if (!mAdded.contains(fragment)) {
                      throw new IllegalStateException("Fragment not added: " + fragment);
                  }
              }
              synchronized (mAdded) {
                  mAdded.remove(fragment);
              }
              if (fragment.mHasMenu && fragment.mMenuVisible) {
                  mNeedMenuInvalidate = true;
              }
              fragment.mAdded = false;
              fragment.mRemoving = true;
          }
      }
  
      /**
       * Marks a fragment as hidden to be later animated in with
       * {@link #completeShowHideFragment(Fragment)}.
       *
       * @param fragment The fragment to be shown.
       */
      public void hideFragment(Fragment fragment) {
          if (DEBUG) Log.v(TAG, "hide: " + fragment);
          if (!fragment.mHidden) {
              fragment.mHidden = true;
              // Toggle hidden changed so that if a fragment goes through show/hide/show
              // it doesn't go through the animation.
              fragment.mHiddenChanged = !fragment.mHiddenChanged;
          }
      }
  
      /**
       * Marks a fragment as shown to be later animated in with
       * {@link #completeShowHideFragment(Fragment)}.
       *
       * @param fragment The fragment to be shown.
       */
      public void showFragment(Fragment fragment) {
          if (DEBUG) Log.v(TAG, "show: " + fragment);
          if (fragment.mHidden) {
              fragment.mHidden = false;
              // Toggle hidden changed so that if a fragment goes through show/hide/show
              // it doesn't go through the animation.
              fragment.mHiddenChanged = !fragment.mHiddenChanged;
          }
      }
  
      public void detachFragment(Fragment fragment) {
          if (DEBUG) Log.v(TAG, "detach: " + fragment);
          if (!fragment.mDetached) {
              fragment.mDetached = true;
              if (fragment.mAdded) {
                  // We are not already in back stack, so need to remove the fragment.
                  if (DEBUG) Log.v(TAG, "remove from detach: " + fragment);
                  synchronized (mAdded) {
                      mAdded.remove(fragment);
                  }
                  if (fragment.mHasMenu && fragment.mMenuVisible) {
                      mNeedMenuInvalidate = true;
                  }
                  fragment.mAdded = false;
              }
          }
      }
  
      public void attachFragment(Fragment fragment) {
          if (DEBUG) Log.v(TAG, "attach: " + fragment);
          if (fragment.mDetached) {
              fragment.mDetached = false;
              if (!fragment.mAdded) {
                  if (mAdded.contains(fragment)) {
                      throw new IllegalStateException("Fragment already added: " + fragment);
                  }
                  if (DEBUG) Log.v(TAG, "add from attach: " + fragment);
                  synchronized (mAdded) {
                      mAdded.add(fragment);
                  }
                  fragment.mAdded = true;
                  if (fragment.mHasMenu && fragment.mMenuVisible) {
                      mNeedMenuInvalidate = true;
                  }
              }
          }
      }
  
      public Fragment findFragmentById(int id) {
          // First look through added fragments.
          for (int i = mAdded.size() - 1; i >= 0; i--) {
              Fragment f = mAdded.get(i);
              if (f != null && f.mFragmentId == id) {
                  return f;
              }
          }
          if (mActive != null) {
              // Now for any known fragment.
              for (int i=mActive.size()-1; i>=0; i--) {
                  Fragment f = mActive.valueAt(i);
                  if (f != null && f.mFragmentId == id) {
                      return f;
                  }
              }
          }
          return null;
      }
      
      public Fragment findFragmentByTag(String tag) {
          if (tag != null) {
              // First look through added fragments.
              for (int i=mAdded.size()-1; i>=0; i--) {
                  Fragment f = mAdded.get(i);
                  if (f != null && tag.equals(f.mTag)) {
                      return f;
                  }
              }
          }
          if (mActive != null && tag != null) {
              // Now for any known fragment.
              for (int i=mActive.size()-1; i>=0; i--) {
                  Fragment f = mActive.valueAt(i);
                  if (f != null && tag.equals(f.mTag)) {
                      return f;
                  }
              }
          }
          return null;
      }
  
      public Fragment findFragmentByWho(String who) {
          if (mActive != null && who != null) {
              for (int i=mActive.size()-1; i>=0; i--) {
                  Fragment f = mActive.valueAt(i);
                  if (f != null && (f=f.findFragmentByWho(who)) != null) {
                      return f;
                  }
              }
          }
          return null;
      }
      
      private void checkStateLoss() {
          if (mStateSaved) {
              throw new IllegalStateException(
                      "Can not perform this action after onSaveInstanceState");
          }
          if (mNoTransactionsBecause != null) {
              throw new IllegalStateException(
                      "Can not perform this action inside of " + mNoTransactionsBecause);
          }
      }
  
      @Override
      public boolean isStateSaved() {
          return mStateSaved;
      }
  
      /**
       * Adds an action to the queue of pending actions.
       *
       * @param action the action to add
       * @param allowStateLoss whether to allow loss of state information
       * @throws IllegalStateException if the activity has been destroyed
       */
      public void enqueueAction(OpGenerator action, boolean allowStateLoss) {
          if (!allowStateLoss) {
              checkStateLoss();
          }
          synchronized (this) {
              if (mDestroyed || mHost == null) {
                  if (allowStateLoss) {
                      // This FragmentManager isn't attached, so drop the entire transaction.
                      return;
                  }
                  throw new IllegalStateException("Activity has been destroyed");
              }
              if (mPendingActions == null) {
                  mPendingActions = new ArrayList<>();
              }
              mPendingActions.add(action);
              scheduleCommit();
          }
      }
  
      /**
       * Schedules the execution when one hasn't been scheduled already. This should happen
       * the first time {@link #enqueueAction(OpGenerator, boolean)} is called or when
       * a postponed transaction has been started with
       * {@link Fragment#startPostponedEnterTransition()}
       */
      private void scheduleCommit() {
          synchronized (this) {
              boolean postponeReady =
                      mPostponedTransactions != null && !mPostponedTransactions.isEmpty();
              boolean pendingReady = mPendingActions != null && mPendingActions.size() == 1;
              if (postponeReady || pendingReady) {
                  mHost.getHandler().removeCallbacks(mExecCommit);
                  mHost.getHandler().post(mExecCommit);
              }
          }
      }
      
      public int allocBackStackIndex(BackStackRecord bse) {
          synchronized (this) {
              if (mAvailBackStackIndices == null || mAvailBackStackIndices.size() <= 0) {
                  if (mBackStackIndices == null) {
                      mBackStackIndices = new ArrayList<BackStackRecord>();
                  }
                  int index = mBackStackIndices.size();
                  if (DEBUG) Log.v(TAG, "Setting back stack index " + index + " to " + bse);
                  mBackStackIndices.add(bse);
                  return index;
  
              } else {
                  int index = mAvailBackStackIndices.remove(mAvailBackStackIndices.size()-1);
                  if (DEBUG) Log.v(TAG, "Adding back stack index " + index + " with " + bse);
                  mBackStackIndices.set(index, bse);
                  return index;
              }
          }
      }
  
      public void setBackStackIndex(int index, BackStackRecord bse) {
          synchronized (this) {
              if (mBackStackIndices == null) {
                  mBackStackIndices = new ArrayList<BackStackRecord>();
              }
              int N = mBackStackIndices.size();
              if (index < N) {
                  if (DEBUG) Log.v(TAG, "Setting back stack index " + index + " to " + bse);
                  mBackStackIndices.set(index, bse);
              } else {
                  while (N < index) {
                      mBackStackIndices.add(null);
                      if (mAvailBackStackIndices == null) {
                          mAvailBackStackIndices = new ArrayList<Integer>();
                      }
                      if (DEBUG) Log.v(TAG, "Adding available back stack index " + N);
                      mAvailBackStackIndices.add(N);
                      N++;
                  }
                  if (DEBUG) Log.v(TAG, "Adding back stack index " + index + " with " + bse);
                  mBackStackIndices.add(bse);
              }
          }
      }
  
      public void freeBackStackIndex(int index) {
          synchronized (this) {
              mBackStackIndices.set(index, null);
              if (mAvailBackStackIndices == null) {
                  mAvailBackStackIndices = new ArrayList<Integer>();
              }
              if (DEBUG) Log.v(TAG, "Freeing back stack index " + index);
              mAvailBackStackIndices.add(index);
          }
      }
  
