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.annotation.CallSuper;
  import android.annotation.NonNull;
  import android.annotation.Nullable;
  import android.annotation.StringRes;
  import android.annotation.UnsupportedAppUsage;
  import android.content.ComponentCallbacks2;
  import android.content.Context;
  import android.content.Intent;
  import android.content.IntentSender;
  import android.content.res.Configuration;
  import android.content.res.Resources;
  import android.content.res.TypedArray;
  import android.os.Build;
  import android.os.Build.VERSION_CODES;
  import android.os.Bundle;
  import android.os.Looper;
  import android.os.Parcel;
  import android.os.Parcelable;
  import android.os.UserHandle;
  import android.transition.Transition;
  import android.transition.TransitionInflater;
  import android.transition.TransitionSet;
  import android.util.AndroidRuntimeException;
  import android.util.ArrayMap;
  import android.util.AttributeSet;
  import android.util.DebugUtils;
  import android.util.SparseArray;
  import android.util.SuperNotCalledException;
  import android.view.ContextMenu;
  import android.view.ContextMenu.ContextMenuInfo;
  import android.view.LayoutInflater;
  import android.view.Menu;
  import android.view.MenuInflater;
  import android.view.MenuItem;
  import android.view.View;
  import android.view.View.OnCreateContextMenuListener;
  import android.view.ViewGroup;
  import android.widget.AdapterView;
  
  import java.io.FileDescriptor;
  import java.io.PrintWriter;
  import java.lang.reflect.InvocationTargetException;
  
  /**
   * A Fragment is a piece of an application's user interface or behavior
   * that can be placed in an {@link Activity}.  Interaction with fragments
   * is done through {@link FragmentManager}, which can be obtained via
   * {@link Activity#getFragmentManager() Activity.getFragmentManager()} and
   * {@link Fragment#getFragmentManager() Fragment.getFragmentManager()}.
   *
   * <p>The Fragment class can be used many ways to achieve a wide variety of
   * results. In its core, it represents a particular operation or interface
   * that is running within a larger {@link Activity}.  A Fragment is closely
   * tied to the Activity it is in, and can not be used apart from one.  Though
   * Fragment defines its own lifecycle, that lifecycle is dependent on its
   * activity: if the activity is stopped, no fragments inside of it can be
   * started; when the activity is destroyed, all fragments will be destroyed.
   *
   * <p>All subclasses of Fragment must include a public no-argument constructor.
   * The framework will often re-instantiate a fragment class when needed,
   * in particular during state restore, and needs to be able to find this
   * constructor to instantiate it.  If the no-argument constructor is not
   * available, a runtime exception will occur in some cases during state
   * restore.
   *
   * <p>Topics covered here:
   * <ol>
   * <li><a href="#OlderPlatforms">Older Platforms</a>
   * <li><a href="#Lifecycle">Lifecycle</a>
   * <li><a href="#Layout">Layout</a>
   * <li><a href="#BackStack">Back Stack</a>
   * </ol>
   *
   * <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>
   *
   * <a name="OlderPlatforms"></a>
   * <h3>Older Platforms</h3>
   *
   * While the Fragment 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.
   *
   * <a name="Lifecycle"></a>
   * <h3>Lifecycle</h3>
   *
   * <p>Though a Fragment's lifecycle is tied to its owning activity, it has
   * its own wrinkle on the standard activity lifecycle.  It includes basic
   * activity lifecycle methods such as {@link #onResume}, but also important
   * are methods related to interactions with the activity and UI generation.
   *
   * <p>The core series of lifecycle methods that are called to bring a fragment
   * up to resumed state (interacting with the user) are:
   *
   * <ol>
   * <li> {@link #onAttach} called once the fragment is associated with its activity.
   * <li> {@link #onCreate} called to do initial creation of the fragment.
   * <li> {@link #onCreateView} creates and returns the view hierarchy associated
   * with the fragment.
   * <li> {@link #onActivityCreated} tells the fragment that its activity has
   * completed its own {@link Activity#onCreate Activity.onCreate()}.
   * <li> {@link #onViewStateRestored} tells the fragment that all of the saved
   * state of its view hierarchy has been restored.
   * <li> {@link #onStart} makes the fragment visible to the user (based on its
   * containing activity being started).
   * <li> {@link #onResume} makes the fragment begin interacting with the user
   * (based on its containing activity being resumed).
   * </ol>
   *
   * <p>As a fragment is no longer being used, it goes through a reverse
   * series of callbacks:
   *
   * <ol>
   * <li> {@link #onPause} fragment is no longer interacting with the user either
   * because its activity is being paused or a fragment operation is modifying it
   * in the activity.
   * <li> {@link #onStop} fragment is no longer visible to the user either
   * because its activity is being stopped or a fragment operation is modifying it
   * in the activity.
   * <li> {@link #onDestroyView} allows the fragment to clean up resources
   * associated with its View.
   * <li> {@link #onDestroy} called to do final cleanup of the fragment's state.
   * <li> {@link #onDetach} called immediately prior to the fragment no longer
   * being associated with its activity.
   * </ol>
   *
   * <a name="Layout"></a>
   * <h3>Layout</h3>
   *
   * <p>Fragments can be used as part of your application's layout, allowing
   * you to better modularize your code and more easily adjust your user
   * interface to the screen it is running on.  As an example, we can look
   * at a simple program consisting of a list of items, and display of the
   * details of each item.</p>
   *
   * <p>An activity's layout XML can include <code>&lt;fragment&gt;</code> tags
   * to embed fragment instances inside of the layout.  For example, here is
   * a simple layout that embeds one fragment:</p>
   *
   * {@sample development/samples/ApiDemos/res/layout/fragment_layout.xml layout}
   *
   * <p>The layout is installed in the activity in the normal way:</p>
   *
   * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
   *      main}
   *
   * <p>The titles fragment, showing a list of titles, is fairly simple, relying
   * on {@link ListFragment} for most of its work.  Note the implementation of
   * clicking an item: depending on the current activity's layout, it can either
   * create and display a new fragment to show the details in-place (more about
   * this later), or start a new activity to show the details.</p>
   *
   * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
   *      titles}
   *
   * <p>The details fragment showing the contents of a selected item just
   * displays a string of text based on an index of a string array built in to
   * the app:</p>
   *
   * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
   *      details}
   *
   * <p>In this case when the user clicks on a title, there is no details
   * container in the current activity, so the titles fragment's click code will
   * launch a new activity to display the details fragment:</p>
   *
   * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java
   *      details_activity}
   *
   * <p>However the screen may be large enough to show both the list of titles
   * and details about the currently selected title.  To use such a layout on
   * a landscape screen, this alternative layout can be placed under layout-land:</p>
   *
   * {@sample development/samples/ApiDemos/res/layout-land/fragment_layout.xml layout}
   *
   * <p>Note how the prior code will adjust to this alternative UI flow: the titles
   * fragment will now embed the details fragment inside of this activity, and the
   * details activity will finish itself if it is running in a configuration
   * where the details can be shown in-place.
   *
   * <p>When a configuration change causes the activity hosting these fragments
   * to restart, its new instance may use a different layout that doesn't
   * include the same fragments as the previous layout.  In this case all of
   * the previous fragments will still be instantiated and running in the new
   * instance.  However, any that are no longer associated with a &lt;fragment&gt;
   * tag in the view hierarchy will not have their content view created
   * and will return false from {@link #isInLayout}.  (The code here also shows
   * how you can determine if a fragment placed in a container is no longer
   * running in a layout with that container and avoid creating its view hierarchy
   * in that case.)
   *
   * <p>The attributes of the &lt;fragment&gt; tag are used to control the
   * LayoutParams provided when attaching the fragment's view to the parent
   * container.  They can also be parsed by the fragment in {@link #onInflate}
   * as parameters.
   *
   * <p>The fragment being instantiated must have some kind of unique identifier
   * so that it can be re-associated with a previous instance if the parent
   * activity needs to be destroyed and recreated.  This can be provided these
   * ways:
   *
   * <ul>
   * <li>If nothing is explicitly supplied, the view ID of the container will
   * be used.
   * <li><code>android:tag</code> can be used in &lt;fragment&gt; to provide
   * a specific tag name for the fragment.
   * <li><code>android:id</code> can be used in &lt;fragment&gt; to provide
   * a specific identifier for the fragment.
   * </ul>
   *
   * <a name="BackStack"></a>
   * <h3>Back Stack</h3>
   *
   * <p>The transaction in which fragments are modified can be placed on an
   * internal back-stack of the owning activity.  When the user presses back
   * in the activity, any transactions on the back stack are popped off before
   * the activity itself is finished.
   *
   * <p>For example, consider this simple fragment that is instantiated with
   * an integer argument and displays that in a TextView in its UI:</p>
   *
   * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentStack.java
   *      fragment}
   *
   * <p>A function that creates a new instance of the fragment, replacing
   * whatever current fragment instance is being shown and pushing that change
   * on to the back stack could be written as:
   *
   * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentStack.java
   *      add_stack}
   *
   * <p>After each call to this function, a new entry is on the stack, and
   * pressing back will pop it to return the user to whatever previous state
   * the activity UI was in.
   *
   * @deprecated Use the <a href="{@docRoot}tools/extras/support-library.html">Support Library</a>
   *      {@link android.support.v4.app.Fragment} for consistent behavior across all devices
   *      and access to <a href="{@docRoot}topic/libraries/architecture/lifecycle.html">Lifecycle</a>.
   */
  @Deprecated
  public class Fragment implements ComponentCallbacks2, OnCreateContextMenuListener {
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
      private static final ArrayMap<String, Class<?>> sClassMap =
              new ArrayMap<String, Class<?>>();
  
      static final int INVALID_STATE = -1;   // Invalid state used as a null value.
      static final int INITIALIZING = 0;     // Not yet created.
      static final int CREATED = 1;          // Created.
      static final int ACTIVITY_CREATED = 2; // The activity has finished its creation.
      static final int STOPPED = 3;          // Fully created, not started.
      static final int STARTED = 4;          // Created and started, not resumed.
      static final int RESUMED = 5;          // Created started and resumed.
  
      private static final Transition USE_DEFAULT_TRANSITION = new TransitionSet();
  
      int mState = INITIALIZING;
  
      // When instantiated from saved state, this is the saved state.
      @UnsupportedAppUsage
      Bundle mSavedFragmentState;
      SparseArray<Parcelable> mSavedViewState;
  
      // Index into active fragment array.
      @UnsupportedAppUsage
      int mIndex = -1;
  
      // Internal unique name for this fragment;
      @UnsupportedAppUsage
      String mWho;
  
      // Construction arguments;
      Bundle mArguments;
  
      // Target fragment.
      Fragment mTarget;
  
      // For use when retaining a fragment: this is the index of the last mTarget.
      int mTargetIndex = -1;
  
      // Target request code.
      int mTargetRequestCode;
  
      // True if the fragment is in the list of added fragments.
      @UnsupportedAppUsage
      boolean mAdded;
  
      // If set this fragment is being removed from its activity.
      boolean mRemoving;
  
      // Set to true if this fragment was instantiated from a layout file.
      boolean mFromLayout;
  
      // Set to true when the view has actually been inflated in its layout.
      boolean mInLayout;
  
      // True if this fragment has been restored from previously saved state.
      boolean mRestored;
  
      // True if performCreateView has been called and a matching call to performDestroyView
      // has not yet happened.
      boolean mPerformedCreateView;
  
      // Number of active back stack entries this fragment is in.
      int mBackStackNesting;
  
      // The fragment manager we are associated with.  Set as soon as the
      // fragment is used in a transaction; cleared after it has been removed
      // from all transactions.
      @UnsupportedAppUsage
      FragmentManagerImpl mFragmentManager;
  
      // Activity this fragment is attached to.
      @UnsupportedAppUsage
      FragmentHostCallback mHost;
  
      // Private fragment manager for child fragments inside of this one.
      @UnsupportedAppUsage
      FragmentManagerImpl mChildFragmentManager;
  
      // For use when restoring fragment state and descendant fragments are retained.
      // This state is set by FragmentState.instantiate and cleared in onCreate.
      FragmentManagerNonConfig mChildNonConfig;
  
      // If this Fragment is contained in another Fragment, this is that container.
      Fragment mParentFragment;
  
      // The optional identifier for this fragment -- either the container ID if it
      // was dynamically added to the view hierarchy, or the ID supplied in
      // layout.
      @UnsupportedAppUsage
      int mFragmentId;
  
      // When a fragment is being dynamically added to the view hierarchy, this
      // is the identifier of the parent container it is being added to.
      int mContainerId;
  
      // The optional named tag for this fragment -- usually used to find
      // fragments that are not part of the layout.
      String mTag;
  
      // Set to true when the app has requested that this fragment be hidden
      // from the user.
      boolean mHidden;
  
      // Set to true when the app has requested that this fragment be detached.
      boolean mDetached;
  
      // If set this fragment would like its instance retained across
      // configuration changes.
      boolean mRetainInstance;
  
      // If set this fragment is being retained across the current config change.
      boolean mRetaining;
  
      // If set this fragment has menu items to contribute.
      boolean mHasMenu;
  
