SingleTypeAdapter.java

/*
 * Copyright 2012 Kevin Sawicki <kevinsawicki@gmail.com>
 *
 * 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.campus.prime.ui;

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import java.util.Arrays;
import java.util.Collection;
import java.util.List;



/**
 * Adapter for lists where only a single view type is used
 *
 * @param <V>
 */
public abstract class SingleTypeAdapter<V> extends TypeAdapter {

  private static final Object[] EMPTY = new Object[0];

  private final LayoutInflater inflater;

  private final int layout;

  private final int[] children;

  private Object[] items;

  protected Context context;
  
  /**
   * Create adapter
   *
   * @param activity
   * @param layoutResourceId
   */
  public SingleTypeAdapter(final Activity activity, final int layoutResourceId) {
    this(activity.getLayoutInflater(), layoutResourceId);
  }

  /**
   * Create adapter
   *
   * @param context
   * @param layoutResourceId
   */
  public SingleTypeAdapter(final Context context, final int layoutResourceId) {
	
    this(LayoutInflater.from(context), layoutResourceId);
  }

  /**
   * Create adapter
   *
   * @param inflater
   * @param layoutResourceId
   */
  public SingleTypeAdapter(final LayoutInflater inflater,
      final int layoutResourceId) {
    this.inflater = inflater;
    this.layout = layoutResourceId;

    items = EMPTY;

    int[] childIds = getChildViewIds();
    if (childIds == null)
      childIds = new int[0];
    children = childIds;
  }

  /**
   * Get a list of all items
   *
   * @return list of all items
   */
  @SuppressWarnings("unchecked")
  protected List<V> getItems() {
    List<? extends Object> objList = Arrays.asList(items);
    return (List<V>) objList;
  }

  /**
   * Set items to display
   *
   * @param items
   */
  public void setItems(final Collection<?> items) {
    if (items != null && !items.isEmpty())
      setItems(items.toArray());
    else
      setItems(EMPTY);
  }

  /**
   * Set items to display
   *
   * @param items
   */
  public void setItems(final Object[] items) {
    if (items != null)
      this.items = items;
    else
      this.items = EMPTY;
    notifyDataSetChanged();
  }

  @Override
  public int getCount() {
    return items.length;
  }

  @SuppressWarnings("unchecked")
  public V getItem(final int position) {
    return (V) items[position];
  }

  @Override
  public long getItemId(final int position) {
    return items[position].hashCode();
  }

  /**
   * Get child view ids to store
   * <p>
   * The index of each id in the returned array should be used when using the
   * helpers to update a specific child view
   *
   * @return ids
   */
  protected abstract int[] getChildViewIds();

  /**
   * Initialize view
   *
   * @param view
   * @return view
   */
  protected View initialize(final View view) {
    return super.initialize(view, children);
  }

  /**
   * Update view for item
   *
   * @param position
   * @param view
   * @param item
   */
  protected void update(int position, View view, V item) {
    setCurrentView(view);
    update(position, item);
  }

  /**
   * Update item
   *
   * @param position
   * @param item
   */
  protected abstract void update(int position, V item);

  @Override
  public View getView(final int position, View convertView,
      final ViewGroup parent) {
    if (convertView == null)
      convertView = initialize(inflater.inflate(layout, null));
    update(position, convertView, getItem(position));
    return convertView;
  }
}