      /**
       * Broken out from exec*, this prepares for gathering and executing operations.
       *
       * @param allowStateLoss true if state loss should be ignored or false if it should be
       *                       checked.
       */
      private void ensureExecReady(boolean allowStateLoss) {
          if (mExecutingActions) {
              throw new IllegalStateException("FragmentManager is already executing transactions");
          }
  
          if (Looper.myLooper() != mHost.getHandler().getLooper()) {
              throw new IllegalStateException("Must be called from main thread of fragment host");
          }
  
          if (!allowStateLoss) {
              checkStateLoss();
          }
  
          if (mTmpRecords == null) {
              mTmpRecords = new ArrayList<>();
              mTmpIsPop = new ArrayList<>();
          }
          mExecutingActions = true;
          try {
              executePostponedTransaction(null, null);
          } finally {
              mExecutingActions = false;
          }
      }
  
      public void execSingleAction(OpGenerator action, boolean allowStateLoss) {
          if (allowStateLoss && (mHost == null || mDestroyed)) {
              // This FragmentManager isn't attached, so drop the entire transaction.
              return;
          }
          ensureExecReady(allowStateLoss);
          if (action.generateOps(mTmpRecords, mTmpIsPop)) {
              mExecutingActions = true;
              try {
                  removeRedundantOperationsAndExecute(mTmpRecords, mTmpIsPop);
              } finally {
                  cleanupExec();
              }
          }
  
          doPendingDeferredStart();
          burpActive();
      }
  
      /**
       * Broken out of exec*, this cleans up the mExecutingActions and the temporary structures
       * used in executing operations.
       */
      private void cleanupExec() {
          mExecutingActions = false;
          mTmpIsPop.clear();
          mTmpRecords.clear();
      }
  
      /**
       * Only call from main thread!
       */
      public boolean execPendingActions() {
          ensureExecReady(true);
  
          boolean didSomething = false;
          while (generateOpsForPendingActions(mTmpRecords, mTmpIsPop)) {
              mExecutingActions = true;
              try {
                  removeRedundantOperationsAndExecute(mTmpRecords, mTmpIsPop);
              } finally {
                  cleanupExec();
              }
              didSomething = true;
          }
  
          doPendingDeferredStart();
          burpActive();
  
          return didSomething;
      }
  
      /**
       * Complete the execution of transactions that have previously been postponed, but are
       * now ready.
       */
      private void executePostponedTransaction(ArrayList<BackStackRecord> records,
              ArrayList<Boolean> isRecordPop) {
          int numPostponed = mPostponedTransactions == null ? 0 : mPostponedTransactions.size();
          for (int i = 0; i < numPostponed; i++) {
              StartEnterTransitionListener listener = mPostponedTransactions.get(i);
              if (records != null && !listener.mIsBack) {
                  int index = records.indexOf(listener.mRecord);
                  if (index != -1 && isRecordPop.get(index)) {
                      listener.cancelTransaction();
                      continue;
                  }
              }
              if (listener.isReady() || (records != null &&
                      listener.mRecord.interactsWith(records, 0, records.size()))) {
                  mPostponedTransactions.remove(i);
                  i--;
                  numPostponed--;
                  int index;
                  if (records != null && !listener.mIsBack &&
                          (index = records.indexOf(listener.mRecord)) != -1 &&
                          isRecordPop.get(index)) {
                      // This is popping a postponed transaction
                      listener.cancelTransaction();
                  } else {
                      listener.completeTransaction();
                  }
              }
          }
      }
  
      /**
       * Remove redundant BackStackRecord operations and executes them. This method merges operations
       * of proximate records that allow reordering. See
       * {@link FragmentTransaction#setReorderingAllowed(boolean)}.
       * <p>
       * For example, a transaction that adds to the back stack and then another that pops that
       * back stack record will be optimized to remove the unnecessary operation.
       * <p>
       * Likewise, two transactions committed that are executed at the same time will be optimized
       * to remove the redundant operations as well as two pop operations executed together.
       *
       * @param records The records pending execution
       * @param isRecordPop The direction that these records are being run.
       */
      private void removeRedundantOperationsAndExecute(ArrayList<BackStackRecord> records,
              ArrayList<Boolean> isRecordPop) {
          if (records == null || records.isEmpty()) {
              return;
          }
  
          if (isRecordPop == null || records.size() != isRecordPop.size()) {
              throw new IllegalStateException("Internal error with the back stack records");
          }
  
          // Force start of any postponed transactions that interact with scheduled transactions:
          executePostponedTransaction(records, isRecordPop);
  
          final int numRecords = records.size();
          int startIndex = 0;
          for (int recordNum = 0; recordNum < numRecords; recordNum++) {
              final boolean canReorder = records.get(recordNum).mReorderingAllowed;
              if (!canReorder) {
                  // execute all previous transactions
                  if (startIndex != recordNum) {
                      executeOpsTogether(records, isRecordPop, startIndex, recordNum);
                  }
                  // execute all pop operations that don't allow reordering together or
                  // one add operation
                  int reorderingEnd = recordNum + 1;
                  if (isRecordPop.get(recordNum)) {
                      while (reorderingEnd < numRecords
                              && isRecordPop.get(reorderingEnd)
                              && !records.get(reorderingEnd).mReorderingAllowed) {
                          reorderingEnd++;
                      }
                  }
                  executeOpsTogether(records, isRecordPop, recordNum, reorderingEnd);
                  startIndex = reorderingEnd;
                  recordNum = reorderingEnd - 1;
              }
          }
          if (startIndex != numRecords) {
              executeOpsTogether(records, isRecordPop, startIndex, numRecords);
          }
      }
  
      /**
       * Executes a subset of a list of BackStackRecords, all of which either allow reordering or
       * do not allow ordering.
       * @param records A list of BackStackRecords that are to be executed together
       * @param isRecordPop The direction that these records are being run.
       * @param startIndex The index of the first record in <code>records</code> to be executed
       * @param endIndex One more than the final record index in <code>records</code> to executed.
       */
      private void executeOpsTogether(ArrayList<BackStackRecord> records,
              ArrayList<Boolean> isRecordPop, int startIndex, int endIndex) {
          final boolean allowReordering = records.get(startIndex).mReorderingAllowed;
          boolean addToBackStack = false;
          if (mTmpAddedFragments == null) {
              mTmpAddedFragments = new ArrayList<>();
          } else {
              mTmpAddedFragments.clear();
          }
          mTmpAddedFragments.addAll(mAdded);
          Fragment oldPrimaryNav = getPrimaryNavigationFragment();
          for (int recordNum = startIndex; recordNum < endIndex; recordNum++) {
              final BackStackRecord record = records.get(recordNum);
              final boolean isPop = isRecordPop.get(recordNum);
              if (!isPop) {
                  oldPrimaryNav = record.expandOps(mTmpAddedFragments, oldPrimaryNav);
              } else {
                  record.trackAddedFragmentsInPop(mTmpAddedFragments);
              }
              addToBackStack = addToBackStack || record.mAddToBackStack;
          }
          mTmpAddedFragments.clear();
  
          if (!allowReordering) {
              FragmentTransition.startTransitions(this, records, isRecordPop, startIndex, endIndex,
                      false);
          }
          executeOps(records, isRecordPop, startIndex, endIndex);
  
          int postponeIndex = endIndex;
          if (allowReordering) {
              ArraySet<Fragment> addedFragments = new ArraySet<>();
              addAddedFragments(addedFragments);
              postponeIndex = postponePostponableTransactions(records, isRecordPop,
                      startIndex, endIndex, addedFragments);
              makeRemovedFragmentsInvisible(addedFragments);
          }
  
          if (postponeIndex != startIndex && allowReordering) {
              // need to run something now
              FragmentTransition.startTransitions(this, records, isRecordPop, startIndex,
                      postponeIndex, true);
              moveToState(mCurState, true);
          }
  
          for (int recordNum = startIndex; recordNum < endIndex; recordNum++) {
              final BackStackRecord record = records.get(recordNum);
              final boolean isPop = isRecordPop.get(recordNum);
              if (isPop && record.mIndex >= 0) {
                  freeBackStackIndex(record.mIndex);
                  record.mIndex = -1;
              }
              record.runOnCommitRunnables();
          }
  
          if (addToBackStack) {
              reportBackStackChanged();
          }
      }
  