      // Set to true to allow the fragment's menu to be shown.
      boolean mMenuVisible = true;
  
      // Used to verify that subclasses call through to super class.
      boolean mCalled;
  
      // The parent container of the fragment after dynamically added to UI.
      ViewGroup mContainer;
  
      // The View generated for this fragment.
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
      View mView;
  
      // Whether this fragment should defer starting until after other fragments
      // have been started and their loaders are finished.
      boolean mDeferStart;
  
      // Hint provided by the app that this fragment is currently visible to the user.
      boolean mUserVisibleHint = true;
  
      LoaderManagerImpl mLoaderManager;
      @UnsupportedAppUsage
      boolean mLoadersStarted;
      boolean mCheckedForLoaderManager;
  
      // The animation and transition information for the fragment. This will be null
      // unless the elements are explicitly accessed and should remain null for Fragments
      // without Views.
      AnimationInfo mAnimationInfo;
  
      // True if the View was added, and its animation has yet to be run. This could
      // also indicate that the fragment view hasn't been made visible, even if there is no
      // animation for this fragment.
      boolean mIsNewlyAdded;
  
      // True if mHidden has been changed and the animation should be scheduled.
      boolean mHiddenChanged;
  
      // The cached value from onGetLayoutInflater(Bundle) that will be returned from
      // getLayoutInflater()
      LayoutInflater mLayoutInflater;
  
      // Keep track of whether or not this Fragment has run performCreate(). Retained instance
      // fragments can have mRetaining set to true without going through creation, so we must
      // track it separately.
      boolean mIsCreated;
  
      /**
       * State information that has been retrieved from a fragment instance
       * through {@link FragmentManager#saveFragmentInstanceState(Fragment)
       * FragmentManager.saveFragmentInstanceState}.
       *
       * @deprecated Use {@link android.support.v4.app.Fragment.SavedState}
       */
      @Deprecated
      public static class SavedState implements Parcelable {
          final Bundle mState;
  
          SavedState(Bundle state) {
              mState = state;
          }
  
          SavedState(Parcel in, ClassLoader loader) {
              mState = in.readBundle();
              if (loader != null && mState != null) {
                  mState.setClassLoader(loader);
              }
          }
  
          @Override
          public int describeContents() {
              return 0;
          }
  
          @Override
          public void writeToParcel(Parcel dest, int flags) {
              dest.writeBundle(mState);
          }
  
          public static final Parcelable.ClassLoaderCreator<SavedState> CREATOR
                  = new Parcelable.ClassLoaderCreator<SavedState>() {
              public SavedState createFromParcel(Parcel in) {
                  return new SavedState(in, null);
              }
  
              public SavedState createFromParcel(Parcel in, ClassLoader loader) {
                  return new SavedState(in, loader);
              }
  
              public SavedState[] newArray(int size) {
                  return new SavedState[size];
              }
          };
      }
  
      /**
       * Thrown by {@link Fragment#instantiate(Context, String, Bundle)} when
       * there is an instantiation failure.
       *
       * @deprecated Use {@link android.support.v4.app.Fragment.InstantiationException}
       */
      @Deprecated
      static public class InstantiationException extends AndroidRuntimeException {
          public InstantiationException(String msg, Exception cause) {
              super(msg, cause);
          }
      }
  
      /**
       * Default constructor.  <strong>Every</strong> fragment must have an
       * empty constructor, so it can be instantiated when restoring its
       * activity's state.  It is strongly recommended that subclasses do not
       * have other constructors with parameters, since these constructors
       * will not be called when the fragment is re-instantiated; instead,
       * arguments can be supplied by the caller with {@link #setArguments}
       * and later retrieved by the Fragment with {@link #getArguments}.
       *
       * <p>Applications should generally not implement a constructor. Prefer
       * {@link #onAttach(Context)} instead. It is the first place application code can run where
       * the fragment is ready to be used - the point where the fragment is actually associated with
       * its context. Some applications may also want to implement {@link #onInflate} to retrieve
       * attributes from a layout resource, although note this happens when the fragment is attached.
       */
      public Fragment() {
      }
  
      /**
       * Like {@link #instantiate(Context, String, Bundle)} but with a null
       * argument Bundle.
       */
      public static Fragment instantiate(Context context, String fname) {
          return instantiate(context, fname, null);
      }
  
      /**
       * Create a new instance of a Fragment with the given class name.  This is
       * the same as calling its empty constructor.
       *
       * @param context The calling context being used to instantiate the fragment.
       * This is currently just used to get its ClassLoader.
       * @param fname The class name of the fragment to instantiate.
       * @param args Bundle of arguments to supply to the fragment, which it
       * can retrieve with {@link #getArguments()}.  May be null.
       * @return Returns a new fragment instance.
       * @throws InstantiationException If there is a failure in instantiating
       * the given fragment class.  This is a runtime exception; it is not
       * normally expected to happen.
       */
      public static Fragment instantiate(Context context, String fname, @Nullable Bundle args) {
          try {
              Class<?> clazz = sClassMap.get(fname);
              if (clazz == null) {
                  // Class not found in the cache, see if it's real, and try to add it
                  clazz = context.getClassLoader().loadClass(fname);
                  if (!Fragment.class.isAssignableFrom(clazz)) {
                      throw new InstantiationException("Trying to instantiate a class " + fname
                              + " that is not a Fragment", new ClassCastException());
                  }
                  sClassMap.put(fname, clazz);
              }
              Fragment f = (Fragment) clazz.getConstructor().newInstance();
              if (args != null) {
                  args.setClassLoader(f.getClass().getClassLoader());
                  f.setArguments(args);
              }
              return f;
          } catch (ClassNotFoundException e) {
              throw new InstantiationException("Unable to instantiate fragment " + fname
                      + ": make sure class name exists, is public, and has an"
                      + " empty constructor that is public", e);
          } catch (java.lang.InstantiationException e) {
              throw new InstantiationException("Unable to instantiate fragment " + fname
                      + ": make sure class name exists, is public, and has an"
                      + " empty constructor that is public", e);
          } catch (IllegalAccessException e) {
              throw new InstantiationException("Unable to instantiate fragment " + fname
                      + ": make sure class name exists, is public, and has an"
                      + " empty constructor that is public", e);
          } catch (NoSuchMethodException e) {
              throw new InstantiationException("Unable to instantiate fragment " + fname
                      + ": could not find Fragment constructor", e);
          } catch (InvocationTargetException e) {
              throw new InstantiationException("Unable to instantiate fragment " + fname
                      + ": calling Fragment constructor caused an exception", e);
          }
      }
  
      final void restoreViewState(Bundle savedInstanceState) {
          if (mSavedViewState != null) {
              mView.restoreHierarchyState(mSavedViewState);
              mSavedViewState = null;
          }
          mCalled = false;
          onViewStateRestored(savedInstanceState);
          if (!mCalled) {
              throw new SuperNotCalledException("Fragment " + this
                      + " did not call through to super.onViewStateRestored()");
          }
      }
  
      final void setIndex(int index, Fragment parent) {
          mIndex = index;
          if (parent != null) {
              mWho = parent.mWho + ":" + mIndex;
          } else {
              mWho = "android:fragment:" + mIndex;
          }
      }
  
      final boolean isInBackStack() {
          return mBackStackNesting > 0;
      }
  
      /**
       * Subclasses can not override equals().
       */
      @Override final public boolean equals(Object o) {
          return super.equals(o);
      }
  
      /**
       * Subclasses can not override hashCode().
       */
      @Override final public int hashCode() {
          return super.hashCode();
      }
  
      @Override
      public String toString() {
          StringBuilder sb = new StringBuilder(128);
          DebugUtils.buildShortClassTag(this, sb);
          if (mIndex >= 0) {
              sb.append(" #");
              sb.append(mIndex);
          }
          if (mFragmentId != 0) {
              sb.append(" id=0x");
              sb.append(Integer.toHexString(mFragmentId));
          }
          if (mTag != null) {
              sb.append(" ");
              sb.append(mTag);
          }
          sb.append('}');
          return sb.toString();
      }
  
      /**
       * Return the identifier this fragment is known by.  This is either
       * the android:id value supplied in a layout or the container view ID
       * supplied when adding the fragment.
       */
      final public int getId() {
          return mFragmentId;
      }
  
      /**
       * Get the tag name of the fragment, if specified.
       */
      final public String getTag() {
          return mTag;
      }
  
      /**
       * Supply the construction arguments for this fragment.
       * The arguments supplied here will be retained across fragment destroy and
       * creation.
       *
       * <p>This method cannot be called if the fragment is added to a FragmentManager and
       * if {@link #isStateSaved()} would return true. Prior to {@link Build.VERSION_CODES#O},
       * this method may only be called if the fragment has not yet been added to a FragmentManager.
       * </p>
       */
      public void setArguments(Bundle args) {
          // The isStateSaved requirement below was only added in Android O and is compatible
          // because it loosens previous requirements rather than making them more strict.
          // See method javadoc.
          if (mIndex >= 0 && isStateSaved()) {
              throw new IllegalStateException("Fragment already active");
          }
          mArguments = args;
      }
  
      /**
       * Return the arguments supplied to {@link #setArguments}, if any.
       */
      final public Bundle getArguments() {
          return mArguments;
      }
  
      /**
       * Returns true if this fragment is added and its state has already been saved
       * by its host. Any operations that would change saved state should not be performed
       * if this method returns true, and some operations such as {@link #setArguments(Bundle)}
       * will fail.
       *
       * @return true if this fragment's state has already been saved by its host
       */
      public final boolean isStateSaved() {
          if (mFragmentManager == null) {
              return false;
          }
          return mFragmentManager.isStateSaved();
      }
  
      /**
       * Set the initial saved state that this Fragment should restore itself
       * from when first being constructed, as returned by
       * {@link FragmentManager#saveFragmentInstanceState(Fragment)
       * FragmentManager.saveFragmentInstanceState}.
       *
       * @param state The state the fragment should be restored from.
       */
      public void setInitialSavedState(SavedState state) {
          if (mIndex >= 0) {
              throw new IllegalStateException("Fragment already active");
          }
          mSavedFragmentState = state != null && state.mState != null
                  ? state.mState : null;
      }
  
      /**
       * Optional target for this fragment.  This may be used, for example,
       * if this fragment is being started by another, and when done wants to
       * give a result back to the first.  The target set here is retained
       * across instances via {@link FragmentManager#putFragment
       * FragmentManager.putFragment()}.
       *
       * @param fragment The fragment that is the target of this one.
       * @param requestCode Optional request code, for convenience if you
       * are going to call back with {@link #onActivityResult(int, int, Intent)}.
       */
      public void setTargetFragment(Fragment fragment, int requestCode) {
          // Don't allow a caller to set a target fragment in another FragmentManager,
          // but there's a snag: people do set target fragments before fragments get added.
          // We'll have the FragmentManager check that for validity when we move
          // the fragments to a valid state.
          final FragmentManager mine = getFragmentManager();
          final FragmentManager theirs = fragment != null ? fragment.getFragmentManager() : null;
          if (mine != null && theirs != null && mine != theirs) {
              throw new IllegalArgumentException("Fragment " + fragment
                      + " must share the same FragmentManager to be set as a target fragment");
          }
  
          // Don't let someone create a cycle.
          for (Fragment check = fragment; check != null; check = check.getTargetFragment()) {
              if (check == this) {
                  throw new IllegalArgumentException("Setting " + fragment + " as the target of "
                          + this + " would create a target cycle");
              }
          }
          mTarget = fragment;
          mTargetRequestCode = requestCode;
      }
  
      /**
       * Return the target fragment set by {@link #setTargetFragment}.
       */
      final public Fragment getTargetFragment() {
          return mTarget;
      }
  
      /**
       * Return the target request code set by {@link #setTargetFragment}.
       */
      final public int getTargetRequestCode() {
          return mTargetRequestCode;
      }
  
      /**
       * Return the {@link Context} this fragment is currently associated with.
       */
      public Context getContext() {
          return mHost == null ? null : mHost.getContext();
      }
  
      /**
       * Return the Activity this fragment is currently associated with.
       */
      final public Activity getActivity() {
          return mHost == null ? null : mHost.getActivity();
      }
  
      /**
       * Return the host object of this fragment. May return {@code null} if the fragment
       * isn't currently being hosted.
       */
      @Nullable
      final public Object getHost() {
          return mHost == null ? null : mHost.onGetHost();
      }
  
      /**
       * Return <code>getActivity().getResources()</code>.
       */
      final public Resources getResources() {
          if (mHost == null) {
              throw new IllegalStateException("Fragment " + this + " not attached to Activity");
          }
          return mHost.getContext().getResources();
      }
  
      /**
       * Return a localized, styled CharSequence from the application's package's
       * default string table.
       *
       * @param resId Resource id for the CharSequence text
       */
      public final CharSequence getText(@StringRes int resId) {
          return getResources().getText(resId);
      }
  
      /**
       * Return a localized string from the application's package's
       * default string table.
       *
       * @param resId Resource id for the string
       */
      public final String getString(@StringRes int resId) {
          return getResources().getString(resId);
      }
  
