Android Open Source - mvfa Merge Adapter

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License

The source code is released under:

GNU General Public License

Java Source Code

/***
  Copyright (c) 2008-2009 CommonsWare, LLC
  Portions (c) 2009 Google, Inc./*w  ww.  ja  v  a 2 s.  c  o  m*/
  
  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 com.commonsware.cwac.merge;

import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListAdapter;
import java.util.ArrayList;
import java.util.List;
import com.commonsware.cwac.sacklist.SackOfViewsAdapter;

/**
 * Adapter that merges multiple child adapters and views into a single
 * contiguous whole.
 * 
 * Adapters used as pieces within MergeAdapter must have view type IDs
 * monotonically increasing from 0. Ideally, adapters also have distinct ranges
 * for their row ids, as returned by getItemId().
 * 
 */
public class MergeAdapter extends BaseAdapter
  {
  private ArrayList<ListAdapter> pieces = new ArrayList<ListAdapter>();

  /**
   * Stock constructor, simply chaining to the superclass.
   */
  public MergeAdapter()
    {
    super();
    }

  /**
   * Adds a new adapter to the roster of things to appear in the aggregate
   * list.
   * 
   * @param adapter
   *            Source for row views for this section
   */
  public void addAdapter(ListAdapter adapter)
    {
    pieces.add(adapter);
    }

  /**
   * Adds a new View to the roster of things to appear in the aggregate list.
   * 
   * @param view
   *            Single view to add
   */
  public void addView(View view)
    {
    ArrayList<View> list = new ArrayList<View>(1);

    list.add(view);

    addViews(list);
    }

  /**
   * Adds a list of views to the roster of things to appear in the aggregate
   * list.
   * 
   * @param views
   *            List of views to add
   */
  public void addViews(List<View> views)
    {
    pieces.add(new SackOfViewsAdapter(views));
    }

  /**
   * Get the data item associated with the specified position in the data set.
   * 
   * @param position
   *            Position of the item whose data we want
   */
  @Override
  public Object getItem(int position)
    {
    for(ListAdapter piece : pieces)
      {
      int size = piece.getCount();

      if(position < size)
        {
        return (piece.getItem(position));
        }

      position -= size;
      }

    return (null);
    }

  /**
   * How many items are in the data set represented by this Adapter.
   */
  @Override
  public int getCount()
    {
    int total = 0;

    for(ListAdapter piece : pieces)
      {
      total += piece.getCount();
      }

    return (total);
    }

  /**
   * Returns the number of types of Views that will be created by getView().
   */
  @Override
  public int getViewTypeCount()
    {
    int total = 0;

    for(ListAdapter piece : pieces)
      {
      total += piece.getViewTypeCount();
      }

    return (Math.max(total, 1)); // needed for setListAdapter() before
                    // content add'
    }

  /**
   * Get the type of View that will be created by getView() for the specified
   * item.
   * 
   * @param position
   *            Position of the item whose data we want
   */
  @Override
  public int getItemViewType(int position)
    {
    int typeOffset = 0;
    int result = -1;

    for(ListAdapter piece : pieces)
      {
      int size = piece.getCount();

      if(position < size)
        {
        result = typeOffset + piece.getItemViewType(position);
        break;
        }

      position -= size;
      typeOffset += piece.getViewTypeCount();
      }

    return (result);
    }

  /**
   * Are all items in this ListAdapter enabled? If yes it means all items are
   * selectable and clickable.
   */
  @Override
  public boolean areAllItemsEnabled()
    {
    return (false);
    }

  /**
   * Returns true if the item at the specified position is not a separator.
   * 
   * @param position
   *            Position of the item whose data we want
   */
  @Override
  public boolean isEnabled(int position)
    {
    for(ListAdapter piece : pieces)
      {
      int size = piece.getCount();

      if(position < size)
        {
        return (piece.isEnabled(position));
        }

      position -= size;
      }

    return (false);
    }

  /**
   * Get a View that displays the data at the specified position in the data
   * set.
   * 
   * @param position
   *            Position of the item whose data we want
   * @param convertView
   *            View to recycle, if not null
   * @param parent
   *            ViewGroup containing the returned View
   */
  @Override
  public View getView(int position, View convertView, ViewGroup parent)
    {
    for(ListAdapter piece : pieces)
      {
      int size = piece.getCount();

      if(position < size)
        {

        return (piece.getView(position, convertView, parent));
        }

      position -= size;
      }

    return (null);
    }

  /**
   * Get the row id associated with the specified position in the list.
   * 
   * @param position
   *            Position of the item whose data we want
   */
  @Override
  public long getItemId(int position)
    {
    for(ListAdapter piece : pieces)
      {
      int size = piece.getCount();

      if(position < size)
        {
        return (piece.getItemId(position));
        }

      position -= size;
      }

    return (-1);
    }
  }

Java Source Code List

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