      /**
       * Any fragments that were removed because they have been postponed should have their views
       * made invisible by setting their transition alpha to 0.
       *
       * @param fragments The fragments that were added during operation execution. Only the ones
       *                  that are no longer added will have their transition alpha changed.
       */
      private void makeRemovedFragmentsInvisible(ArraySet<Fragment> fragments) {
          final int numAdded = fragments.size();
          for (int i = 0; i < numAdded; i++) {
              final Fragment fragment = fragments.valueAt(i);
              if (!fragment.mAdded) {
                  final View view = fragment.getView();
                  view.setTransitionAlpha(0f);
              }
          }
      }
  
      /**
       * Examine all transactions and determine which ones are marked as postponed. Those will
       * have their operations rolled back and moved to the end of the record list (up to endIndex).
       * It will also add the postponed transaction to the queue.
       *
       * @param records A list of BackStackRecords that should be checked.
       * @param isRecordPop The direction that these records are being run.
       * @param startIndex The index of the first record in <code>records</code> to be checked
       * @param endIndex One more than the final record index in <code>records</code> to be checked.
       * @return The index of the first postponed transaction or endIndex if no transaction was
       * postponed.
       */
      private int postponePostponableTransactions(ArrayList<BackStackRecord> records,
              ArrayList<Boolean> isRecordPop, int startIndex, int endIndex,
              ArraySet<Fragment> added) {
          int postponeIndex = endIndex;
          for (int i = endIndex - 1; i >= startIndex; i--) {
              final BackStackRecord record = records.get(i);
              final boolean isPop = isRecordPop.get(i);
              boolean isPostponed = record.isPostponed() &&
                      !record.interactsWith(records, i + 1, endIndex);
              if (isPostponed) {
                  if (mPostponedTransactions == null) {
                      mPostponedTransactions = new ArrayList<>();
                  }
                  StartEnterTransitionListener listener =
                          new StartEnterTransitionListener(record, isPop);
                  mPostponedTransactions.add(listener);
                  record.setOnStartPostponedListener(listener);
  
                  // roll back the transaction
                  if (isPop) {
                      record.executeOps();
                  } else {
                      record.executePopOps(false);
                  }
  
                  // move to the end
                  postponeIndex--;
                  if (i != postponeIndex) {
                      records.remove(i);
                      records.add(postponeIndex, record);
                  }
  
                  // different views may be visible now
                  addAddedFragments(added);
              }
          }
          return postponeIndex;
      }
  
      /**
       * When a postponed transaction is ready to be started, this completes the transaction,
       * removing, hiding, or showing views as well as starting the animations and transitions.
       * <p>
       * {@code runtransitions} is set to false when the transaction postponement was interrupted
       * abnormally -- normally by a new transaction being started that affects the postponed
       * transaction.
       *
       * @param record The transaction to run
       * @param isPop true if record is popping or false if it is adding
       * @param runTransitions true if the fragment transition should be run or false otherwise.
       * @param moveToState true if the state should be changed after executing the operations.
       *                    This is false when the transaction is canceled when a postponed
       *                    transaction is popped.
       */
      private void completeExecute(BackStackRecord record, boolean isPop, boolean runTransitions,
              boolean moveToState) {
          if (isPop) {
              record.executePopOps(moveToState);
          } else {
              record.executeOps();
          }
          ArrayList<BackStackRecord> records = new ArrayList<>(1);
          ArrayList<Boolean> isRecordPop = new ArrayList<>(1);
          records.add(record);
          isRecordPop.add(isPop);
          if (runTransitions) {
              FragmentTransition.startTransitions(this, records, isRecordPop, 0, 1, true);
          }
          if (moveToState) {
              moveToState(mCurState, true);
          }
  
          if (mActive != null) {
              final int numActive = mActive.size();
              for (int i = 0; i < numActive; i++) {
                  // Allow added fragments to be removed during the pop since we aren't going
                  // to move them to the final state with moveToState(mCurState).
                  Fragment fragment = mActive.valueAt(i);
                  if (fragment != null && fragment.mView != null && fragment.mIsNewlyAdded
                          && record.interactsWith(fragment.mContainerId)) {
                      fragment.mIsNewlyAdded = false;
                  }
              }
          }
      }
  
      /**
       * Find a fragment within the fragment's container whose View should be below the passed
       * fragment. {@code null} is returned when the fragment has no View or if there should be
       * no fragment with a View below the given fragment.
       *
       * As an example, if mAdded has two Fragments with Views sharing the same container:
       * FragmentA
       * FragmentB
       *
       * Then, when processing FragmentB, FragmentA will be returned. If, however, FragmentA
       * had no View, null would be returned.
       *
       * @param f The fragment that may be on top of another fragment.
       * @return The fragment with a View under f, if one exists or null if f has no View or
       * there are no fragments with Views in the same container.
       */
      private Fragment findFragmentUnder(Fragment f) {
          final ViewGroup container = f.mContainer;
          final View view = f.mView;
  
          if (container == null || view == null) {
              return null;
          }
  
          final int fragmentIndex = mAdded.indexOf(f);
          for (int i = fragmentIndex - 1; i >= 0; i--) {
              Fragment underFragment = mAdded.get(i);
              if (underFragment.mContainer == container && underFragment.mView != null) {
                  // Found the fragment under this one
                  return underFragment;
              }
          }
          return null;
      }
  
      /**
       * Run the operations in the BackStackRecords, either to push or pop.
       *
       * @param records The list of records whose operations should be run.
       * @param isRecordPop The direction that these records are being run.
       * @param startIndex The index of the first entry in records to run.
       * @param endIndex One past the index of the final entry in records to run.
       */
      private static void executeOps(ArrayList<BackStackRecord> records,
              ArrayList<Boolean> isRecordPop, int startIndex, int endIndex) {
          for (int i = startIndex; i < endIndex; i++) {
              final BackStackRecord record = records.get(i);
              final boolean isPop = isRecordPop.get(i);
              if (isPop) {
                  record.bumpBackStackNesting(-1);
                  // Only execute the add operations at the end of
                  // all transactions.
                  boolean moveToState = i == (endIndex - 1);
                  record.executePopOps(moveToState);
              } else {
                  record.bumpBackStackNesting(1);
                  record.executeOps();
              }
          }
      }
  
      /**
       * Ensure that fragments that are added are moved to at least the CREATED state.
       * Any newly-added Views are inserted into {@code added} so that the Transaction can be
       * postponed with {@link Fragment#postponeEnterTransition()}. They will later be made
       * invisible by changing their transitionAlpha to 0 if they have been removed when postponed.
       */
      private void addAddedFragments(ArraySet<Fragment> added) {
          if (mCurState < Fragment.CREATED) {
              return;
          }
          // We want to leave the fragment in the started state
          final int state = Math.min(mCurState, Fragment.STARTED);
          final int numAdded = mAdded.size();
          for (int i = 0; i < numAdded; i++) {
              Fragment fragment = mAdded.get(i);
              if (fragment.mState < state) {
                  moveToState(fragment, state, fragment.getNextAnim(), fragment.getNextTransition(), false);
                  if (fragment.mView != null && !fragment.mHidden && fragment.mIsNewlyAdded) {
                      added.add(fragment);
                  }
              }
          }
      }
  
