152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project/* 252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * Copyright (C) 2008 The Android Open Source Project 352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * 452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * Licensed under the Apache License, Version 2.0 (the "License"); 552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * you may not use this file except in compliance with the License. 652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * You may obtain a copy of the License at 752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * 852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * http://www.apache.org/licenses/LICENSE-2.0 952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * 1052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * Unless required by applicable law or agreed to in writing, software 1152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * distributed under the License is distributed on an "AS IS" BASIS, 1252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 1352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * See the License for the specific language governing permissions and 1452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * limitations under the License. 1552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project */ 1652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 1752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectpackage com.example.android.apis.view; 1852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 1952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.app.ListActivity; 2052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.content.Context; 2152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.os.Bundle; 2252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.view.LayoutInflater; 2352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.view.View; 2452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.view.ViewGroup; 2552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.widget.BaseAdapter; 2652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.widget.TextView; 2752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.widget.ImageView; 2852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.graphics.BitmapFactory; 2952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport android.graphics.Bitmap; 3052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectimport com.example.android.apis.R; 3152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 3252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project/** 3352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * Demonstrates how to write an efficient list adapter. The adapter used in this example binds 3452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * to an ImageView and to a TextView for each row in the list. 3552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * 3652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * To work efficiently the adapter implemented here uses two techniques: 3752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * - It reuses the convertView passed to getView() to avoid inflating View when it is not necessary 3852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * - It uses the ViewHolder pattern to avoid calling findViewById() when it is not necessary 3952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * 4052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * The ViewHolder pattern consists in storing a data structure in the tag of the view returned by 4152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * getView(). This data structures contains references to the views we want to bind data to, thus 4252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * avoiding calls to findViewById() every time getView() is invoked. 4352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project */ 4452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Projectpublic class List14 extends ListActivity { 4552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 4652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project private static class EfficientAdapter extends BaseAdapter { 4752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project private LayoutInflater mInflater; 4852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project private Bitmap mIcon1; 4952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project private Bitmap mIcon2; 5052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 5152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project public EfficientAdapter(Context context) { 5252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // Cache the LayoutInflate to avoid asking for a new one each time. 5352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project mInflater = LayoutInflater.from(context); 5452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 5552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // Icons bound to the rows. 5652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project mIcon1 = BitmapFactory.decodeResource(context.getResources(), R.drawable.icon48x48_1); 5752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project mIcon2 = BitmapFactory.decodeResource(context.getResources(), R.drawable.icon48x48_2); 5852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project } 5952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 6052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project /** 6152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * The number of items in the list is determined by the number of speeches 6252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * in our array. 6352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * 6452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * @see android.widget.ListAdapter#getCount() 6552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project */ 6652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project public int getCount() { 6752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project return DATA.length; 6852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project } 6952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 7052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project /** 7152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * Since the data comes from an array, just returning the index is 7252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * sufficent to get at the data. If we were using a more complex data 7352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * structure, we would return whatever object represents one row in the 7452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * list. 7552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * 7652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * @see android.widget.ListAdapter#getItem(int) 7752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project */ 7852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project public Object getItem(int position) { 7952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project return position; 8052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project } 8152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 8252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project /** 8352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * Use the array index as a unique id. 8452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * 8552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * @see android.widget.ListAdapter#getItemId(int) 8652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project */ 8752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project public long getItemId(int position) { 8852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project return position; 8952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project } 9052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 9152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project /** 9252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * Make a view to hold each row. 9352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * 9452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * @see android.widget.ListAdapter#getView(int, android.view.View, 9552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project * android.view.ViewGroup) 9652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project */ 9752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project public View getView(int position, View convertView, ViewGroup parent) { 9852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // A ViewHolder keeps references to children views to avoid unneccessary calls 9952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // to findViewById() on each row. 10052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project ViewHolder holder; 10152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 10252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // When convertView is not null, we can reuse it directly, there is no need 10352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // to reinflate it. We only inflate a new View when the convertView supplied 10452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // by ListView is null. 10552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project if (convertView == null) { 10652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project convertView = mInflater.inflate(R.layout.list_item_icon_text, null); 10752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 10852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // Creates a ViewHolder and store references to the two children views 10952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // we want to bind data to. 11052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project holder = new ViewHolder(); 11152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project holder.text = (TextView) convertView.findViewById(R.id.text); 11252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project holder.icon = (ImageView) convertView.findViewById(R.id.icon); 11352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 11452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project convertView.setTag(holder); 11552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project } else { 11652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // Get the ViewHolder back to get fast access to the TextView 11752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // and the ImageView. 11852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project holder = (ViewHolder) convertView.getTag(); 11952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project } 12052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 12152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project // Bind the data efficiently with the holder. 12252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project holder.text.setText(DATA[position]); 12352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project holder.icon.setImageBitmap((position & 1) == 1 ? mIcon1 : mIcon2); 12452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 12552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project return convertView; 12652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project } 12752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 12852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project static class ViewHolder { 12952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project TextView text; 13052d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project ImageView icon; 13152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project } 13252d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project } 13352d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 13452d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project @Override 13552d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project public void onCreate(Bundle savedInstanceState) { 13652d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project super.onCreate(savedInstanceState); 13752d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project setListAdapter(new EfficientAdapter(this)); 13852d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project } 13952d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project 140b39c4ba316a523e4ecf0ac9e71377b8c5b35c25cJeff Brown private static final String[] DATA = Cheeses.sCheeseStrings; 14152d4c30ca52320ec92d1d1ddc8db3f07f69c4f98The Android Open Source Project} 142