content: /*
   * Copyright (C) 2006 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.widget;
  
  import android.annotation.Nullable;
  import android.database.DataSetObserver;
  import android.view.View;
  import android.view.ViewGroup;
  
  /**
   * An Adapter object acts as a bridge between an {@link AdapterView} and the
   * underlying data for that view. The Adapter provides access to the data items.
   * The Adapter is also responsible for making a {@link android.view.View} for
   * each item in the data set.
   * 
   * @see android.widget.ArrayAdapter
   * @see android.widget.CursorAdapter
   * @see android.widget.SimpleCursorAdapter
   */
  public interface Adapter {
      /**
       * Register an observer that is called when changes happen to the data used by this adapter.
       *
       * @param observer the object that gets notified when the data set changes.
       */
      void registerDataSetObserver(DataSetObserver observer);
  
      /**
       * Unregister an observer that has previously been registered with this
       * adapter via {@link #registerDataSetObserver}.
       *
       * @param observer the object to unregister.
       */
      void unregisterDataSetObserver(DataSetObserver observer);
  
      /**
       * How many items are in the data set represented by this Adapter.
       * 
       * @return Count of items.
       */
      int getCount();   
      
      /**
       * Get the data item associated with the specified position in the data set.
       * 
       * @param position Position of the item whose data we want within the adapter's 
       * data set.
       * @return The data at the specified position.
       */
      Object getItem(int position);
      
      /**
       * Get the row id associated with the specified position in the list.
       * 
       * @param position The position of the item within the adapter's data set whose row id we want.
       * @return The id of the item at the specified position.
       */
      long getItemId(int position);
      
      /**
       * Indicates whether the item ids are stable across changes to the
       * underlying data.
       * 
       * @return True if the same id always refers to the same object.
       */
      boolean hasStableIds();
      
      /**
       * Get a View that displays the data at the specified position in the data set. You can either
       * create a View manually or inflate it from an XML layout file. When the View is inflated, the
       * parent View (GridView, ListView...) will apply default layout parameters unless you use
       * {@link android.view.LayoutInflater#inflate(int, android.view.ViewGroup, boolean)}
       * to specify a root view and to prevent attachment to the root.
       * 
       * @param position The position of the item within the adapter's data set of the item whose view
       *        we want.
       * @param convertView The old view to reuse, if possible. Note: You should check that this view
       *        is non-null and of an appropriate type before using. If it is not possible to convert
       *        this view to display the correct data, this method can create a new view.
       *        Heterogeneous lists can specify their number of view types, so that this View is
       *        always of the right type (see {@link #getViewTypeCount()} and
       *        {@link #getItemViewType(int)}).
       * @param parent The parent that this view will eventually be attached to
       * @return A View corresponding to the data at the specified position.
       */
      View getView(int position, View convertView, ViewGroup parent);
  
      /**
       * An item view type that causes the {@link AdapterView} to ignore the item
       * view. For example, this can be used if the client does not want a
       * particular view to be given for conversion in
       * {@link #getView(int, View, ViewGroup)}.
       * 
       * @see #getItemViewType(int)
       * @see #getViewTypeCount()
       */
      static final int IGNORE_ITEM_VIEW_TYPE = AdapterView.ITEM_VIEW_TYPE_IGNORE;
      
      /**
       * Get the type of View that will be created by {@link #getView} for the specified item.
       * 
       * @param position The position of the item within the adapter's data set whose view type we
       *        want.
       * @return An integer representing the type of View. Two views should share the same type if one
       *         can be converted to the other in {@link #getView}. Note: Integers must be in the
       *         range 0 to {@link #getViewTypeCount} - 1. {@link #IGNORE_ITEM_VIEW_TYPE} can
       *         also be returned.
       * @see #IGNORE_ITEM_VIEW_TYPE
       */
      int getItemViewType(int position);
      
      /**
       * <p>
       * Returns the number of types of Views that will be created by
       * {@link #getView}. Each type represents a set of views that can be
       * converted in {@link #getView}. If the adapter always returns the same
       * type of View for all items, this method should return 1.
       * </p>
       * <p>
       * This method will only be called when the adapter is set on the {@link AdapterView}.
       * </p>
       * 
       * @return The number of types of Views that will be created by this adapter
       */
      int getViewTypeCount();
      
      static final int NO_SELECTION = Integer.MIN_VALUE;
   
       /**
        * @return true if this adapter doesn't contain any data.  This is used to determine
        * whether the empty view should be displayed.  A typical implementation will return
        * getCount() == 0 but since getCount() includes the headers and footers, specialized
        * adapters might want a different behavior.
        */
       boolean isEmpty();
  
      /**
       * Gets a string representation of the adapter data that can help
       * {@link android.service.autofill.AutofillService} autofill the view backed by the adapter.
       *
       * <p>
       * It should only be set (i.e., non-{@code null} if the values do not represent PII
       * (Personally Identifiable Information - sensitive data such as email addresses,
       * credit card numbers, passwords, etc...). For
       * example, it's ok to return a list of month names, but not a list of usernames. A good rule of
       * thumb is that if the adapter data comes from static resources, such data is not PII - see
       * {@link android.view.ViewStructure#setDataIsSensitive(boolean)} for more info.
       *
       * @return {@code null} by default, unless implementations override it.
       */
      default @Nullable CharSequence[] getAutofillOptions() {
          return null;
      }
  }
  