      /**
       * Starts all postponed transactions regardless of whether they are ready or not.
       */
      private void forcePostponedTransactions() {
          if (mPostponedTransactions != null) {
              while (!mPostponedTransactions.isEmpty()) {
                  mPostponedTransactions.remove(0).completeTransaction();
              }
          }
      }
  
      /**
       * Ends the animations of fragments so that they immediately reach the end state.
       * This is used prior to saving the state so that the correct state is saved.
       */
      private void endAnimatingAwayFragments() {
          final int numFragments = mActive == null ? 0 : mActive.size();
          for (int i = 0; i < numFragments; i++) {
              Fragment fragment = mActive.valueAt(i);
              if (fragment != null && fragment.getAnimatingAway() != null) {
                  // Give up waiting for the animation and just end it.
                  fragment.getAnimatingAway().end();
              }
          }
      }
  
      /**
       * Adds all records in the pending actions to records and whether they are add or pop
       * operations to isPop. After executing, the pending actions will be empty.
       *
       * @param records All pending actions will generate BackStackRecords added to this.
       *                This contains the transactions, in order, to execute.
       * @param isPop All pending actions will generate booleans to add to this. This contains
       *              an entry for each entry in records to indicate whether or not it is a
       *              pop action.
       */
      private boolean generateOpsForPendingActions(ArrayList<BackStackRecord> records,
              ArrayList<Boolean> isPop) {
          boolean didSomething = false;
          synchronized (this) {
              if (mPendingActions == null || mPendingActions.size() == 0) {
                  return false;
              }
  
              final int numActions = mPendingActions.size();
              for (int i = 0; i < numActions; i++) {
                  didSomething |= mPendingActions.get(i).generateOps(records, isPop);
              }
              mPendingActions.clear();
              mHost.getHandler().removeCallbacks(mExecCommit);
          }
          return didSomething;
      }
  
      void doPendingDeferredStart() {
          if (mHavePendingDeferredStart) {
              boolean loadersRunning = false;
              for (int i=0; i<mActive.size(); i++) {
                  Fragment f = mActive.valueAt(i);
                  if (f != null && f.mLoaderManager != null) {
                      loadersRunning |= f.mLoaderManager.hasRunningLoaders();
                  }
              }
              if (!loadersRunning) {
                  mHavePendingDeferredStart = false;
                  startPendingDeferredFragments();
              }
          }
      }
  
      void reportBackStackChanged() {
          if (mBackStackChangeListeners != null) {
              for (int i=0; i<mBackStackChangeListeners.size(); i++) {
                  mBackStackChangeListeners.get(i).onBackStackChanged();
              }
          }
      }
  
      void addBackStackState(BackStackRecord state) {
          if (mBackStack == null) {
              mBackStack = new ArrayList<BackStackRecord>();
          }
          mBackStack.add(state);
      }
  
      boolean popBackStackState(ArrayList<BackStackRecord> records, ArrayList<Boolean> isRecordPop,
              String name, int id, int flags) {
          if (mBackStack == null) {
              return false;
          }
          if (name == null && id < 0 && (flags & POP_BACK_STACK_INCLUSIVE) == 0) {
              int last = mBackStack.size() - 1;
              if (last < 0) {
                  return false;
              }
              records.add(mBackStack.remove(last));
              isRecordPop.add(true);
          } else {
              int index = -1;
              if (name != null || id >= 0) {
                  // If a name or ID is specified, look for that place in
                  // the stack.
                  index = mBackStack.size()-1;
                  while (index >= 0) {
                      BackStackRecord bss = mBackStack.get(index);
                      if (name != null && name.equals(bss.getName())) {
                          break;
                      }
                      if (id >= 0 && id == bss.mIndex) {
                          break;
                      }
                      index--;
                  }
                  if (index < 0) {
                      return false;
                  }
                  if ((flags&POP_BACK_STACK_INCLUSIVE) != 0) {
                      index--;
                      // Consume all following entries that match.
                      while (index >= 0) {
                          BackStackRecord bss = mBackStack.get(index);
                          if ((name != null && name.equals(bss.getName()))
                                  || (id >= 0 && id == bss.mIndex)) {
                              index--;
                              continue;
                          }
                          break;
                      }
                  }
              }
              if (index == mBackStack.size()-1) {
                  return false;
              }
              for (int i = mBackStack.size() - 1; i > index; i--) {
                  records.add(mBackStack.remove(i));
                  isRecordPop.add(true);
              }
          }
          return true;
      }
  
      FragmentManagerNonConfig retainNonConfig() {
          setRetaining(mSavedNonConfig);
          return mSavedNonConfig;
      }
  
      /**
       * Recurse the FragmentManagerNonConfig fragments and set the mRetaining to true. This
       * was previously done while saving the non-config state, but that has been moved to
       * {@link #saveNonConfig()} called from {@link #saveAllState()}. If mRetaining is set too
       * early, the fragment won't be destroyed when the FragmentManager is destroyed.
       */
      private static void setRetaining(FragmentManagerNonConfig nonConfig) {
          if (nonConfig == null) {
              return;
          }
          List<Fragment> fragments = nonConfig.getFragments();
          if (fragments != null) {
              for (Fragment fragment : fragments) {
                  fragment.mRetaining = true;
              }
          }
          List<FragmentManagerNonConfig> children = nonConfig.getChildNonConfigs();
          if (children != null) {
              for (FragmentManagerNonConfig child : children) {
                  setRetaining(child);
              }
          }
      }
  
      void saveNonConfig() {
          ArrayList<Fragment> fragments = null;
          ArrayList<FragmentManagerNonConfig> childFragments = null;
          if (mActive != null) {
              for (int i=0; i<mActive.size(); i++) {
                  Fragment f = mActive.valueAt(i);
                  if (f != null) {
                      if (f.mRetainInstance) {
                          if (fragments == null) {
                              fragments = new ArrayList<>();
                          }
                          fragments.add(f);
                          f.mTargetIndex = f.mTarget != null ? f.mTarget.mIndex : -1;
                          if (DEBUG) Log.v(TAG, "retainNonConfig: keeping retained " + f);
                      }
                      FragmentManagerNonConfig child;
                      if (f.mChildFragmentManager != null) {
                          f.mChildFragmentManager.saveNonConfig();
                          child = f.mChildFragmentManager.mSavedNonConfig;
                      } else {
                          // f.mChildNonConfig may be not null, when the parent fragment is
                          // in the backstack.
                          child = f.mChildNonConfig;
                      }
  
                      if (childFragments == null && child != null) {
                          childFragments = new ArrayList<>(mActive.size());
                          for (int j = 0; j < i; j++) {
                              childFragments.add(null);
                          }
                      }
  
                      if (childFragments != null) {
                          childFragments.add(child);
                      }
                  }
              }
          }
          if (fragments == null && childFragments == null) {
              mSavedNonConfig = null;
          } else {
              mSavedNonConfig = new FragmentManagerNonConfig(fragments, childFragments);
          }
      }
      
      void saveFragmentViewState(Fragment f) {
          if (f.mView == null) {
              return;
          }
          if (mStateArray == null) {
              mStateArray = new SparseArray<Parcelable>();
          } else {
              mStateArray.clear();
          }
          f.mView.saveHierarchyState(mStateArray);
          if (mStateArray.size() > 0) {
              f.mSavedViewState = mStateArray;
              mStateArray = null;
          }
      }
      
