1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.example.android.listviewanimations; 18 19 import java.util.ArrayList; 20 import java.util.HashMap; 21 import java.util.List; 22 23 import android.animation.Animator; 24 import android.animation.AnimatorListenerAdapter; 25 import android.animation.ObjectAnimator; 26 import android.app.Activity; 27 import android.content.Context; 28 import android.os.Bundle; 29 import android.view.View; 30 import android.widget.AdapterView; 31 import android.widget.ArrayAdapter; 32 import android.widget.CheckBox; 33 import android.widget.ListView; 34 35 /** 36 * This example shows how animating ListView items can lead to problems as views are recycled, 37 * and how to perform these types of animations correctly with new API added in Jellybean. 38 * 39 * Watch the associated video for this demo on the DevBytes channel of developer.android.com 40 * or on YouTube at https://www.youtube.com/watch?v=8MIfSxgsHIs. 41 */ 42 public class ListViewAnimations extends Activity { 43 44 @Override 45 protected void onCreate(Bundle savedInstanceState) { 46 super.onCreate(savedInstanceState); 47 setContentView(R.layout.activity_list_view_animations); 48 49 final CheckBox vpaCB = (CheckBox) findViewById(R.id.vpaCB); 50 final CheckBox setTransientStateCB = (CheckBox) findViewById(R.id.setTransientStateCB); 51 final ListView listview = (ListView) findViewById(R.id.listview); 52 final ArrayList<String> cheeseList = new ArrayList<String>(); 53 for (int i = 0; i < Cheeses.sCheeseStrings.length; ++i) { 54 cheeseList.add(Cheeses.sCheeseStrings[i]); 55 } 56 final StableArrayAdapter adapter = new StableArrayAdapter(this, 57 android.R.layout.simple_list_item_1, cheeseList); 58 listview.setAdapter(adapter); 59 60 listview.setOnItemClickListener(new AdapterView.OnItemClickListener() { 61 62 @Override 63 public void onItemClick(AdapterView<?> parent, final View view, int position, long id) { 64 final String item = (String) parent.getItemAtPosition(position); 65 if (vpaCB.isChecked()) { 66 view.animate().setDuration(1000).alpha(0). 67 withEndAction(new Runnable() { 68 @Override 69 public void run() { 70 cheeseList.remove(item); 71 adapter.notifyDataSetChanged(); 72 view.setAlpha(1); 73 } 74 }); 75 } else { 76 // Here's where the problem starts - this animation will animate a View object. 77 // But that View may get recycled if it is animated out of the container, 78 // and the animation will continue to fade a view that now contains unrelated 79 // content. 80 ObjectAnimator anim = ObjectAnimator.ofFloat(view, View.ALPHA, 0); 81 anim.setDuration(1000); 82 if (setTransientStateCB.isChecked()) { 83 // Here's the correct way to do this: if you tell a view that it has 84 // transientState, then ListView ill avoid recycling it until the 85 // transientState flag is reset. 86 // A different approach is to use ViewPropertyAnimator, which sets the 87 // transientState flag internally. 88 view.setHasTransientState(true); 89 } 90 anim.addListener(new AnimatorListenerAdapter() { 91 @Override 92 public void onAnimationEnd(Animator animation) { 93 cheeseList.remove(item); 94 adapter.notifyDataSetChanged(); 95 view.setAlpha(1); 96 if (setTransientStateCB.isChecked()) { 97 view.setHasTransientState(false); 98 } 99 } 100 }); 101 anim.start(); 102 103 } 104 } 105 106 }); 107 } 108 109 private class StableArrayAdapter extends ArrayAdapter<String> { 110 111 HashMap<String, Integer> mIdMap = new HashMap<String, Integer>(); 112 113 public StableArrayAdapter(Context context, int textViewResourceId, 114 List<String> objects) { 115 super(context, textViewResourceId, objects); 116 for (int i = 0; i < objects.size(); ++i) { 117 mIdMap.put(objects.get(i), i); 118 } 119 } 120 121 @Override 122 public long getItemId(int position) { 123 String item = getItem(position); 124 return mIdMap.get(item); 125 } 126 127 @Override 128 public boolean hasStableIds() { 129 return true; 130 } 131 132 } 133 134 } 135