      /**
       * Return a localized formatted string from the application's package's
       * default string table, substituting the format arguments as defined in
       * {@link java.util.Formatter} and {@link java.lang.String#format}.
       *
       * @param resId Resource id for the format string
       * @param formatArgs The format arguments that will be used for substitution.
       */
  
      public final String getString(@StringRes int resId, Object... formatArgs) {
          return getResources().getString(resId, formatArgs);
      }
  
      /**
       * Return the FragmentManager for interacting with fragments associated
       * with this fragment's activity.  Note that this will be non-null slightly
       * before {@link #getActivity()}, during the time from when the fragment is
       * placed in a {@link FragmentTransaction} until it is committed and
       * attached to its activity.
       *
       * <p>If this Fragment is a child of another Fragment, the FragmentManager
       * returned here will be the parent's {@link #getChildFragmentManager()}.
       */
      final public FragmentManager getFragmentManager() {
          return mFragmentManager;
      }
  
      /**
       * Return a private FragmentManager for placing and managing Fragments
       * inside of this Fragment.
       */
      final public FragmentManager getChildFragmentManager() {
          if (mChildFragmentManager == null) {
              instantiateChildFragmentManager();
              if (mState >= RESUMED) {
                  mChildFragmentManager.dispatchResume();
              } else if (mState >= STARTED) {
                  mChildFragmentManager.dispatchStart();
              } else if (mState >= ACTIVITY_CREATED) {
                  mChildFragmentManager.dispatchActivityCreated();
              } else if (mState >= CREATED) {
                  mChildFragmentManager.dispatchCreate();
              }
          }
          return mChildFragmentManager;
      }
  
      /**
       * Returns the parent Fragment containing this Fragment.  If this Fragment
       * is attached directly to an Activity, returns null.
       */
      final public Fragment getParentFragment() {
          return mParentFragment;
      }
  
      /**
       * Return true if the fragment is currently added to its activity.
       */
      final public boolean isAdded() {
          return mHost != null && mAdded;
      }
  
      /**
       * Return true if the fragment has been explicitly detached from the UI.
       * That is, {@link FragmentTransaction#detach(Fragment)
       * FragmentTransaction.detach(Fragment)} has been used on it.
       */
      final public boolean isDetached() {
          return mDetached;
      }
  
      /**
       * Return true if this fragment is currently being removed from its
       * activity.  This is  <em>not</em> whether its activity is finishing, but
       * rather whether it is in the process of being removed from its activity.
       */
      final public boolean isRemoving() {
          return mRemoving;
      }
  
      /**
       * Return true if the layout is included as part of an activity view
       * hierarchy via the &lt;fragment&gt; tag.  This will always be true when
       * fragments are created through the &lt;fragment&gt; tag, <em>except</em>
       * in the case where an old fragment is restored from a previous state and
       * it does not appear in the layout of the current state.
       */
      final public boolean isInLayout() {
          return mInLayout;
      }
  
      /**
       * Return true if the fragment is in the resumed state.  This is true
       * for the duration of {@link #onResume()} and {@link #onPause()} as well.
       */
      final public boolean isResumed() {
          return mState >= RESUMED;
      }
  
      /**
       * Return true if the fragment is currently visible to the user.  This means
       * it: (1) has been added, (2) has its view attached to the window, and
       * (3) is not hidden.
       */
      final public boolean isVisible() {
          return isAdded() && !isHidden() && mView != null
                  && mView.getWindowToken() != null && mView.getVisibility() == View.VISIBLE;
      }
  
      /**
       * Return true if the fragment has been hidden.  By default fragments
       * are shown.  You can find out about changes to this state with
       * {@link #onHiddenChanged}.  Note that the hidden state is orthogonal
       * to other states -- that is, to be visible to the user, a fragment
       * must be both started and not hidden.
       */
      final public boolean isHidden() {
          return mHidden;
      }
  
      /**
       * Called when the hidden state (as returned by {@link #isHidden()} of
       * the fragment has changed.  Fragments start out not hidden; this will
       * be called whenever the fragment changes state from that.
       * @param hidden True if the fragment is now hidden, false otherwise.
       */
      public void onHiddenChanged(boolean hidden) {
      }
  
      /**
       * Control whether a fragment instance is retained across Activity
       * re-creation (such as from a configuration change).  This can only
       * be used with fragments not in the back stack.  If set, the fragment
       * lifecycle will be slightly different when an activity is recreated:
       * <ul>
       * <li> {@link #onDestroy()} will not be called (but {@link #onDetach()} still
       * will be, because the fragment is being detached from its current activity).
       * <li> {@link #onCreate(Bundle)} will not be called since the fragment
       * is not being re-created.
       * <li> {@link #onAttach(Activity)} and {@link #onActivityCreated(Bundle)} <b>will</b>
       * still be called.
       * </ul>
       */
      public void setRetainInstance(boolean retain) {
          mRetainInstance = retain;
      }
  
      final public boolean getRetainInstance() {
          return mRetainInstance;
      }
  
      /**
       * Report that this fragment would like to participate in populating
       * the options menu by receiving a call to {@link #onCreateOptionsMenu}
       * and related methods.
       *
       * @param hasMenu If true, the fragment has menu items to contribute.
       */
      public void setHasOptionsMenu(boolean hasMenu) {
          if (mHasMenu != hasMenu) {
              mHasMenu = hasMenu;
              if (isAdded() && !isHidden()) {
                  mFragmentManager.invalidateOptionsMenu();
              }
          }
      }
  
      /**
       * Set a hint for whether this fragment's menu should be visible.  This
       * is useful if you know that a fragment has been placed in your view
       * hierarchy so that the user can not currently seen it, so any menu items
       * it has should also not be shown.
       *
       * @param menuVisible The default is true, meaning the fragment's menu will
       * be shown as usual.  If false, the user will not see the menu.
       */
      public void setMenuVisibility(boolean menuVisible) {
          if (mMenuVisible != menuVisible) {
              mMenuVisible = menuVisible;
              if (mHasMenu && isAdded() && !isHidden()) {
                  mFragmentManager.invalidateOptionsMenu();
              }
          }
      }
  
      /**
       * Set a hint to the system about whether this fragment's UI is currently visible
       * to the user. This hint defaults to true and is persistent across fragment instance
       * state save and restore.
       *
       * <p>An app may set this to false to indicate that the fragment's UI is
       * scrolled out of visibility or is otherwise not directly visible to the user.
       * This may be used by the system to prioritize operations such as fragment lifecycle updates
       * or loader ordering behavior.</p>
       *
       * <p><strong>Note:</strong> This method may be called outside of the fragment lifecycle
       * and thus has no ordering guarantees with regard to fragment lifecycle method calls.</p>
       *
       * <p><strong>Note:</strong> Prior to Android N there was a platform bug that could cause
       * <code>setUserVisibleHint</code> to bring a fragment up to the started state before its
       * <code>FragmentTransaction</code> had been committed. As some apps relied on this behavior,
       * it is preserved for apps that declare a <code>targetSdkVersion</code> of 23 or lower.</p>
       *
       * @param isVisibleToUser true if this fragment's UI is currently visible to the user (default),
       *                        false if it is not.
       */
      public void setUserVisibleHint(boolean isVisibleToUser) {
          // Prior to Android N we were simply checking if this fragment had a FragmentManager
          // set before we would trigger a deferred start. Unfortunately this also gets set before
          // a fragment transaction is committed, so if setUserVisibleHint was called before a
          // transaction commit, we would start the fragment way too early. FragmentPagerAdapter
          // triggers this situation.
          // Unfortunately some apps relied on this timing in overrides of setUserVisibleHint
          // on their own fragments, and expected, however erroneously, that after a call to
          // super.setUserVisibleHint their onStart methods had been run.
          // We preserve this behavior for apps targeting old platform versions below.
          boolean useBrokenAddedCheck = false;
          Context context = getContext();
          if (mFragmentManager != null && mFragmentManager.mHost != null) {
              context = mFragmentManager.mHost.getContext();
          }
          if (context != null) {
              useBrokenAddedCheck = context.getApplicationInfo().targetSdkVersion <= VERSION_CODES.M;
          }
  
          final boolean performDeferredStart;
          if (useBrokenAddedCheck) {
              performDeferredStart = !mUserVisibleHint && isVisibleToUser && mState < STARTED
                      && mFragmentManager != null;
          } else {
              performDeferredStart = !mUserVisibleHint && isVisibleToUser && mState < STARTED
                      && mFragmentManager != null && isAdded();
          }
  
          if (performDeferredStart) {
              mFragmentManager.performPendingDeferredStart(this);
          }
  
          mUserVisibleHint = isVisibleToUser;
          mDeferStart = mState < STARTED && !isVisibleToUser;
      }
  
      /**
       * @return The current value of the user-visible hint on this fragment.
       * @see #setUserVisibleHint(boolean)
       */
      public boolean getUserVisibleHint() {
          return mUserVisibleHint;
      }
  
      /**
       * Return the LoaderManager for this fragment, creating it if needed.
       *
       * @deprecated Use {@link android.support.v4.app.Fragment#getLoaderManager()}
       */
      @Deprecated
      public LoaderManager getLoaderManager() {
          if (mLoaderManager != null) {
              return mLoaderManager;
          }
          if (mHost == null) {
              throw new IllegalStateException("Fragment " + this + " not attached to Activity");
          }
          mCheckedForLoaderManager = true;
          mLoaderManager = mHost.getLoaderManager(mWho, mLoadersStarted, true);
          return mLoaderManager;
      }
  
      /**
       * Call {@link Activity#startActivity(Intent)} from the fragment's
       * containing Activity.
       *
       * @param intent The intent to start.
       */
      public void startActivity(Intent intent) {
          startActivity(intent, null);
      }
  
      /**
       * Call {@link Activity#startActivity(Intent, Bundle)} from the fragment's
       * containing Activity.
       *
       * @param intent The intent to start.
       * @param options Additional options for how the Activity should be started.
       * See {@link android.content.Context#startActivity(Intent, Bundle)}
       * Context.startActivity(Intent, Bundle)} for more details.
       */
      public void startActivity(Intent intent, Bundle options) {
          if (mHost == null) {
              throw new IllegalStateException("Fragment " + this + " not attached to Activity");
          }
          if (options != null) {
              mHost.onStartActivityFromFragment(this, intent, -1, options);
          } else {
              // Note we want to go through this call for compatibility with
              // applications that may have overridden the method.
              mHost.onStartActivityFromFragment(this, intent, -1, null /*options*/);
          }
      }
  
      /**
       * Call {@link Activity#startActivityForResult(Intent, int)} from the fragment's
       * containing Activity.
       */
      public void startActivityForResult(Intent intent, int requestCode) {
          startActivityForResult(intent, requestCode, null);
      }
  
      /**
       * Call {@link Activity#startActivityForResult(Intent, int, Bundle)} from the fragment's
       * containing Activity.
       */
      public void startActivityForResult(Intent intent, int requestCode, Bundle options) {
          if (mHost == null) {
              throw new IllegalStateException("Fragment " + this + " not attached to Activity");
          }
          mHost.onStartActivityFromFragment(this, intent, requestCode, options);
      }
  
      /**
       * @hide
       * Call {@link Activity#startActivityForResultAsUser(Intent, int, UserHandle)} from the
       * fragment's containing Activity.
       */
      public void startActivityForResultAsUser(
              Intent intent, int requestCode, Bundle options, UserHandle user) {
          if (mHost == null) {
              throw new IllegalStateException("Fragment " + this + " not attached to Activity");
          }
          mHost.onStartActivityAsUserFromFragment(this, intent, requestCode, options, user);
      }
  
      /**
       * Call {@link Activity#startIntentSenderForResult(IntentSender, int, Intent, int, int, int,
       * Bundle)} from the fragment's containing Activity.
       */
      public void startIntentSenderForResult(IntentSender intent, int requestCode,
              @Nullable Intent fillInIntent, int flagsMask, int flagsValues, int extraFlags,
              Bundle options) throws IntentSender.SendIntentException {
          if (mHost == null) {
              throw new IllegalStateException("Fragment " + this + " not attached to Activity");
          }
          mHost.onStartIntentSenderFromFragment(this, intent, requestCode, fillInIntent, flagsMask,
                  flagsValues, extraFlags, options);
      }
  
      /**
       * Receive the result from a previous call to
       * {@link #startActivityForResult(Intent, int)}.  This follows the
       * related Activity API as described there in
       * {@link Activity#onActivityResult(int, int, Intent)}.
       *
       * @param requestCode The integer request code originally supplied to
       *                    startActivityForResult(), allowing you to identify who this
       *                    result came from.
       * @param resultCode The integer result code returned by the child activity
       *                   through its setResult().
       * @param data An Intent, which can return result data to the caller
       *               (various data can be attached to Intent "extras").
       */
      public void onActivityResult(int requestCode, int resultCode, Intent data) {
      }
  