      Bundle saveFragmentBasicState(Fragment f) {
          Bundle result = null;
  
          if (mStateBundle == null) {
              mStateBundle = new Bundle();
          }
          f.performSaveInstanceState(mStateBundle);
          dispatchOnFragmentSaveInstanceState(f, mStateBundle, false);
          if (!mStateBundle.isEmpty()) {
              result = mStateBundle;
              mStateBundle = null;
          }
  
          if (f.mView != null) {
              saveFragmentViewState(f);
          }
          if (f.mSavedViewState != null) {
              if (result == null) {
                  result = new Bundle();
              }
              result.putSparseParcelableArray(
                      FragmentManagerImpl.VIEW_STATE_TAG, f.mSavedViewState);
          }
          if (!f.mUserVisibleHint) {
              if (result == null) {
                  result = new Bundle();
              }
              // Only add this if it's not the default value
              result.putBoolean(FragmentManagerImpl.USER_VISIBLE_HINT_TAG, f.mUserVisibleHint);
          }
  
          return result;
      }
  
      Parcelable saveAllState() {
          // Make sure all pending operations have now been executed to get
          // our state update-to-date.
          forcePostponedTransactions();
          endAnimatingAwayFragments();
          execPendingActions();
  
          mStateSaved = true;
          mSavedNonConfig = null;
  
          if (mActive == null || mActive.size() <= 0) {
              return null;
          }
          
          // First collect all active fragments.
          int N = mActive.size();
          FragmentState[] active = new FragmentState[N];
          boolean haveFragments = false;
          for (int i=0; i<N; i++) {
              Fragment f = mActive.valueAt(i);
              if (f != null) {
                  if (f.mIndex < 0) {
                      throwException(new IllegalStateException(
                              "Failure saving state: active " + f
                              + " has cleared index: " + f.mIndex));
                  }
  
                  haveFragments = true;
  
                  FragmentState fs = new FragmentState(f);
                  active[i] = fs;
                  
                  if (f.mState > Fragment.INITIALIZING && fs.mSavedFragmentState == null) {
                      fs.mSavedFragmentState = saveFragmentBasicState(f);
  
                      if (f.mTarget != null) {
                          if (f.mTarget.mIndex < 0) {
                              throwException(new IllegalStateException(
                                      "Failure saving state: " + f
                                      + " has target not in fragment manager: " + f.mTarget));
                          }
                          if (fs.mSavedFragmentState == null) {
                              fs.mSavedFragmentState = new Bundle();
                          }
                          putFragment(fs.mSavedFragmentState,
                                  FragmentManagerImpl.TARGET_STATE_TAG, f.mTarget);
                          if (f.mTargetRequestCode != 0) {
                              fs.mSavedFragmentState.putInt(
                                      FragmentManagerImpl.TARGET_REQUEST_CODE_STATE_TAG,
                                      f.mTargetRequestCode);
                          }
                      }
  
                  } else {
                      fs.mSavedFragmentState = f.mSavedFragmentState;
                  }
                  
                  if (DEBUG) Log.v(TAG, "Saved state of " + f + ": "
                          + fs.mSavedFragmentState);
              }
          }
          
          if (!haveFragments) {
              if (DEBUG) Log.v(TAG, "saveAllState: no fragments!");
              return null;
          }
          
          int[] added = null;
          BackStackState[] backStack = null;
          
          // Build list of currently added fragments.
          N = mAdded.size();
          if (N > 0) {
              added = new int[N];
              for (int i=0; i<N; i++) {
                  added[i] = mAdded.get(i).mIndex;
                  if (added[i] < 0) {
                      throwException(new IllegalStateException(
                              "Failure saving state: active " + mAdded.get(i)
                              + " has cleared index: " + added[i]));
                  }
                  if (DEBUG) Log.v(TAG, "saveAllState: adding fragment #" + i
                          + ": " + mAdded.get(i));
              }
          }
  
          // Now save back stack.
          if (mBackStack != null) {
              N = mBackStack.size();
              if (N > 0) {
                  backStack = new BackStackState[N];
                  for (int i=0; i<N; i++) {
                      backStack[i] = new BackStackState(this, mBackStack.get(i));
                      if (DEBUG) Log.v(TAG, "saveAllState: adding back stack #" + i
                              + ": " + mBackStack.get(i));
                  }
              }
          }
          
          FragmentManagerState fms = new FragmentManagerState();
          fms.mActive = active;
          fms.mAdded = added;
          fms.mBackStack = backStack;
          fms.mNextFragmentIndex = mNextFragmentIndex;
          if (mPrimaryNav != null) {
              fms.mPrimaryNavActiveIndex = mPrimaryNav.mIndex;
          }
          saveNonConfig();
          return fms;
      }
      
      void restoreAllState(Parcelable state, FragmentManagerNonConfig nonConfig) {
          // If there is no saved state at all, then there can not be
          // any nonConfig fragments either, so that is that.
          if (state == null) return;
          FragmentManagerState fms = (FragmentManagerState)state;
          if (fms.mActive == null) return;
  
          List<FragmentManagerNonConfig> childNonConfigs = null;
  
          // First re-attach any non-config instances we are retaining back
          // to their saved state, so we don't try to instantiate them again.
          if (nonConfig != null) {
              List<Fragment> nonConfigFragments = nonConfig.getFragments();
              childNonConfigs = nonConfig.getChildNonConfigs();
              final int count = nonConfigFragments != null ? nonConfigFragments.size() : 0;
              for (int i = 0; i < count; i++) {
                  Fragment f = nonConfigFragments.get(i);
                  if (DEBUG) Log.v(TAG, "restoreAllState: re-attaching retained " + f);
                  int index = 0; // index of f in fms.mActive
                  while (index < fms.mActive.length && fms.mActive[index].mIndex != f.mIndex) {
                      index++;
                  }
                  if (index == fms.mActive.length) {
                      throwException(new IllegalStateException("Could not find active fragment "
                              + "with index " + f.mIndex));
                  }
                  FragmentState fs = fms.mActive[index];
                  fs.mInstance = f;
                  f.mSavedViewState = null;
                  f.mBackStackNesting = 0;
                  f.mInLayout = false;
                  f.mAdded = false;
                  f.mTarget = null;
                  if (fs.mSavedFragmentState != null) {
                      fs.mSavedFragmentState.setClassLoader(mHost.getContext().getClassLoader());
                      f.mSavedViewState = fs.mSavedFragmentState.getSparseParcelableArray(
                              FragmentManagerImpl.VIEW_STATE_TAG);
                      f.mSavedFragmentState = fs.mSavedFragmentState;
                  }
              }
          }
          
          // Build the full list of active fragments, instantiating them from
          // their saved state.
          mActive = new SparseArray<>(fms.mActive.length);
          for (int i=0; i<fms.mActive.length; i++) {
              FragmentState fs = fms.mActive[i];
              if (fs != null) {
                  FragmentManagerNonConfig childNonConfig = null;
                  if (childNonConfigs != null && i < childNonConfigs.size()) {
                      childNonConfig = childNonConfigs.get(i);
                  }
                  Fragment f = fs.instantiate(mHost, mContainer, mParent, childNonConfig);
                  if (DEBUG) Log.v(TAG, "restoreAllState: active #" + i + ": " + f);
                  mActive.put(f.mIndex, f);
                  // Now that the fragment is instantiated (or came from being
                  // retained above), clear mInstance in case we end up re-restoring
                  // from this FragmentState again.
                  fs.mInstance = null;
              }
          }
          
          // Update the target of all retained fragments.
          if (nonConfig != null) {
              List<Fragment> nonConfigFragments = nonConfig.getFragments();
              final int count = nonConfigFragments != null ? nonConfigFragments.size() : 0;
              for (int i = 0; i < count; i++) {
                  Fragment f = nonConfigFragments.get(i);
                  if (f.mTargetIndex >= 0) {
                      f.mTarget = mActive.get(f.mTargetIndex);
                      if (f.mTarget == null) {
                          Log.w(TAG, "Re-attaching retained fragment " + f
                                  + " target no longer exists: " + f.mTargetIndex);
                          f.mTarget = null;
                      }
                  }
              }
          }
  
