[转]notifyDataSetChanged() 动态更新ListView

有时候我们需要修改已经生成的列表，添加或者修改数据，notifyDataSetChanged()可以在修改适配器绑定的数组后，不用重新刷新Activity，通知Activity更新ListView。今天的例子就是通过Handler AsyncTask两种方式来动态更新ListView.
布局main.xml:

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:orientation="vertical"
 4     android:layout_width="fill_parent"
 5     android:layout_height="fill_parent"
 6     >
 7 <ListView  android:id="@+id/lv"
 8     android:layout_width="fill_parent"
 9     android:layout_height="wrap_content"
10     android:text="@string/hello"
11     />
12 </LinearLayout>

ListView列表布局playlist.xml:

1 <?xml version="1.0" encoding="utf-8"?>
2 <TextView
3   android:id="@+id/text1"
4   xmlns:android="http://schemas.android.com/apk/res/android"
5   android:layout_width="fill_parent"
6   android:layout_height="30px"
7   android:textSize="18sp"
8 ></TextView>

程序代码：

 1 import java.util.ArrayList;
 2
 3  import android.app.Activity;
 4  import android.os.AsyncTask;
 5  import android.os.Bundle;
 6  import android.os.Handler;
 7  import android.view.View;
 8  import android.widget.AdapterView;
 9 import android.widget.ArrayAdapter;
10 import android.widget.ListView;
11 import android.widget.AdapterView.OnItemClickListener;
12
13 public class main extends Activity {
14     /** Called when the activity is first created. */
15     ListView lv;
16     ArrayAdapter<String> Adapter;
17     ArrayList<String> arr=new ArrayList<String>();
18     @Override
19     public void onCreate(Bundle savedInstanceState) {
20         super.onCreate(savedInstanceState);
21         setContentView(R.layout.main);
22         lv=(ListView)findViewById(R.id.lv);
23         arr.add("123");
24         arr.add("234");
25         arr.add("345");
26         Adapter = new ArrayAdapter<String>(this,R.layout.playlist, arr);
27         lv.setAdapter(Adapter);
28         lv.setOnItemClickListener(lvLis);
29         editItem edit= new editItem();
30         edit.execute("0","第1项");//把第一项内容改为"第一项"
31         Handler handler=new Handler();
32         handler.postDelayed(add,3000);//延迟3秒执行
33     }
34     Runnable add=new Runnable(){
35
36         @Override
37         public void run() {
38             // TODO Auto-generated method stub
39             arr.add("增加一项");//增加一项
40             Adapter.notifyDataSetChanged();
41         }
42     };
43     class editItem extends AsyncTask<String,Integer,String>{
44         @Override
45         protected String doInBackground(String... params) {
46                 arr.set(Integer.parseInt(params[0]),params[1]);
47                 //params得到的是一个数组，params[0]在这里是"0",params[1]是"第1项"
48                 //Adapter.notifyDataSetChanged();
49                 //执行添加后不能调用 Adapter.notifyDataSetChanged()更新UI，因为与UI不是同线程
50                 //下面的onPostExecute方法会在doBackground执行后由UI线程调用
51             return null;
52         }
53
54         @Override
55         protected void onPostExecute(String result) {
56             // TODO Auto-generated method stub
57             super.onPostExecute(result);
58             Adapter.notifyDataSetChanged();
59             //执行完毕，更新UI
60         }
61
62     }
63     private OnItemClickListener lvLis=new OnItemClickListener(){
64         @Override
65         public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
66                 long arg3) {
67             //点击条目时触发
68             //arg2即为点中项的位置
69             setTitle(String.valueOf(arr.get(arg2)));
70
71         }
72
73     };
74
75 }