      /**
       * Requests permissions to be granted to this application. These permissions
       * must be requested in your manifest, they should not be granted to your app,
       * and they should have protection level {@link android.content.pm.PermissionInfo
       * #PROTECTION_DANGEROUS dangerous}, regardless whether they are declared by
       * the platform or a third-party app.
       * <p>
       * Normal permissions {@link android.content.pm.PermissionInfo#PROTECTION_NORMAL}
       * are granted at install time if requested in the manifest. Signature permissions
       * {@link android.content.pm.PermissionInfo#PROTECTION_SIGNATURE} are granted at
       * install time if requested in the manifest and the signature of your app matches
       * the signature of the app declaring the permissions.
       * </p>
       * <p>
       * If your app does not have the requested permissions the user will be presented
       * with UI for accepting them. After the user has accepted or rejected the
       * requested permissions you will receive a callback on {@link
       * #onRequestPermissionsResult(int, String[], int[])} reporting whether the
       * permissions were granted or not.
       * </p>
       * <p>
       * Note that requesting a permission does not guarantee it will be granted and
       * your app should be able to run without having this permission.
       * </p>
       * <p>
       * This method may start an activity allowing the user to choose which permissions
       * to grant and which to reject. Hence, you should be prepared that your activity
       * may be paused and resumed. Further, granting some permissions may require
       * a restart of you application. In such a case, the system will recreate the
       * activity stack before delivering the result to {@link
       * #onRequestPermissionsResult(int, String[], int[])}.
       * </p>
       * <p>
       * When checking whether you have a permission you should use {@link
       * android.content.Context#checkSelfPermission(String)}.
       * </p>
       * <p>
       * Calling this API for permissions already granted to your app would show UI
       * to the user to decide whether the app can still hold these permissions. This
       * can be useful if the way your app uses data guarded by the permissions
       * changes significantly.
       * </p>
       * <p>
       * You cannot request a permission if your activity sets {@link
       * android.R.styleable#AndroidManifestActivity_noHistory noHistory} to
       * <code>true</code> because in this case the activity would not receive
       * result callbacks including {@link #onRequestPermissionsResult(int, String[], int[])}.
       * </p>
       * <p>
       * A sample permissions request looks like this:
       * </p>
       * <code><pre><p>
       * private void showContacts() {
       *     if (getActivity().checkSelfPermission(Manifest.permission.READ_CONTACTS)
       *             != PackageManager.PERMISSION_GRANTED) {
       *         requestPermissions(new String[]{Manifest.permission.READ_CONTACTS},
       *                 PERMISSIONS_REQUEST_READ_CONTACTS);
       *     } else {
       *         doShowContacts();
       *     }
       * }
       *
       * {@literal @}Override
       * public void onRequestPermissionsResult(int requestCode, String[] permissions,
       *         int[] grantResults) {
       *     if (requestCode == PERMISSIONS_REQUEST_READ_CONTACTS
       *             && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
       *         doShowContacts();
       *     }
       * }
       * </code></pre></p>
       *
       * @param permissions The requested permissions. Must me non-null and not empty.
       * @param requestCode Application specific request code to match with a result
       *    reported to {@link #onRequestPermissionsResult(int, String[], int[])}.
       *    Should be >= 0.
       *
       * @see #onRequestPermissionsResult(int, String[], int[])
       * @see android.content.Context#checkSelfPermission(String)
       */
      public final void requestPermissions(@NonNull String[] permissions, int requestCode) {
          if (mHost == null) {
              throw new IllegalStateException("Fragment " + this + " not attached to Activity");
          }
          mHost.onRequestPermissionsFromFragment(this, permissions,requestCode);
      }
  
      /**
       * Callback for the result from requesting permissions. This method
       * is invoked for every call on {@link #requestPermissions(String[], int)}.
       * <p>
       * <strong>Note:</strong> It is possible that the permissions request interaction
       * with the user is interrupted. In this case you will receive empty permissions
       * and results arrays which should be treated as a cancellation.
       * </p>
       *
       * @param requestCode The request code passed in {@link #requestPermissions(String[], int)}.
       * @param permissions The requested permissions. Never null.
       * @param grantResults The grant results for the corresponding permissions
       *     which is either {@link android.content.pm.PackageManager#PERMISSION_GRANTED}
       *     or {@link android.content.pm.PackageManager#PERMISSION_DENIED}. Never null.
       *
       * @see #requestPermissions(String[], int)
       */
      public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
              @NonNull int[] grantResults) {
          /* callback - do nothing */
      }
  
      /**
       * Gets whether you should show UI with rationale for requesting a permission.
       * You should do this only if you do not have the permission and the context in
       * which the permission is requested does not clearly communicate to the user
       * what would be the benefit from granting this permission.
       * <p>
       * For example, if you write a camera app, requesting the camera permission
       * would be expected by the user and no rationale for why it is requested is
       * needed. If however, the app needs location for tagging photos then a non-tech
       * savvy user may wonder how location is related to taking photos. In this case
       * you may choose to show UI with rationale of requesting this permission.
       * </p>
       *
       * @param permission A permission your app wants to request.
       * @return Whether you can show permission rationale UI.
       *
       * @see Context#checkSelfPermission(String)
       * @see #requestPermissions(String[], int)
       * @see #onRequestPermissionsResult(int, String[], int[])
       */
      public boolean shouldShowRequestPermissionRationale(@NonNull String permission) {
          if (mHost != null) {
              return mHost.getContext().getPackageManager()
                      .shouldShowRequestPermissionRationale(permission);
          }
          return false;
      }
  
      /**
       * Returns the LayoutInflater used to inflate Views of this Fragment. The default
       * implementation will throw an exception if the Fragment is not attached.
       *
       * @return The LayoutInflater used to inflate Views of this Fragment.
       */
      public LayoutInflater onGetLayoutInflater(Bundle savedInstanceState) {
          if (mHost == null) {
              throw new IllegalStateException("onGetLayoutInflater() cannot be executed until the "
                      + "Fragment is attached to the FragmentManager.");
          }
          final LayoutInflater result = mHost.onGetLayoutInflater();
          if (mHost.onUseFragmentManagerInflaterFactory()) {
              getChildFragmentManager(); // Init if needed; use raw implementation below.
              result.setPrivateFactory(mChildFragmentManager.getLayoutInflaterFactory());
          }
          return result;
      }
  
      /**
       * Returns the cached LayoutInflater used to inflate Views of this Fragment. If
       * {@link #onGetLayoutInflater(Bundle)} has not been called {@link #onGetLayoutInflater(Bundle)}
       * will be called with a {@code null} argument and that value will be cached.
       * <p>
       * The cached LayoutInflater will be replaced immediately prior to
       * {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)} and cleared immediately after
       * {@link #onDetach()}.
       *
       * @return The LayoutInflater used to inflate Views of this Fragment.
       */
      public final LayoutInflater getLayoutInflater() {
          if (mLayoutInflater == null) {
              return performGetLayoutInflater(null);
          }
          return mLayoutInflater;
      }
  
      /**
       * Calls {@link #onGetLayoutInflater(Bundle)} and caches the result for use by
       * {@link #getLayoutInflater()}.
       *
       * @param savedInstanceState If the fragment is being re-created from
       * a previous saved state, this is the state.
       * @return The LayoutInflater used to inflate Views of this Fragment.
       */
      LayoutInflater performGetLayoutInflater(Bundle savedInstanceState) {
          LayoutInflater layoutInflater = onGetLayoutInflater(savedInstanceState);
          mLayoutInflater = layoutInflater;
          return mLayoutInflater;
      }
  
      /**
       * @deprecated Use {@link #onInflate(Context, AttributeSet, Bundle)} instead.
       */
      @Deprecated
      @CallSuper
      public void onInflate(AttributeSet attrs, Bundle savedInstanceState) {
          mCalled = true;
      }
  
      /**
       * Called when a fragment is being created as part of a view layout
       * inflation, typically from setting the content view of an activity.  This
       * may be called immediately after the fragment is created from a <fragment>
       * tag in a layout file.  Note this is <em>before</em> the fragment's
       * {@link #onAttach(Activity)} has been called; all you should do here is
       * parse the attributes and save them away.
       *
       * <p>This is called every time the fragment is inflated, even if it is
       * being inflated into a new instance with saved state.  It typically makes
       * sense to re-parse the parameters each time, to allow them to change with
       * different configurations.</p>
       *
       * <p>Here is a typical implementation of a fragment that can take parameters
       * both through attributes supplied here as well from {@link #getArguments()}:</p>
       *
       * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentArguments.java
       *      fragment}
       *
       * <p>Note that parsing the XML attributes uses a "styleable" resource.  The
       * declaration for the styleable used here is:</p>
       *
       * {@sample development/samples/ApiDemos/res/values/attrs.xml fragment_arguments}
       *
       * <p>The fragment can then be declared within its activity's content layout
       * through a tag like this:</p>
       *
       * {@sample development/samples/ApiDemos/res/layout/fragment_arguments.xml from_attributes}
       *
       * <p>This fragment can also be created dynamically from arguments given
       * at runtime in the arguments Bundle; here is an example of doing so at
       * creation of the containing activity:</p>
       *
       * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentArguments.java
       *      create}
       *
       * @param context The Context that is inflating this fragment.
       * @param attrs The attributes at the tag where the fragment is
       * being created.
       * @param savedInstanceState If the fragment is being re-created from
       * a previous saved state, this is the state.
       */
      @CallSuper
      public void onInflate(Context context, AttributeSet attrs, Bundle savedInstanceState) {
          onInflate(attrs, savedInstanceState);
          mCalled = true;
  
          TypedArray a = context.obtainStyledAttributes(attrs,
                  com.android.internal.R.styleable.Fragment);
          setEnterTransition(loadTransition(context, a, getEnterTransition(), null,
                  com.android.internal.R.styleable.Fragment_fragmentEnterTransition));
          setReturnTransition(loadTransition(context, a, getReturnTransition(),
                  USE_DEFAULT_TRANSITION,
                  com.android.internal.R.styleable.Fragment_fragmentReturnTransition));
          setExitTransition(loadTransition(context, a, getExitTransition(), null,
                  com.android.internal.R.styleable.Fragment_fragmentExitTransition));
  
          setReenterTransition(loadTransition(context, a, getReenterTransition(),
                  USE_DEFAULT_TRANSITION,
                  com.android.internal.R.styleable.Fragment_fragmentReenterTransition));
          setSharedElementEnterTransition(loadTransition(context, a,
                  getSharedElementEnterTransition(), null,
                  com.android.internal.R.styleable.Fragment_fragmentSharedElementEnterTransition));
          setSharedElementReturnTransition(loadTransition(context, a,
                  getSharedElementReturnTransition(), USE_DEFAULT_TRANSITION,
                  com.android.internal.R.styleable.Fragment_fragmentSharedElementReturnTransition));
          boolean isEnterSet;
          boolean isReturnSet;
          if (mAnimationInfo == null) {
              isEnterSet = false;
              isReturnSet = false;
          } else {
              isEnterSet = mAnimationInfo.mAllowEnterTransitionOverlap != null;
              isReturnSet = mAnimationInfo.mAllowReturnTransitionOverlap != null;
          }
          if (!isEnterSet) {
              setAllowEnterTransitionOverlap(a.getBoolean(
                      com.android.internal.R.styleable.Fragment_fragmentAllowEnterTransitionOverlap,
                      true));
          }
          if (!isReturnSet) {
              setAllowReturnTransitionOverlap(a.getBoolean(
                      com.android.internal.R.styleable.Fragment_fragmentAllowReturnTransitionOverlap,
                      true));
          }
          a.recycle();
  
          final Activity hostActivity = mHost == null ? null : mHost.getActivity();
          if (hostActivity != null) {
              mCalled = false;
              onInflate(hostActivity, attrs, savedInstanceState);
          }
      }
  
      /**
       * @deprecated Use {@link #onInflate(Context, AttributeSet, Bundle)} instead.
       */
      @Deprecated
      @CallSuper
      public void onInflate(Activity activity, AttributeSet attrs, Bundle savedInstanceState) {
          mCalled = true;
      }
  
      /**
       * Called when a fragment is attached as a child of this fragment.
       *
       * <p>This is called after the attached fragment's <code>onAttach</code> and before
       * the attached fragment's <code>onCreate</code> if the fragment has not yet had a previous
       * call to <code>onCreate</code>.</p>
       *
       * @param childFragment child fragment being attached
       */
      public void onAttachFragment(Fragment childFragment) {
      }
  
      /**
       * Called when a fragment is first attached to its context.
       * {@link #onCreate(Bundle)} will be called after this.
       */
      @CallSuper
      public void onAttach(Context context) {
          mCalled = true;
          final Activity hostActivity = mHost == null ? null : mHost.getActivity();
          if (hostActivity != null) {
              mCalled = false;
              onAttach(hostActivity);
          }
      }
  
      /**
       * @deprecated Use {@link #onAttach(Context)} instead.
       */
      @Deprecated
      @CallSuper
      public void onAttach(Activity activity) {
          mCalled = true;
      }
  
      /**
       * Called when a fragment loads an animation.
       */
      public Animator onCreateAnimator(int transit, boolean enter, int nextAnim) {
          return null;
      }
  