          // Build the list of currently added fragments.
          mAdded.clear();
          if (fms.mAdded != null) {
              for (int i=0; i<fms.mAdded.length; i++) {
                  Fragment f = mActive.get(fms.mAdded[i]);
                  if (f == null) {
                      throwException(new IllegalStateException(
                              "No instantiated fragment for index #" + fms.mAdded[i]));
                  }
                  f.mAdded = true;
                  if (DEBUG) Log.v(TAG, "restoreAllState: added #" + i + ": " + f);
                  if (mAdded.contains(f)) {
                      throw new IllegalStateException("Already added!");
                  }
                  synchronized (mAdded) {
                      mAdded.add(f);
                  }
              }
          }
          
          // Build the back stack.
          if (fms.mBackStack != null) {
              mBackStack = new ArrayList<BackStackRecord>(fms.mBackStack.length);
              for (int i=0; i<fms.mBackStack.length; i++) {
                  BackStackRecord bse = fms.mBackStack[i].instantiate(this);
                  if (DEBUG) {
                      Log.v(TAG, "restoreAllState: back stack #" + i
                          + " (index " + bse.mIndex + "): " + bse);
                      LogWriter logw = new LogWriter(Log.VERBOSE, TAG);
                      PrintWriter pw = new FastPrintWriter(logw, false, 1024);
                      bse.dump("  ", pw, false);
                      pw.flush();
                  }
                  mBackStack.add(bse);
                  if (bse.mIndex >= 0) {
                      setBackStackIndex(bse.mIndex, bse);
                  }
              }
          } else {
              mBackStack = null;
          }
  
          if (fms.mPrimaryNavActiveIndex >= 0) {
              mPrimaryNav = mActive.get(fms.mPrimaryNavActiveIndex);
          }
  
          mNextFragmentIndex = fms.mNextFragmentIndex;
      }
  
      /**
       * To prevent list modification errors, mActive sets values to null instead of
       * removing them when the Fragment becomes inactive. This cleans up the list at the
       * end of executing the transactions.
       */
      private void burpActive() {
          if (mActive != null) {
              for (int i = mActive.size() - 1; i >= 0; i--) {
                  if (mActive.valueAt(i) == null) {
                      mActive.delete(mActive.keyAt(i));
                  }
              }
          }
      }
  
      public void attachController(FragmentHostCallback<?> host, FragmentContainer container,
              Fragment parent) {
          if (mHost != null) throw new IllegalStateException("Already attached");
          mHost = host;
          mContainer = container;
          mParent = parent;
          mAllowOldReentrantBehavior = getTargetSdk() <= Build.VERSION_CODES.N_MR1;
      }
  
      /**
       * @return the target SDK of the FragmentManager's application info. If the
       * FragmentManager has been torn down, then 0 is returned.
       */
      int getTargetSdk() {
          if (mHost != null) {
              Context context = mHost.getContext();
              if (context != null) {
                  ApplicationInfo info = context.getApplicationInfo();
                  if (info != null) {
                      return info.targetSdkVersion;
                  }
              }
          }
          return 0;
      }
  
      @UnsupportedAppUsage
      public void noteStateNotSaved() {
          mSavedNonConfig = null;
          mStateSaved = false;
          final int addedCount = mAdded.size();
          for (int i = 0; i < addedCount; i++) {
              Fragment fragment = mAdded.get(i);
              if (fragment != null) {
                  fragment.noteStateNotSaved();
              }
          }
      }
  
      public void dispatchCreate() {
          mStateSaved = false;
          dispatchMoveToState(Fragment.CREATED);
      }
      
      public void dispatchActivityCreated() {
          mStateSaved = false;
          dispatchMoveToState(Fragment.ACTIVITY_CREATED);
      }
      
      public void dispatchStart() {
          mStateSaved = false;
          dispatchMoveToState(Fragment.STARTED);
      }
      
      public void dispatchResume() {
          mStateSaved = false;
          dispatchMoveToState(Fragment.RESUMED);
      }
      
      public void dispatchPause() {
          dispatchMoveToState(Fragment.STARTED);
      }
      
      public void dispatchStop() {
          dispatchMoveToState(Fragment.STOPPED);
      }
      
      public void dispatchDestroyView() {
          dispatchMoveToState(Fragment.CREATED);
      }
  
      public void dispatchDestroy() {
          mDestroyed = true;
          execPendingActions();
          dispatchMoveToState(Fragment.INITIALIZING);
          mHost = null;
          mContainer = null;
          mParent = null;
      }
  
      /**
       * This method is called by dispatch* methods to change the FragmentManager's state.
       * It calls moveToState directly if the target SDK is older than O. Otherwise, it sets and
       * clears mExecutingActions to ensure that there is no reentrancy while the
       * FragmentManager is changing state.
       *
       * @param state The new state of the FragmentManager.
       */
      private void dispatchMoveToState(int state) {
          if (mAllowOldReentrantBehavior) {
              moveToState(state, false);
          } else {
              try {
                  mExecutingActions = true;
                  moveToState(state, false);
              } finally {
                  mExecutingActions = false;
              }
          }
          execPendingActions();
      }
  
      /**
       * @deprecated use {@link #dispatchMultiWindowModeChanged(boolean, Configuration)}
       */
      @Deprecated
      public void dispatchMultiWindowModeChanged(boolean isInMultiWindowMode) {
          for (int i = mAdded.size() - 1; i >= 0; --i) {
              final Fragment f = mAdded.get(i);
              if (f != null) {
                  f.performMultiWindowModeChanged(isInMultiWindowMode);
              }
          }
      }
  
      public void dispatchMultiWindowModeChanged(boolean isInMultiWindowMode,
              Configuration newConfig) {
          for (int i = mAdded.size() - 1; i >= 0; --i) {
              final Fragment f = mAdded.get(i);
              if (f != null) {
                  f.performMultiWindowModeChanged(isInMultiWindowMode, newConfig);
              }
          }
      }
  
      /**
       * @deprecated use {@link #dispatchPictureInPictureModeChanged(boolean, Configuration)}
       */
      @Deprecated
      public void dispatchPictureInPictureModeChanged(boolean isInPictureInPictureMode) {
          for (int i = mAdded.size() - 1; i >= 0; --i) {
              final Fragment f = mAdded.get(i);
              if (f != null) {
                  f.performPictureInPictureModeChanged(isInPictureInPictureMode);
              }
          }
      }
  
      public void dispatchPictureInPictureModeChanged(boolean isInPictureInPictureMode,
              Configuration newConfig) {
          for (int i = mAdded.size() - 1; i >= 0; --i) {
              final Fragment f = mAdded.get(i);
              if (f != null) {
                  f.performPictureInPictureModeChanged(isInPictureInPictureMode, newConfig);
              }
          }
      }
  
      public void dispatchConfigurationChanged(Configuration newConfig) {
          for (int i = 0; i < mAdded.size(); i++) {
              Fragment f = mAdded.get(i);
              if (f != null) {
                  f.performConfigurationChanged(newConfig);
              }
          }
      }
  
      public void dispatchLowMemory() {
          for (int i = 0; i < mAdded.size(); i++) {
              Fragment f = mAdded.get(i);
              if (f != null) {
                  f.performLowMemory();
              }
          }
      }
  
      public void dispatchTrimMemory(int level) {
          for (int i = 0; i < mAdded.size(); i++) {
              Fragment f = mAdded.get(i);
              if (f != null) {
                  f.performTrimMemory(level);
              }
          }
      }
  
      public boolean dispatchCreateOptionsMenu(Menu menu, MenuInflater inflater) {
          if (mCurState < Fragment.CREATED) {
              return false;
          }
          boolean show = false;
          ArrayList<Fragment> newMenus = null;
          for (int i = 0; i < mAdded.size(); i++) {
              Fragment f = mAdded.get(i);
              if (f != null) {
                  if (f.performCreateOptionsMenu(menu, inflater)) {
                      show = true;
                      if (newMenus == null) {
                          newMenus = new ArrayList<Fragment>();
                      }
                      newMenus.add(f);
                  }
              }
          }
  
          if (mCreatedMenus != null) {
              for (int i=0; i<mCreatedMenus.size(); i++) {
                  Fragment f = mCreatedMenus.get(i);
                  if (newMenus == null || !newMenus.contains(f)) {
                      f.onDestroyOptionsMenu();
                  }
              }
          }
          
          mCreatedMenus = newMenus;
          
          return show;
      }
      
      public boolean dispatchPrepareOptionsMenu(Menu menu) {
          if (mCurState < Fragment.CREATED) {
              return false;
          }
          boolean show = false;
          for (int i = 0; i < mAdded.size(); i++) {
              Fragment f = mAdded.get(i);
              if (f != null) {
                  if (f.performPrepareOptionsMenu(menu)) {
                      show = true;
                  }
              }
          }
          return show;
      }
      
      public boolean dispatchOptionsItemSelected(MenuItem item) {
          if (mCurState < Fragment.CREATED) {
              return false;
          }
          for (int i = 0; i < mAdded.size(); i++) {
              Fragment f = mAdded.get(i);
              if (f != null) {
                  if (f.performOptionsItemSelected(item)) {
                      return true;
                  }
              }
          }
          return false;
      }
      
      public boolean dispatchContextItemSelected(MenuItem item) {
          if (mCurState < Fragment.CREATED) {
              return false;
          }
          for (int i = 0; i < mAdded.size(); i++) {
              Fragment f = mAdded.get(i);
              if (f != null) {
                  if (f.performContextItemSelected(item)) {
                      return true;
                  }
              }
          }
          return false;
      }
      
      public void dispatchOptionsMenuClosed(Menu menu) {
          if (mCurState < Fragment.CREATED) {
              return;
          }
          for (int i = 0; i < mAdded.size(); i++) {
              Fragment f = mAdded.get(i);
              if (f != null) {
                  f.performOptionsMenuClosed(menu);
              }
          }
      }
  
      @SuppressWarnings("ReferenceEquality")
      public void setPrimaryNavigationFragment(Fragment f) {
          if (f != null && (mActive.get(f.mIndex) != f
                  || (f.mHost != null && f.getFragmentManager() != this))) {
              throw new IllegalArgumentException("Fragment " + f
                      + " is not an active fragment of FragmentManager " + this);
          }
          mPrimaryNav = f;
      }
  
      public Fragment getPrimaryNavigationFragment() {
          return mPrimaryNav;
      }
  
      public void registerFragmentLifecycleCallbacks(FragmentLifecycleCallbacks cb,
              boolean recursive) {
          mLifecycleCallbacks.add(new Pair<>(cb, recursive));
      }
  
      public void unregisterFragmentLifecycleCallbacks(FragmentLifecycleCallbacks cb) {
          synchronized (mLifecycleCallbacks) {
              for (int i = 0, N = mLifecycleCallbacks.size(); i < N; i++) {
                  if (mLifecycleCallbacks.get(i).first == cb) {
                      mLifecycleCallbacks.remove(i);
                      break;
                  }
              }
          }
      }
  
      void dispatchOnFragmentPreAttached(Fragment f, Context context, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentPreAttached(f, context, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentPreAttached(this, f, context);
              }
          }
      }
  
      void dispatchOnFragmentAttached(Fragment f, Context context, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentAttached(f, context, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentAttached(this, f, context);
              }
          }
      }
  
      void dispatchOnFragmentPreCreated(Fragment f, Bundle savedInstanceState,
              boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentPreCreated(f, savedInstanceState, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentPreCreated(this, f, savedInstanceState);
              }
          }
      }
  
      void dispatchOnFragmentCreated(Fragment f, Bundle savedInstanceState, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentCreated(f, savedInstanceState, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentCreated(this, f, savedInstanceState);
              }
          }
      }
  
      void dispatchOnFragmentActivityCreated(Fragment f, Bundle savedInstanceState,
              boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentActivityCreated(f, savedInstanceState, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentActivityCreated(this, f, savedInstanceState);
              }
          }
      }
  
      void dispatchOnFragmentViewCreated(Fragment f, View v, Bundle savedInstanceState,
              boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentViewCreated(f, v, savedInstanceState, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentViewCreated(this, f, v, savedInstanceState);
              }
          }
      }
  
      void dispatchOnFragmentStarted(Fragment f, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentStarted(f, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentStarted(this, f);
              }
          }
      }
  
      void dispatchOnFragmentResumed(Fragment f, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentResumed(f, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentResumed(this, f);
              }
          }
      }
  
      void dispatchOnFragmentPaused(Fragment f, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentPaused(f, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentPaused(this, f);
              }
          }
      }
  
      void dispatchOnFragmentStopped(Fragment f, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentStopped(f, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentStopped(this, f);
              }
          }
      }
  
      void dispatchOnFragmentSaveInstanceState(Fragment f, Bundle outState, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentSaveInstanceState(f, outState, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentSaveInstanceState(this, f, outState);
              }
          }
      }
  
      void dispatchOnFragmentViewDestroyed(Fragment f, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentViewDestroyed(f, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentViewDestroyed(this, f);
              }
          }
      }
  
      void dispatchOnFragmentDestroyed(Fragment f, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentDestroyed(f, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentDestroyed(this, f);
              }
          }
      }
  
      void dispatchOnFragmentDetached(Fragment f, boolean onlyRecursive) {
          if (mParent != null) {
              FragmentManager parentManager = mParent.getFragmentManager();
              if (parentManager instanceof FragmentManagerImpl) {
                  ((FragmentManagerImpl) parentManager)
                          .dispatchOnFragmentDetached(f, true);
              }
          }
          for (Pair<FragmentLifecycleCallbacks, Boolean> p : mLifecycleCallbacks) {
              if (!onlyRecursive || p.second) {
                  p.first.onFragmentDetached(this, f);
              }
          }
      }
  
      @Override
      public void invalidateOptionsMenu() {
          if (mHost != null && mCurState == Fragment.RESUMED) {
              mHost.onInvalidateOptionsMenu();
          } else {
              mNeedMenuInvalidate = true;
          }
      }
  
      public static int reverseTransit(int transit) {
          int rev = 0;
          switch (transit) {
              case FragmentTransaction.TRANSIT_FRAGMENT_OPEN:
                  rev = FragmentTransaction.TRANSIT_FRAGMENT_CLOSE;
                  break;
              case FragmentTransaction.TRANSIT_FRAGMENT_CLOSE:
                  rev = FragmentTransaction.TRANSIT_FRAGMENT_OPEN;
                  break;
              case FragmentTransaction.TRANSIT_FRAGMENT_FADE:
                  rev = FragmentTransaction.TRANSIT_FRAGMENT_FADE;
                  break;
          }
          return rev;
          
      }
      
      public static int transitToStyleIndex(int transit, boolean enter) {
          int animAttr = -1;
          switch (transit) {
              case FragmentTransaction.TRANSIT_FRAGMENT_OPEN:
                  animAttr = enter
                      ? com.android.internal.R.styleable.FragmentAnimation_fragmentOpenEnterAnimation
                      : com.android.internal.R.styleable.FragmentAnimation_fragmentOpenExitAnimation;
                  break;
              case FragmentTransaction.TRANSIT_FRAGMENT_CLOSE:
                  animAttr = enter
                      ? com.android.internal.R.styleable.FragmentAnimation_fragmentCloseEnterAnimation
                      : com.android.internal.R.styleable.FragmentAnimation_fragmentCloseExitAnimation;
                  break;
              case FragmentTransaction.TRANSIT_FRAGMENT_FADE:
                  animAttr = enter
                      ? com.android.internal.R.styleable.FragmentAnimation_fragmentFadeEnterAnimation
                      : com.android.internal.R.styleable.FragmentAnimation_fragmentFadeExitAnimation;
                  break;
          }
          return animAttr;
      }
  