      /**
       * Called to do initial creation of a fragment.  This is called after
       * {@link #onAttach(Activity)} and before
       * {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}, but is not called if the fragment
       * instance is retained across Activity re-creation (see {@link #setRetainInstance(boolean)}).
       *
       * <p>Note that this can be called while the fragment's activity is
       * still in the process of being created.  As such, you can not rely
       * on things like the activity's content view hierarchy being initialized
       * at this point.  If you want to do work once the activity itself is
       * created, see {@link #onActivityCreated(Bundle)}.
       *
       * <p>If your app's <code>targetSdkVersion</code> is {@link android.os.Build.VERSION_CODES#M}
       * or lower, child fragments being restored from the savedInstanceState are restored after
       * <code>onCreate</code> returns. When targeting {@link android.os.Build.VERSION_CODES#N} or
       * above and running on an N or newer platform version
       * they are restored by <code>Fragment.onCreate</code>.</p>
       *
       * @param savedInstanceState If the fragment is being re-created from
       * a previous saved state, this is the state.
       */
      @CallSuper
      public void onCreate(@Nullable Bundle savedInstanceState) {
          mCalled = true;
          final Context context = getContext();
          final int version = context != null ? context.getApplicationInfo().targetSdkVersion : 0;
          if (version >= Build.VERSION_CODES.N) {
              restoreChildFragmentState(savedInstanceState, true);
              if (mChildFragmentManager != null
                      && !mChildFragmentManager.isStateAtLeast(Fragment.CREATED)) {
                  mChildFragmentManager.dispatchCreate();
              }
          }
      }
  
      void restoreChildFragmentState(@Nullable Bundle savedInstanceState, boolean provideNonConfig) {
          if (savedInstanceState != null) {
              Parcelable p = savedInstanceState.getParcelable(Activity.FRAGMENTS_TAG);
              if (p != null) {
                  if (mChildFragmentManager == null) {
                      instantiateChildFragmentManager();
                  }
                  mChildFragmentManager.restoreAllState(p, provideNonConfig ? mChildNonConfig : null);
                  mChildNonConfig = null;
                  mChildFragmentManager.dispatchCreate();
              }
          }
      }
  
      /**
       * Called to have the fragment instantiate its user interface view.
       * This is optional, and non-graphical fragments can return null (which
       * is the default implementation).  This will be called between
       * {@link #onCreate(Bundle)} and {@link #onActivityCreated(Bundle)}.
       *
       * <p>If you return a View from here, you will later be called in
       * {@link #onDestroyView} when the view is being released.
       *
       * @param inflater The LayoutInflater object that can be used to inflate
       * any views in the fragment,
       * @param container If non-null, this is the parent view that the fragment's
       * UI should be attached to.  The fragment should not add the view itself,
       * but this can be used to generate the LayoutParams of the view.
       * @param savedInstanceState If non-null, this fragment is being re-constructed
       * from a previous saved state as given here.
       *
       * @return Return the View for the fragment's UI, or null.
       */
      @Nullable
      public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
              Bundle savedInstanceState) {
          return null;
      }
  
      /**
       * Called immediately after {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}
       * has returned, but before any saved state has been restored in to the view.
       * This gives subclasses a chance to initialize themselves once
       * they know their view hierarchy has been completely created.  The fragment's
       * view hierarchy is not however attached to its parent at this point.
       * @param view The View returned by {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}.
       * @param savedInstanceState If non-null, this fragment is being re-constructed
       * from a previous saved state as given here.
       */
      public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
      }
  
      /**
       * Get the root view for the fragment's layout (the one returned by {@link #onCreateView}),
       * if provided.
       *
       * @return The fragment's root view, or null if it has no layout.
       */
      @Nullable
      public View getView() {
          return mView;
      }
  
      /**
       * Called when the fragment's activity has been created and this
       * fragment's view hierarchy instantiated.  It can be used to do final
       * initialization once these pieces are in place, such as retrieving
       * views or restoring state.  It is also useful for fragments that use
       * {@link #setRetainInstance(boolean)} to retain their instance,
       * as this callback tells the fragment when it is fully associated with
       * the new activity instance.  This is called after {@link #onCreateView}
       * and before {@link #onViewStateRestored(Bundle)}.
       *
       * @param savedInstanceState If the fragment is being re-created from
       * a previous saved state, this is the state.
       */
      @CallSuper
      public void onActivityCreated(@Nullable Bundle savedInstanceState) {
          mCalled = true;
      }
  
      /**
       * Called when all saved state has been restored into the view hierarchy
       * of the fragment.  This can be used to do initialization based on saved
       * state that you are letting the view hierarchy track itself, such as
       * whether check box widgets are currently checked.  This is called
       * after {@link #onActivityCreated(Bundle)} and before
       * {@link #onStart()}.
       *
       * @param savedInstanceState If the fragment is being re-created from
       * a previous saved state, this is the state.
       */
      @CallSuper
      public void onViewStateRestored(Bundle savedInstanceState) {
          mCalled = true;
      }
  
      /**
       * Called when the Fragment is visible to the user.  This is generally
       * tied to {@link Activity#onStart() Activity.onStart} of the containing
       * Activity's lifecycle.
       */
      @CallSuper
      public void onStart() {
          mCalled = true;
  
          if (!mLoadersStarted) {
              mLoadersStarted = true;
              if (!mCheckedForLoaderManager) {
                  mCheckedForLoaderManager = true;
                  mLoaderManager = mHost.getLoaderManager(mWho, mLoadersStarted, false);
              } else if (mLoaderManager != null) {
                  mLoaderManager.doStart();
              }
          }
      }
  
      /**
       * Called when the fragment is visible to the user and actively running.
       * This is generally
       * tied to {@link Activity#onResume() Activity.onResume} of the containing
       * Activity's lifecycle.
       */
      @CallSuper
      public void onResume() {
          mCalled = true;
      }
  
      /**
       * Called to ask the fragment to save its current dynamic state, so it
       * can later be reconstructed in a new instance of its process is
       * restarted.  If a new instance of the fragment later needs to be
       * created, the data you place in the Bundle here will be available
       * in the Bundle given to {@link #onCreate(Bundle)},
       * {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}, and
       * {@link #onActivityCreated(Bundle)}.
       *
       * <p>This corresponds to {@link Activity#onSaveInstanceState(Bundle)
       * Activity.onSaveInstanceState(Bundle)} and most of the discussion there
       * applies here as well.  Note however: <em>this method may be called
       * at any time before {@link #onDestroy()}</em>.  There are many situations
       * where a fragment may be mostly torn down (such as when placed on the
       * back stack with no UI showing), but its state will not be saved until
       * its owning activity actually needs to save its state.
       *
       * @param outState Bundle in which to place your saved state.
       */
      public void onSaveInstanceState(Bundle outState) {
      }
  
      /**
       * Called when the Fragment's activity changes from fullscreen mode to multi-window mode and
       * visa-versa. This is generally tied to {@link Activity#onMultiWindowModeChanged} of the
       * containing Activity. This method provides the same configuration that will be sent in the
       * following {@link #onConfigurationChanged(Configuration)} call after the activity enters this
       * mode.
       *
       * @param isInMultiWindowMode True if the activity is in multi-window mode.
       * @param newConfig The new configuration of the activity with the state
       *                  {@param isInMultiWindowMode}.
       */
      public void onMultiWindowModeChanged(boolean isInMultiWindowMode, Configuration newConfig) {
          onMultiWindowModeChanged(isInMultiWindowMode);
      }
  
      /**
       * Called when the Fragment's activity changes from fullscreen mode to multi-window mode and
       * visa-versa. This is generally tied to {@link Activity#onMultiWindowModeChanged} of the
       * containing Activity.
       *
       * @param isInMultiWindowMode True if the activity is in multi-window mode.
       *
       * @deprecated Use {@link #onMultiWindowModeChanged(boolean, Configuration)} instead.
       */
      @Deprecated
      public void onMultiWindowModeChanged(boolean isInMultiWindowMode) {
      }
  
      /**
       * Called by the system when the activity changes to and from picture-in-picture mode. This is
       * generally tied to {@link Activity#onPictureInPictureModeChanged} of the containing Activity.
       * This method provides the same configuration that will be sent in the following
       * {@link #onConfigurationChanged(Configuration)} call after the activity enters this mode.
       *
       * @param isInPictureInPictureMode True if the activity is in picture-in-picture mode.
       * @param newConfig The new configuration of the activity with the state
       *                  {@param isInPictureInPictureMode}.
       */
      public void onPictureInPictureModeChanged(boolean isInPictureInPictureMode,
              Configuration newConfig) {
          onPictureInPictureModeChanged(isInPictureInPictureMode);
      }
  
      /**
       * Called by the system when the activity changes to and from picture-in-picture mode. This is
       * generally tied to {@link Activity#onPictureInPictureModeChanged} of the containing Activity.
       *
       * @param isInPictureInPictureMode True if the activity is in picture-in-picture mode.
       *
       * @deprecated Use {@link #onPictureInPictureModeChanged(boolean, Configuration)} instead.
       */
      @Deprecated
      public void onPictureInPictureModeChanged(boolean isInPictureInPictureMode) {
      }
  
      @CallSuper
      public void onConfigurationChanged(Configuration newConfig) {
          mCalled = true;
      }
  
      /**
       * Called when the Fragment is no longer resumed.  This is generally
       * tied to {@link Activity#onPause() Activity.onPause} of the containing
       * Activity's lifecycle.
       */
      @CallSuper
      public void onPause() {
          mCalled = true;
      }
  
      /**
       * Called when the Fragment is no longer started.  This is generally
       * tied to {@link Activity#onStop() Activity.onStop} of the containing
       * Activity's lifecycle.
       */
      @CallSuper
      public void onStop() {
          mCalled = true;
      }
  
      @CallSuper
      public void onLowMemory() {
          mCalled = true;
      }
  
      @CallSuper
      public void onTrimMemory(int level) {
          mCalled = true;
      }
  
      /**
       * Called when the view previously created by {@link #onCreateView} has
       * been detached from the fragment.  The next time the fragment needs
       * to be displayed, a new view will be created.  This is called
       * after {@link #onStop()} and before {@link #onDestroy()}.  It is called
       * <em>regardless</em> of whether {@link #onCreateView} returned a
       * non-null view.  Internally it is called after the view's state has
       * been saved but before it has been removed from its parent.
       */
      @CallSuper
      public void onDestroyView() {
          mCalled = true;
      }
  
      /**
       * Called when the fragment is no longer in use.  This is called
       * after {@link #onStop()} and before {@link #onDetach()}.
       */
      @CallSuper
      public void onDestroy() {
          mCalled = true;
          //Log.v("foo", "onDestroy: mCheckedForLoaderManager=" + mCheckedForLoaderManager
          //        + " mLoaderManager=" + mLoaderManager);
          if (!mCheckedForLoaderManager) {
              mCheckedForLoaderManager = true;
              mLoaderManager = mHost.getLoaderManager(mWho, mLoadersStarted, false);
          }
          if (mLoaderManager != null) {
              mLoaderManager.doDestroy();
          }
      }
  
      /**
       * Called by the fragment manager once this fragment has been removed,
       * so that we don't have any left-over state if the application decides
       * to re-use the instance.  This only clears state that the framework
       * internally manages, not things the application sets.
       */
      void initState() {
          mIndex = -1;
          mWho = null;
          mAdded = false;
          mRemoving = false;
          mFromLayout = false;
          mInLayout = false;
          mRestored = false;
          mBackStackNesting = 0;
          mFragmentManager = null;
          mChildFragmentManager = null;
          mHost = null;
          mFragmentId = 0;
          mContainerId = 0;
          mTag = null;
          mHidden = false;
          mDetached = false;
          mRetaining = false;
          mLoaderManager = null;
          mLoadersStarted = false;
          mCheckedForLoaderManager = false;
      }
  
      /**
       * Called when the fragment is no longer attached to its activity.  This is called after
       * {@link #onDestroy()}, except in the cases where the fragment instance is retained across
       * Activity re-creation (see {@link #setRetainInstance(boolean)}), in which case it is called
       * after {@link #onStop()}.
       */
      @CallSuper
      public void onDetach() {
          mCalled = true;
      }
  
      /**
       * Initialize the contents of the Activity's standard options menu.  You
       * should place your menu items in to <var>menu</var>.  For this method
       * to be called, you must have first called {@link #setHasOptionsMenu}.  See
       * {@link Activity#onCreateOptionsMenu(Menu) Activity.onCreateOptionsMenu}
       * for more information.
       *
       * @param menu The options menu in which you place your items.
       *
       * @see #setHasOptionsMenu
       * @see #onPrepareOptionsMenu
       * @see #onOptionsItemSelected
       */
      public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
      }
  
      /**
       * Prepare the Screen's standard options menu to be displayed.  This is
       * called right before the menu is shown, every time it is shown.  You can
       * use this method to efficiently enable/disable items or otherwise
       * dynamically modify the contents.  See
       * {@link Activity#onPrepareOptionsMenu(Menu) Activity.onPrepareOptionsMenu}
       * for more information.
       *
       * @param menu The options menu as last shown or first initialized by
       *             onCreateOptionsMenu().
       *
       * @see #setHasOptionsMenu
       * @see #onCreateOptionsMenu
       */
      public void onPrepareOptionsMenu(Menu menu) {
      }
  