      @Override
      public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
          if (!"fragment".equals(name)) {
              return null;
          }
  
          String fname = attrs.getAttributeValue(null, "class");
          TypedArray a =
                  context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.Fragment);
          if (fname == null) {
              fname = a.getString(com.android.internal.R.styleable.Fragment_name);
          }
          int id = a.getResourceId(com.android.internal.R.styleable.Fragment_id, View.NO_ID);
          String tag = a.getString(com.android.internal.R.styleable.Fragment_tag);
          a.recycle();
  
          int containerId = parent != null ? parent.getId() : 0;
          if (containerId == View.NO_ID && id == View.NO_ID && tag == null) {
              throw new IllegalArgumentException(attrs.getPositionDescription()
                      + ": Must specify unique android:id, android:tag, or have a parent with"
                      + " an id for " + fname);
          }
  
          // If we restored from a previous state, we may already have
          // instantiated this fragment from the state and should use
          // that instance instead of making a new one.
          Fragment fragment = id != View.NO_ID ? findFragmentById(id) : null;
          if (fragment == null && tag != null) {
              fragment = findFragmentByTag(tag);
          }
          if (fragment == null && containerId != View.NO_ID) {
              fragment = findFragmentById(containerId);
          }
  
          if (FragmentManagerImpl.DEBUG) Log.v(TAG, "onCreateView: id=0x"
                  + Integer.toHexString(id) + " fname=" + fname
                  + " existing=" + fragment);
          if (fragment == null) {
              fragment = mContainer.instantiate(context, fname, null);
              fragment.mFromLayout = true;
              fragment.mFragmentId = id != 0 ? id : containerId;
              fragment.mContainerId = containerId;
              fragment.mTag = tag;
              fragment.mInLayout = true;
              fragment.mFragmentManager = this;
              fragment.mHost = mHost;
              fragment.onInflate(mHost.getContext(), attrs, fragment.mSavedFragmentState);
              addFragment(fragment, true);
          } else if (fragment.mInLayout) {
              // A fragment already exists and it is not one we restored from
              // previous state.
              throw new IllegalArgumentException(attrs.getPositionDescription()
                      + ": Duplicate id 0x" + Integer.toHexString(id)
                      + ", tag " + tag + ", or parent id 0x" + Integer.toHexString(containerId)
                      + " with another fragment for " + fname);
          } else {
              // This fragment was retained from a previous instance; get it
              // going now.
              fragment.mInLayout = true;
              fragment.mHost = mHost;
              // If this fragment is newly instantiated (either right now, or
              // from last saved state), then give it the attributes to
              // initialize itself.
              if (!fragment.mRetaining) {
                  fragment.onInflate(mHost.getContext(), attrs, fragment.mSavedFragmentState);
              }
          }
  
          // If we haven't finished entering the CREATED state ourselves yet,
          // push the inflated child fragment along. This will ensureInflatedFragmentView
          // at the right phase of the lifecycle so that we will have mView populated
          // for compliant fragments below.
          if (mCurState < Fragment.CREATED && fragment.mFromLayout) {
              moveToState(fragment, Fragment.CREATED, 0, 0, false);
          } else {
              moveToState(fragment);
          }
  
          if (fragment.mView == null) {
              throw new IllegalStateException("Fragment " + fname
                      + " did not create a view.");
          }
          if (id != 0) {
              fragment.mView.setId(id);
          }
          if (fragment.mView.getTag() == null) {
              fragment.mView.setTag(tag);
          }
          return fragment.mView;
      }
  
      @Override
      public View onCreateView(String name, Context context, AttributeSet attrs) {
          return null;
      }
  
      LayoutInflater.Factory2 getLayoutInflaterFactory() {
          return this;
      }
  
      /**
       * An add or pop transaction to be scheduled for the UI thread.
       */
      interface OpGenerator {
          /**
           * Generate transactions to add to {@code records} and whether or not the transaction is
           * an add or pop to {@code isRecordPop}.
           *
           * records and isRecordPop must be added equally so that each transaction in records
           * matches the boolean for whether or not it is a pop in isRecordPop.
           *
           * @param records A list to add transactions to.
           * @param isRecordPop A list to add whether or not the transactions added to records is
           *                    a pop transaction.
           * @return true if something was added or false otherwise.
           */
          boolean generateOps(ArrayList<BackStackRecord> records, ArrayList<Boolean> isRecordPop);
      }
  
      /**
       * A pop operation OpGenerator. This will be run on the UI thread and will generate the
       * transactions that will be popped if anything can be popped.
       */
      private class PopBackStackState implements OpGenerator {
          final String mName;
          final int mId;
          final int mFlags;
  
          public PopBackStackState(String name, int id, int flags) {
              mName = name;
              mId = id;
              mFlags = flags;
          }
  
          @Override
          public boolean generateOps(ArrayList<BackStackRecord> records,
                  ArrayList<Boolean> isRecordPop) {
              if (mPrimaryNav != null // We have a primary nav fragment
                      && mId < 0 // No valid id (since they're local)
                      && mName == null) { // no name to pop to (since they're local)
                  final FragmentManager childManager = mPrimaryNav.mChildFragmentManager;
                  if (childManager != null && childManager.popBackStackImmediate()) {
                      // We didn't add any operations for this FragmentManager even though
                      // a child did do work.
                      return false;
                  }
              }
              return popBackStackState(records, isRecordPop, mName, mId, mFlags);
          }
      }
  
      /**
       * A listener for a postponed transaction. This waits until
       * {@link Fragment#startPostponedEnterTransition()} is called or a transaction is started
       * that interacts with this one, based on interactions with the fragment container.
       */
      static class StartEnterTransitionListener
              implements Fragment.OnStartEnterTransitionListener {
          private final boolean mIsBack;
          private final BackStackRecord mRecord;
          private int mNumPostponed;
  
          public StartEnterTransitionListener(BackStackRecord record, boolean isBack) {
              mIsBack = isBack;
              mRecord = record;
          }
  
          /**
           * Called from {@link Fragment#startPostponedEnterTransition()}, this decreases the
           * number of Fragments that are postponed. This may cause the transaction to schedule
           * to finish running and run transitions and animations.
           */
          @Override
          public void onStartEnterTransition() {
              mNumPostponed--;
              if (mNumPostponed != 0) {
                  return;
              }
              mRecord.mManager.scheduleCommit();
          }
  
          /**
           * Called from {@link Fragment#
           * setOnStartEnterTransitionListener(Fragment.OnStartEnterTransitionListener)}, this
           * increases the number of fragments that are postponed as part of this transaction.
           */
          @Override
          public void startListening() {
              mNumPostponed++;
          }
  
          /**
           * @return true if there are no more postponed fragments as part of the transaction.
           */
          public boolean isReady() {
              return mNumPostponed == 0;
          }
  
          /**
           * Completes the transaction and start the animations and transitions. This may skip
           * the transitions if this is called before all fragments have called
           * {@link Fragment#startPostponedEnterTransition()}.
           */
          public void completeTransaction() {
              final boolean canceled;
              canceled = mNumPostponed > 0;
              FragmentManagerImpl manager = mRecord.mManager;
              final int numAdded = manager.mAdded.size();
              for (int i = 0; i < numAdded; i++) {
                  final Fragment fragment = manager.mAdded.get(i);
                  fragment.setOnStartEnterTransitionListener(null);
                  if (canceled && fragment.isPostponed()) {
                      fragment.startPostponedEnterTransition();
                  }
              }
              mRecord.mManager.completeExecute(mRecord, mIsBack, !canceled, true);
          }
  
          /**
           * Cancels this transaction instead of completing it. That means that the state isn't
           * changed, so the pop results in no change to the state.
           */
          public void cancelTransaction() {
              mRecord.mManager.completeExecute(mRecord, mIsBack, false, false);
          }
      }
  }
  