      /**
       * Called when this fragment's option menu items are no longer being
       * included in the overall options menu.  Receiving this call means that
       * the menu needed to be rebuilt, but this fragment's items were not
       * included in the newly built menu (its {@link #onCreateOptionsMenu(Menu, MenuInflater)}
       * was not called).
       */
      public void onDestroyOptionsMenu() {
      }
  
      /**
       * This hook is called whenever an item in your options menu is selected.
       * The default implementation simply returns false to have the normal
       * processing happen (calling the item's Runnable or sending a message to
       * its Handler as appropriate).  You can use this method for any items
       * for which you would like to do processing without those other
       * facilities.
       *
       * <p>Derived classes should call through to the base class for it to
       * perform the default menu handling.
       *
       * @param item The menu item that was selected.
       *
       * @return boolean Return false to allow normal menu processing to
       *         proceed, true to consume it here.
       *
       * @see #onCreateOptionsMenu
       */
      public boolean onOptionsItemSelected(MenuItem item) {
          return false;
      }
  
      /**
       * This hook is called whenever the options menu is being closed (either by the user canceling
       * the menu with the back/menu button, or when an item is selected).
       *
       * @param menu The options menu as last shown or first initialized by
       *             onCreateOptionsMenu().
       */
      public void onOptionsMenuClosed(Menu menu) {
      }
  
      /**
       * Called when a context menu for the {@code view} is about to be shown.
       * Unlike {@link #onCreateOptionsMenu}, this will be called every
       * time the context menu is about to be shown and should be populated for
       * the view (or item inside the view for {@link AdapterView} subclasses,
       * this can be found in the {@code menuInfo})).
       * <p>
       * Use {@link #onContextItemSelected(android.view.MenuItem)} to know when an
       * item has been selected.
       * <p>
       * The default implementation calls up to
       * {@link Activity#onCreateContextMenu Activity.onCreateContextMenu}, though
       * you can not call this implementation if you don't want that behavior.
       * <p>
       * It is not safe to hold onto the context menu after this method returns.
       * {@inheritDoc}
       */
      public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
          getActivity().onCreateContextMenu(menu, v, menuInfo);
      }
  
      /**
       * Registers a context menu to be shown for the given view (multiple views
       * can show the context menu). This method will set the
       * {@link OnCreateContextMenuListener} on the view to this fragment, so
       * {@link #onCreateContextMenu(ContextMenu, View, ContextMenuInfo)} will be
       * called when it is time to show the context menu.
       *
       * @see #unregisterForContextMenu(View)
       * @param view The view that should show a context menu.
       */
      public void registerForContextMenu(View view) {
          view.setOnCreateContextMenuListener(this);
      }
  
      /**
       * Prevents a context menu to be shown for the given view. This method will
       * remove the {@link OnCreateContextMenuListener} on the view.
       *
       * @see #registerForContextMenu(View)
       * @param view The view that should stop showing a context menu.
       */
      public void unregisterForContextMenu(View view) {
          view.setOnCreateContextMenuListener(null);
      }
  
      /**
       * This hook is called whenever an item in a context menu is selected. The
       * default implementation simply returns false to have the normal processing
       * happen (calling the item's Runnable or sending a message to its Handler
       * as appropriate). You can use this method for any items for which you
       * would like to do processing without those other facilities.
       * <p>
       * Use {@link MenuItem#getMenuInfo()} to get extra information set by the
       * View that added this menu item.
       * <p>
       * Derived classes should call through to the base class for it to perform
       * the default menu handling.
       *
       * @param item The context menu item that was selected.
       * @return boolean Return false to allow normal context menu processing to
       *         proceed, true to consume it here.
       */
      public boolean onContextItemSelected(MenuItem item) {
          return false;
      }
  
      /**
       * When custom transitions are used with Fragments, the enter transition callback
       * is called when this Fragment is attached or detached when not popping the back stack.
       *
       * @param callback Used to manipulate the shared element transitions on this Fragment
       *                 when added not as a pop from the back stack.
       */
      public void setEnterSharedElementCallback(SharedElementCallback callback) {
          if (callback == null) {
              if (mAnimationInfo == null) {
                  return; // already a null callback
              }
              callback = SharedElementCallback.NULL_CALLBACK;
          }
          ensureAnimationInfo().mEnterTransitionCallback = callback;
      }
  
      /**
       * When custom transitions are used with Fragments, the exit transition callback
       * is called when this Fragment is attached or detached when popping the back stack.
       *
       * @param callback Used to manipulate the shared element transitions on this Fragment
       *                 when added as a pop from the back stack.
       */
      public void setExitSharedElementCallback(SharedElementCallback callback) {
          if (callback == null) {
              if (mAnimationInfo == null) {
                  return; // already a null callback
              }
              callback = SharedElementCallback.NULL_CALLBACK;
          }
          ensureAnimationInfo().mExitTransitionCallback = callback;
      }
  
      /**
       * Sets the Transition that will be used to move Views into the initial scene. The entering
       * Views will be those that are regular Views or ViewGroups that have
       * {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
       * {@link android.transition.Visibility} as entering is governed by changing visibility from
       * {@link View#INVISIBLE} to {@link View#VISIBLE}. If <code>transition</code> is null,
       * entering Views will remain unaffected.
       *
       * @param transition The Transition to use to move Views into the initial Scene.
       * @attr ref android.R.styleable#Fragment_fragmentEnterTransition
       */
      public void setEnterTransition(Transition transition) {
          if (shouldChangeTransition(transition, null)) {
              ensureAnimationInfo().mEnterTransition = transition;
          }
      }
  
      /**
       * Returns the Transition that will be used to move Views into the initial scene. The entering
       * Views will be those that are regular Views or ViewGroups that have
       * {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
       * {@link android.transition.Visibility} as entering is governed by changing visibility from
       * {@link View#INVISIBLE} to {@link View#VISIBLE}.
       *
       * @return the Transition to use to move Views into the initial Scene.
       * @attr ref android.R.styleable#Fragment_fragmentEnterTransition
       */
      public Transition getEnterTransition() {
          if (mAnimationInfo == null) {
              return null;
          }
          return mAnimationInfo.mEnterTransition;
      }
  
      /**
       * Sets the Transition that will be used to move Views out of the scene when the Fragment is
       * preparing to be removed, hidden, or detached because of popping the back stack. The exiting
       * Views will be those that are regular Views or ViewGroups that have
       * {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
       * {@link android.transition.Visibility} as entering is governed by changing visibility from
       * {@link View#VISIBLE} to {@link View#INVISIBLE}. If <code>transition</code> is null,
       * entering Views will remain unaffected. If nothing is set, the default will be to
       * use the same value as set in {@link #setEnterTransition(android.transition.Transition)}.
       *
       * @param transition The Transition to use to move Views out of the Scene when the Fragment
       *                   is preparing to close.
       * @attr ref android.R.styleable#Fragment_fragmentExitTransition
       */
      public void setReturnTransition(Transition transition) {
          if (shouldChangeTransition(transition, USE_DEFAULT_TRANSITION)) {
              ensureAnimationInfo().mReturnTransition = transition;
          }
      }
  
      /**
       * Returns the Transition that will be used to move Views out of the scene when the Fragment is
       * preparing to be removed, hidden, or detached because of popping the back stack. The exiting
       * Views will be those that are regular Views or ViewGroups that have
       * {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
       * {@link android.transition.Visibility} as entering is governed by changing visibility from
       * {@link View#VISIBLE} to {@link View#INVISIBLE}. If <code>transition</code> is null,
       * entering Views will remain unaffected.
       *
       * @return the Transition to use to move Views out of the Scene when the Fragment
       *         is preparing to close.
       * @attr ref android.R.styleable#Fragment_fragmentExitTransition
       */
      public Transition getReturnTransition() {
          if (mAnimationInfo == null) {
              return null;
          }
          return mAnimationInfo.mReturnTransition == USE_DEFAULT_TRANSITION ? getEnterTransition()
                  : mAnimationInfo.mReturnTransition;
      }
  
      /**
       * Sets the Transition that will be used to move Views out of the scene when the
       * fragment is removed, hidden, or detached when not popping the back stack.
       * The exiting Views will be those that are regular Views or ViewGroups that
       * have {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
       * {@link android.transition.Visibility} as exiting is governed by changing visibility
       * from {@link View#VISIBLE} to {@link View#INVISIBLE}. If transition is null, the views will
       * remain unaffected.
       *
       * @param transition The Transition to use to move Views out of the Scene when the Fragment
       *                   is being closed not due to popping the back stack.
       * @attr ref android.R.styleable#Fragment_fragmentExitTransition
       */
      public void setExitTransition(Transition transition) {
          if (shouldChangeTransition(transition, null)) {
              ensureAnimationInfo().mExitTransition = transition;
          }
      }
  
      /**
       * Returns the Transition that will be used to move Views out of the scene when the
       * fragment is removed, hidden, or detached when not popping the back stack.
       * The exiting Views will be those that are regular Views or ViewGroups that
       * have {@link ViewGroup#isTransitionGroup} return true. Typical Transitions will extend
       * {@link android.transition.Visibility} as exiting is governed by changing visibility
       * from {@link View#VISIBLE} to {@link View#INVISIBLE}. If transition is null, the views will
       * remain unaffected.
       *
       * @return the Transition to use to move Views out of the Scene when the Fragment
       *         is being closed not due to popping the back stack.
       * @attr ref android.R.styleable#Fragment_fragmentExitTransition
       */
      public Transition getExitTransition() {
          if (mAnimationInfo == null) {
              return null;
          }
          return mAnimationInfo.mExitTransition;
      }
  
      /**
       * Sets the Transition that will be used to move Views in to the scene when returning due
       * to popping a back stack. The entering Views will be those that are regular Views
       * or ViewGroups that have {@link ViewGroup#isTransitionGroup} return true. Typical Transitions
       * will extend {@link android.transition.Visibility} as exiting is governed by changing
       * visibility from {@link View#VISIBLE} to {@link View#INVISIBLE}. If transition is null,
       * the views will remain unaffected. If nothing is set, the default will be to use the same
       * transition as {@link #setExitTransition(android.transition.Transition)}.
       *
       * @param transition The Transition to use to move Views into the scene when reentering from a
       *                   previously-started Activity.
       * @attr ref android.R.styleable#Fragment_fragmentReenterTransition
       */
      public void setReenterTransition(Transition transition) {
          if (shouldChangeTransition(transition, USE_DEFAULT_TRANSITION)) {
              ensureAnimationInfo().mReenterTransition = transition;
          }
      }
  
      /**
       * Returns the Transition that will be used to move Views in to the scene when returning due
       * to popping a back stack. The entering Views will be those that are regular Views
       * or ViewGroups that have {@link ViewGroup#isTransitionGroup} return true. Typical Transitions
       * will extend {@link android.transition.Visibility} as exiting is governed by changing
       * visibility from {@link View#VISIBLE} to {@link View#INVISIBLE}. If transition is null,
       * the views will remain unaffected. If nothing is set, the default will be to use the same
       * transition as {@link #setExitTransition(android.transition.Transition)}.
       *
       * @return the Transition to use to move Views into the scene when reentering from a
       *                   previously-started Activity.
       * @attr ref android.R.styleable#Fragment_fragmentReenterTransition
       */
      public Transition getReenterTransition() {
          if (mAnimationInfo == null) {
              return null;
          }
          return mAnimationInfo.mReenterTransition == USE_DEFAULT_TRANSITION ? getExitTransition()
                  : mAnimationInfo.mReenterTransition;
      }
  
      /**
       * Sets the Transition that will be used for shared elements transferred into the content
       * Scene. Typical Transitions will affect size and location, such as
       * {@link android.transition.ChangeBounds}. A null
       * value will cause transferred shared elements to blink to the final position.
       *
       * @param transition The Transition to use for shared elements transferred into the content
       *                   Scene.
       * @attr ref android.R.styleable#Fragment_fragmentSharedElementEnterTransition
       */
      public void setSharedElementEnterTransition(Transition transition) {
          if (shouldChangeTransition(transition, null)) {
              ensureAnimationInfo().mSharedElementEnterTransition = transition;
          }
      }
  
      /**
       * Returns the Transition that will be used for shared elements transferred into the content
       * Scene. Typical Transitions will affect size and location, such as
       * {@link android.transition.ChangeBounds}. A null
       * value will cause transferred shared elements to blink to the final position.
       *
       * @return The Transition to use for shared elements transferred into the content
       *                   Scene.
       * @attr ref android.R.styleable#Fragment_fragmentSharedElementEnterTransition
       */
      public Transition getSharedElementEnterTransition() {
          if (mAnimationInfo == null) {
              return null;
          }
          return mAnimationInfo.mSharedElementEnterTransition;
      }
  
      /**
       * Sets the Transition that will be used for shared elements transferred back during a
       * pop of the back stack. This Transition acts in the leaving Fragment.
       * Typical Transitions will affect size and location, such as
       * {@link android.transition.ChangeBounds}. A null
       * value will cause transferred shared elements to blink to the final position.
       * If no value is set, the default will be to use the same value as
       * {@link #setSharedElementEnterTransition(android.transition.Transition)}.
       *
       * @param transition The Transition to use for shared elements transferred out of the content
       *                   Scene.
       * @attr ref android.R.styleable#Fragment_fragmentSharedElementReturnTransition
       */
      public void setSharedElementReturnTransition(Transition transition) {
          if (shouldChangeTransition(transition, USE_DEFAULT_TRANSITION)) {
              ensureAnimationInfo().mSharedElementReturnTransition = transition;
          }
      }
  
      /**
       * Return the Transition that will be used for shared elements transferred back during a
       * pop of the back stack. This Transition acts in the leaving Fragment.
       * Typical Transitions will affect size and location, such as
       * {@link android.transition.ChangeBounds}. A null
       * value will cause transferred shared elements to blink to the final position.
       * If no value is set, the default will be to use the same value as
       * {@link #setSharedElementEnterTransition(android.transition.Transition)}.
       *
       * @return The Transition to use for shared elements transferred out of the content
       *                   Scene.
       * @attr ref android.R.styleable#Fragment_fragmentSharedElementReturnTransition
       */
      public Transition getSharedElementReturnTransition() {
          if (mAnimationInfo == null) {
              return null;
          }
          return mAnimationInfo.mSharedElementReturnTransition == USE_DEFAULT_TRANSITION
                  ? getSharedElementEnterTransition()
                  : mAnimationInfo.mSharedElementReturnTransition;
      }
  
      /**
       * Sets whether the exit transition and enter transition overlap or not.
       * When true, the enter transition will start as soon as possible. When false, the
       * enter transition will wait until the exit transition completes before starting.
       *
       * @param allow true to start the enter transition when possible or false to
       *              wait until the exiting transition completes.
       * @attr ref android.R.styleable#Fragment_fragmentAllowEnterTransitionOverlap
       */
      public void setAllowEnterTransitionOverlap(boolean allow) {
          ensureAnimationInfo().mAllowEnterTransitionOverlap = allow;
      }
  
      /**
       * Returns whether the exit transition and enter transition overlap or not.
       * When true, the enter transition will start as soon as possible. When false, the
       * enter transition will wait until the exit transition completes before starting.
       *
       * @return true when the enter transition should start as soon as possible or false to
       * when it should wait until the exiting transition completes.
       * @attr ref android.R.styleable#Fragment_fragmentAllowEnterTransitionOverlap
       */
      public boolean getAllowEnterTransitionOverlap() {
          return (mAnimationInfo == null || mAnimationInfo.mAllowEnterTransitionOverlap == null)
                  ? true : mAnimationInfo.mAllowEnterTransitionOverlap;
      }
  
      /**
       * Sets whether the return transition and reenter transition overlap or not.
       * When true, the reenter transition will start as soon as possible. When false, the
       * reenter transition will wait until the return transition completes before starting.
       *
       * @param allow true to start the reenter transition when possible or false to wait until the
       *              return transition completes.
       * @attr ref android.R.styleable#Fragment_fragmentAllowReturnTransitionOverlap
       */
      public void setAllowReturnTransitionOverlap(boolean allow) {
          ensureAnimationInfo().mAllowReturnTransitionOverlap = allow;
      }
  
      /**
       * Returns whether the return transition and reenter transition overlap or not.
       * When true, the reenter transition will start as soon as possible. When false, the
       * reenter transition will wait until the return transition completes before starting.
       *
       * @return true to start the reenter transition when possible or false to wait until the
       *         return transition completes.
       * @attr ref android.R.styleable#Fragment_fragmentAllowReturnTransitionOverlap
       */
      public boolean getAllowReturnTransitionOverlap() {
          return (mAnimationInfo == null || mAnimationInfo.mAllowReturnTransitionOverlap == null)
                  ? true : mAnimationInfo.mAllowReturnTransitionOverlap;
      }
  
      /**
       * Postpone the entering Fragment transition until {@link #startPostponedEnterTransition()}
       * or {@link FragmentManager#executePendingTransactions()} has been called.
       * <p>
       * This method gives the Fragment the ability to delay Fragment animations
       * until all data is loaded. Until then, the added, shown, and
       * attached Fragments will be INVISIBLE and removed, hidden, and detached Fragments won't
       * be have their Views removed. The transaction runs when all postponed added Fragments in the
       * transaction have called {@link #startPostponedEnterTransition()}.
       * <p>
       * This method should be called before being added to the FragmentTransaction or
       * in {@link #onCreate(Bundle)}, {@link #onAttach(Context)}, or
       * {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)}}.
       * {@link #startPostponedEnterTransition()} must be called to allow the Fragment to
       * start the transitions.
       * <p>
       * When a FragmentTransaction is started that may affect a postponed FragmentTransaction,
       * based on which containers are in their operations, the postponed FragmentTransaction
       * will have its start triggered. The early triggering may result in faulty or nonexistent
       * animations in the postponed transaction. FragmentTransactions that operate only on
       * independent containers will not interfere with each other's postponement.
       * <p>
       * Calling postponeEnterTransition on Fragments with a null View will not postpone the
       * transition. Likewise, postponement only works if FragmentTransaction optimizations are
       * enabled.
       *
       * @see Activity#postponeEnterTransition()
       * @see FragmentTransaction#setReorderingAllowed(boolean)
       */
      public void postponeEnterTransition() {
          ensureAnimationInfo().mEnterTransitionPostponed = true;
      }
  
      /**
       * Begin postponed transitions after {@link #postponeEnterTransition()} was called.
       * If postponeEnterTransition() was called, you must call startPostponedEnterTransition()
       * or {@link FragmentManager#executePendingTransactions()} to complete the FragmentTransaction.
       * If postponement was interrupted with {@link FragmentManager#executePendingTransactions()},
       * before {@code startPostponedEnterTransition()}, animations may not run or may execute
       * improperly.
       *
       * @see Activity#startPostponedEnterTransition()
       */
      public void startPostponedEnterTransition() {
          if (mFragmentManager == null || mFragmentManager.mHost == null) {
                  ensureAnimationInfo().mEnterTransitionPostponed = false;
          } else if (Looper.myLooper() != mFragmentManager.mHost.getHandler().getLooper()) {
              mFragmentManager.mHost.getHandler().
                      postAtFrontOfQueue(this::callStartTransitionListener);
          } else {
              callStartTransitionListener();
          }
      }
  
      /**
       * Calls the start transition listener. This must be called on the UI thread.
       */
      private void callStartTransitionListener() {
          final OnStartEnterTransitionListener listener;
          if (mAnimationInfo == null) {
              listener = null;
          } else {
              mAnimationInfo.mEnterTransitionPostponed = false;
              listener = mAnimationInfo.mStartEnterTransitionListener;
              mAnimationInfo.mStartEnterTransitionListener = null;
          }
          if (listener != null) {
              listener.onStartEnterTransition();
          }
      }
  
      /**
       * Returns true if mAnimationInfo is not null or the transition differs from the default value.
       * This is broken out to ensure mAnimationInfo is properly locked when checking.
       */
      private boolean shouldChangeTransition(Transition transition, Transition defaultValue) {
          if (transition == defaultValue) {
              return mAnimationInfo != null;
          }
          return true;
      }
  
      /**
       * Print the Fragments'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 The PrintWriter to which you should dump your state.  This will be
       * closed for you after you return.
       * @param args additional arguments to the dump request.
       */
      public void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) {
          writer.print(prefix); writer.print("mFragmentId=#");
          writer.print(Integer.toHexString(mFragmentId));
          writer.print(" mContainerId=#");
          writer.print(Integer.toHexString(mContainerId));
          writer.print(" mTag="); writer.println(mTag);
          writer.print(prefix); writer.print("mState="); writer.print(mState);
          writer.print(" mIndex="); writer.print(mIndex);
          writer.print(" mWho="); writer.print(mWho);
          writer.print(" mBackStackNesting="); writer.println(mBackStackNesting);
          writer.print(prefix); writer.print("mAdded="); writer.print(mAdded);
          writer.print(" mRemoving="); writer.print(mRemoving);
          writer.print(" mFromLayout="); writer.print(mFromLayout);
          writer.print(" mInLayout="); writer.println(mInLayout);
          writer.print(prefix); writer.print("mHidden="); writer.print(mHidden);
          writer.print(" mDetached="); writer.print(mDetached);
          writer.print(" mMenuVisible="); writer.print(mMenuVisible);
          writer.print(" mHasMenu="); writer.println(mHasMenu);
          writer.print(prefix); writer.print("mRetainInstance="); writer.print(mRetainInstance);
          writer.print(" mRetaining="); writer.print(mRetaining);
          writer.print(" mUserVisibleHint="); writer.println(mUserVisibleHint);
          if (mFragmentManager != null) {
              writer.print(prefix); writer.print("mFragmentManager=");
              writer.println(mFragmentManager);
          }
          if (mHost != null) {
              writer.print(prefix); writer.print("mHost=");
              writer.println(mHost);
          }
          if (mParentFragment != null) {
              writer.print(prefix); writer.print("mParentFragment=");
              writer.println(mParentFragment);
          }
          if (mArguments != null) {
              writer.print(prefix); writer.print("mArguments="); writer.println(mArguments);
          }
          if (mSavedFragmentState != null) {
              writer.print(prefix); writer.print("mSavedFragmentState=");
              writer.println(mSavedFragmentState);
          }
          if (mSavedViewState != null) {
              writer.print(prefix); writer.print("mSavedViewState=");
              writer.println(mSavedViewState);
          }
          if (mTarget != null) {
              writer.print(prefix); writer.print("mTarget="); writer.print(mTarget);
              writer.print(" mTargetRequestCode=");
              writer.println(mTargetRequestCode);
          }
          if (getNextAnim() != 0) {
              writer.print(prefix); writer.print("mNextAnim="); writer.println(getNextAnim());
          }
          if (mContainer != null) {
              writer.print(prefix); writer.print("mContainer="); writer.println(mContainer);
          }
          if (mView != null) {
              writer.print(prefix); writer.print("mView="); writer.println(mView);
          }
          if (getAnimatingAway() != null) {
              writer.print(prefix); writer.print("mAnimatingAway=");
              writer.println(getAnimatingAway());
              writer.print(prefix); writer.print("mStateAfterAnimating=");
              writer.println(getStateAfterAnimating());
          }
          if (mLoaderManager != null) {
              writer.print(prefix); writer.println("Loader Manager:");
              mLoaderManager.dump(prefix + "  ", fd, writer, args);
          }
          if (mChildFragmentManager != null) {
              writer.print(prefix); writer.println("Child " + mChildFragmentManager + ":");
              mChildFragmentManager.dump(prefix + "  ", fd, writer, args);
          }
      }
  
      Fragment findFragmentByWho(String who) {
          if (who.equals(mWho)) {
              return this;
          }
          if (mChildFragmentManager != null) {
              return mChildFragmentManager.findFragmentByWho(who);
          }
          return null;
      }
  
      void instantiateChildFragmentManager() {
          mChildFragmentManager = new FragmentManagerImpl();
          mChildFragmentManager.attachController(mHost, new FragmentContainer() {
              @Override
              @Nullable
              public <T extends View> T onFindViewById(int id) {
                  if (mView == null) {
                      throw new IllegalStateException("Fragment does not have a view");
                  }
                  return mView.findViewById(id);
              }
  
              @Override
              public boolean onHasView() {
                  return (mView != null);
              }
          }, this);
      }
  
      void performCreate(Bundle savedInstanceState) {
          if (mChildFragmentManager != null) {
              mChildFragmentManager.noteStateNotSaved();
          }
          mState = CREATED;
          mCalled = false;
          onCreate(savedInstanceState);
          mIsCreated = true;
          if (!mCalled) {
              throw new SuperNotCalledException("Fragment " + this
                      + " did not call through to super.onCreate()");
          }
          final Context context = getContext();
          final int version = context != null ? context.getApplicationInfo().targetSdkVersion : 0;
          if (version < Build.VERSION_CODES.N) {
              restoreChildFragmentState(savedInstanceState, false);
          }
      }
  
      View performCreateView(LayoutInflater inflater, ViewGroup container,
              Bundle savedInstanceState) {
          if (mChildFragmentManager != null) {
              mChildFragmentManager.noteStateNotSaved();
          }
          mPerformedCreateView = true;
          return onCreateView(inflater, container, savedInstanceState);
      }
  
      void performActivityCreated(Bundle savedInstanceState) {
          if (mChildFragmentManager != null) {
              mChildFragmentManager.noteStateNotSaved();
          }
          mState = ACTIVITY_CREATED;
          mCalled = false;
          onActivityCreated(savedInstanceState);
          if (!mCalled) {
              throw new SuperNotCalledException("Fragment " + this
                      + " did not call through to super.onActivityCreated()");
          }
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchActivityCreated();
          }
      }
  
      void performStart() {
          if (mChildFragmentManager != null) {
              mChildFragmentManager.noteStateNotSaved();
              mChildFragmentManager.execPendingActions();
          }
          mState = STARTED;
          mCalled = false;
          onStart();
          if (!mCalled) {
              throw new SuperNotCalledException("Fragment " + this
                      + " did not call through to super.onStart()");
          }
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchStart();
          }
          if (mLoaderManager != null) {
              mLoaderManager.doReportStart();
          }
      }
  
      void performResume() {
          if (mChildFragmentManager != null) {
              mChildFragmentManager.noteStateNotSaved();
              mChildFragmentManager.execPendingActions();
          }
          mState = RESUMED;
          mCalled = false;
          onResume();
          if (!mCalled) {
              throw new SuperNotCalledException("Fragment " + this
                      + " did not call through to super.onResume()");
          }
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchResume();
              mChildFragmentManager.execPendingActions();
          }
      }
  
      void noteStateNotSaved() {
          if (mChildFragmentManager != null) {
              mChildFragmentManager.noteStateNotSaved();
          }
      }
  
      @Deprecated
      void performMultiWindowModeChanged(boolean isInMultiWindowMode) {
          onMultiWindowModeChanged(isInMultiWindowMode);
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchMultiWindowModeChanged(isInMultiWindowMode);
          }
      }
  
      void performMultiWindowModeChanged(boolean isInMultiWindowMode, Configuration newConfig) {
          onMultiWindowModeChanged(isInMultiWindowMode, newConfig);
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchMultiWindowModeChanged(isInMultiWindowMode, newConfig);
          }
      }
  
      @Deprecated
      void performPictureInPictureModeChanged(boolean isInPictureInPictureMode) {
          onPictureInPictureModeChanged(isInPictureInPictureMode);
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchPictureInPictureModeChanged(isInPictureInPictureMode);
          }
      }
  
      void performPictureInPictureModeChanged(boolean isInPictureInPictureMode,
              Configuration newConfig) {
          onPictureInPictureModeChanged(isInPictureInPictureMode, newConfig);
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchPictureInPictureModeChanged(isInPictureInPictureMode,
                      newConfig);
          }
      }
  
      void performConfigurationChanged(Configuration newConfig) {
          onConfigurationChanged(newConfig);
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchConfigurationChanged(newConfig);
          }
      }
  
      void performLowMemory() {
          onLowMemory();
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchLowMemory();
          }
      }
  
      void performTrimMemory(int level) {
          onTrimMemory(level);
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchTrimMemory(level);
          }
      }
  
      boolean performCreateOptionsMenu(Menu menu, MenuInflater inflater) {
          boolean show = false;
          if (!mHidden) {
              if (mHasMenu && mMenuVisible) {
                  show = true;
                  onCreateOptionsMenu(menu, inflater);
              }
              if (mChildFragmentManager != null) {
                  show |= mChildFragmentManager.dispatchCreateOptionsMenu(menu, inflater);
              }
          }
          return show;
      }
  
      boolean performPrepareOptionsMenu(Menu menu) {
          boolean show = false;
          if (!mHidden) {
              if (mHasMenu && mMenuVisible) {
                  show = true;
                  onPrepareOptionsMenu(menu);
              }
              if (mChildFragmentManager != null) {
                  show |= mChildFragmentManager.dispatchPrepareOptionsMenu(menu);
              }
          }
          return show;
      }
  
      boolean performOptionsItemSelected(MenuItem item) {
          if (!mHidden) {
              if (mHasMenu && mMenuVisible) {
                  if (onOptionsItemSelected(item)) {
                      return true;
                  }
              }
              if (mChildFragmentManager != null) {
                  if (mChildFragmentManager.dispatchOptionsItemSelected(item)) {
                      return true;
                  }
              }
          }
          return false;
      }
  
      boolean performContextItemSelected(MenuItem item) {
          if (!mHidden) {
              if (onContextItemSelected(item)) {
                  return true;
              }
              if (mChildFragmentManager != null) {
                  if (mChildFragmentManager.dispatchContextItemSelected(item)) {
                      return true;
                  }
              }
          }
          return false;
      }
  
      void performOptionsMenuClosed(Menu menu) {
          if (!mHidden) {
              if (mHasMenu && mMenuVisible) {
                  onOptionsMenuClosed(menu);
              }
              if (mChildFragmentManager != null) {
                  mChildFragmentManager.dispatchOptionsMenuClosed(menu);
              }
          }
      }
  
      void performSaveInstanceState(Bundle outState) {
          onSaveInstanceState(outState);
          if (mChildFragmentManager != null) {
              Parcelable p = mChildFragmentManager.saveAllState();
              if (p != null) {
                  outState.putParcelable(Activity.FRAGMENTS_TAG, p);
              }
          }
      }
  
      void performPause() {
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchPause();
          }
          mState = STARTED;
          mCalled = false;
          onPause();
          if (!mCalled) {
              throw new SuperNotCalledException("Fragment " + this
                      + " did not call through to super.onPause()");
          }
      }
  
      void performStop() {
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchStop();
          }
          mState = STOPPED;
          mCalled = false;
          onStop();
          if (!mCalled) {
              throw new SuperNotCalledException("Fragment " + this
                      + " did not call through to super.onStop()");
          }
  
          if (mLoadersStarted) {
              mLoadersStarted = false;
              if (!mCheckedForLoaderManager) {
                  mCheckedForLoaderManager = true;
                  mLoaderManager = mHost.getLoaderManager(mWho, mLoadersStarted, false);
              }
              if (mLoaderManager != null) {
                  if (mHost.getRetainLoaders()) {
                      mLoaderManager.doRetain();
                  } else {
                      mLoaderManager.doStop();
                  }
              }
          }
      }
  
      void performDestroyView() {
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchDestroyView();
          }
          mState = CREATED;
          mCalled = false;
          onDestroyView();
          if (!mCalled) {
              throw new SuperNotCalledException("Fragment " + this
                      + " did not call through to super.onDestroyView()");
          }
          if (mLoaderManager != null) {
              mLoaderManager.doReportNextStart();
          }
          mPerformedCreateView = false;
      }
  
      void performDestroy() {
          if (mChildFragmentManager != null) {
              mChildFragmentManager.dispatchDestroy();
          }
          mState = INITIALIZING;
          mCalled = false;
          mIsCreated = false;
          onDestroy();
          if (!mCalled) {
              throw new SuperNotCalledException("Fragment " + this
                      + " did not call through to super.onDestroy()");
          }
          mChildFragmentManager = null;
      }
  
      void performDetach() {
          mCalled = false;
          onDetach();
          mLayoutInflater = null;
          if (!mCalled) {
              throw new SuperNotCalledException("Fragment " + this
                      + " did not call through to super.onDetach()");
          }
  
          // Destroy the child FragmentManager if we still have it here.
          // We won't unless we're retaining our instance and if we do,
          // our child FragmentManager instance state will have already been saved.
          if (mChildFragmentManager != null) {
              if (!mRetaining) {
                  throw new IllegalStateException("Child FragmentManager of " + this + " was not "
                          + " destroyed and this fragment is not retaining instance");
              }
              mChildFragmentManager.dispatchDestroy();
              mChildFragmentManager = null;
          }
      }
  
      void setOnStartEnterTransitionListener(OnStartEnterTransitionListener listener) {
          ensureAnimationInfo();
          if (listener == mAnimationInfo.mStartEnterTransitionListener) {
              return;
          }
          if (listener != null && mAnimationInfo.mStartEnterTransitionListener != null) {
              throw new IllegalStateException("Trying to set a replacement " +
                      "startPostponedEnterTransition on " + this);
          }
          if (mAnimationInfo.mEnterTransitionPostponed) {
              mAnimationInfo.mStartEnterTransitionListener = listener;
          }
          if (listener != null) {
              listener.startListening();
          }
      }
  
      private static Transition loadTransition(Context context, TypedArray typedArray,
              Transition currentValue, Transition defaultValue, int id) {
          if (currentValue != defaultValue) {
              return currentValue;
          }
          int transitionId = typedArray.getResourceId(id, 0);
          Transition transition = defaultValue;
          if (transitionId != 0 && transitionId != com.android.internal.R.transition.no_transition) {
              TransitionInflater inflater = TransitionInflater.from(context);
              transition = inflater.inflateTransition(transitionId);
              if (transition instanceof TransitionSet &&
                      ((TransitionSet)transition).getTransitionCount() == 0) {
                  transition = null;
              }
          }
          return transition;
      }
  
      private AnimationInfo ensureAnimationInfo() {
          if (mAnimationInfo == null) {
              mAnimationInfo = new AnimationInfo();
          }
          return mAnimationInfo;
      }
  
      int getNextAnim() {
          if (mAnimationInfo == null) {
              return 0;
          }
          return mAnimationInfo.mNextAnim;
      }
  
      void setNextAnim(int animResourceId) {
          if (mAnimationInfo == null && animResourceId == 0) {
              return; // no change!
          }
          ensureAnimationInfo().mNextAnim = animResourceId;
      }
  
      int getNextTransition() {
          if (mAnimationInfo == null) {
              return 0;
          }
          return mAnimationInfo.mNextTransition;
      }
  
      void setNextTransition(int nextTransition, int nextTransitionStyle) {
          if (mAnimationInfo == null && nextTransition == 0 && nextTransitionStyle == 0) {
              return; // no change!
          }
          ensureAnimationInfo();
          mAnimationInfo.mNextTransition = nextTransition;
          mAnimationInfo.mNextTransitionStyle = nextTransitionStyle;
      }
  
      int getNextTransitionStyle() {
          if (mAnimationInfo == null) {
              return 0;
          }
          return mAnimationInfo.mNextTransitionStyle;
      }
  
      SharedElementCallback getEnterTransitionCallback() {
          if (mAnimationInfo == null) {
              return SharedElementCallback.NULL_CALLBACK;
          }
          return mAnimationInfo.mEnterTransitionCallback;
      }
  
      SharedElementCallback getExitTransitionCallback() {
          if (mAnimationInfo == null) {
              return SharedElementCallback.NULL_CALLBACK;
          }
          return mAnimationInfo.mExitTransitionCallback;
      }
  
      Animator getAnimatingAway() {
          if (mAnimationInfo == null) {
              return null;
          }
          return mAnimationInfo.mAnimatingAway;
      }
  
      void setAnimatingAway(Animator animator) {
          ensureAnimationInfo().mAnimatingAway = animator;
      }
  
      int getStateAfterAnimating() {
          if (mAnimationInfo == null) {
              return 0;
          }
          return mAnimationInfo.mStateAfterAnimating;
      }
  
      void setStateAfterAnimating(int state) {
          ensureAnimationInfo().mStateAfterAnimating = state;
      }
  
      boolean isPostponed() {
          if (mAnimationInfo == null) {
              return false;
          }
          return mAnimationInfo.mEnterTransitionPostponed;
      }
  
      boolean isHideReplaced() {
          if (mAnimationInfo == null) {
              return false;
          }
          return mAnimationInfo.mIsHideReplaced;
      }
  
      void setHideReplaced(boolean replaced) {
          ensureAnimationInfo().mIsHideReplaced = replaced;
      }
  
      /**
       * Used internally to be notified when {@link #startPostponedEnterTransition()} has
       * been called. This listener will only be called once and then be removed from the
       * listeners.
       */
      interface OnStartEnterTransitionListener {
          void onStartEnterTransition();
          void startListening();
      }
  
      /**
       * Contains all the animation and transition information for a fragment. This will only
       * be instantiated for Fragments that have Views.
       */
      static class AnimationInfo {
          // Non-null if the fragment's view hierarchy is currently animating away,
          // meaning we need to wait a bit on completely destroying it.  This is the
          // animation that is running.
          Animator mAnimatingAway;
  
          // If mAnimatingAway != null, this is the state we should move to once the
          // animation is done.
          int mStateAfterAnimating;
  
          // If app has requested a specific animation, this is the one to use.
          int mNextAnim;
  
          // If app has requested a specific transition, this is the one to use.
          int mNextTransition;
  
          // If app has requested a specific transition style, this is the one to use.
          int mNextTransitionStyle;
  
          private Transition mEnterTransition = null;
          private Transition mReturnTransition = USE_DEFAULT_TRANSITION;
          private Transition mExitTransition = null;
          private Transition mReenterTransition = USE_DEFAULT_TRANSITION;
          private Transition mSharedElementEnterTransition = null;
          private Transition mSharedElementReturnTransition = USE_DEFAULT_TRANSITION;
          private Boolean mAllowReturnTransitionOverlap;
          private Boolean mAllowEnterTransitionOverlap;
  
          SharedElementCallback mEnterTransitionCallback = SharedElementCallback.NULL_CALLBACK;
          SharedElementCallback mExitTransitionCallback = SharedElementCallback.NULL_CALLBACK;
  
          // True when postponeEnterTransition has been called and startPostponeEnterTransition
          // hasn't been called yet.
          boolean mEnterTransitionPostponed;
  
          // Listener to wait for startPostponeEnterTransition. After being called, it will
          // be set to null
          OnStartEnterTransitionListener mStartEnterTransitionListener;
  
          // True if the View was hidden, but the transition is handling the hide
          boolean mIsHideReplaced;
      }
  }
  