[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:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<ListView  android:id="@+id/lv"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
</LinearLayout>

ListView列表布局playlist.xml:

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

程序代码：

import java.util.ArrayList;
 
 import android.app.Activity;
 import android.os.AsyncTask;
 import android.os.Bundle;
 import android.os.Handler;
 import android.view.View;
 import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.AdapterView.OnItemClickListener;
 
public class main extends Activity {
    /** Called when the activity is first created. */
    ListView lv;
    ArrayAdapter<String> Adapter;
    ArrayList<String> arr=new ArrayList<String>();
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        lv=(ListView)findViewById(R.id.lv);
        arr.add("123");
        arr.add("234");
        arr.add("345");
        Adapter = new ArrayAdapter<String>(this,R.layout.playlist, arr);
        lv.setAdapter(Adapter);
        lv.setOnItemClickListener(lvLis); 
        editItem edit= new editItem();
        edit.execute("0","第1项");//把第一项内容改为"第一项"
        Handler handler=new Handler();
        handler.postDelayed(add,3000);//延迟3秒执行
    }
    Runnable add=new Runnable(){
 
        @Override
        public void run() {
            // TODO Auto-generated method stub
            arr.add("增加一项");//增加一项
            Adapter.notifyDataSetChanged();    
        }       
    };
    class editItem extends AsyncTask<String,Integer,String>{
        @Override
        protected String doInBackground(String... params) {
                arr.set(Integer.parseInt(params[0]),params[1]);
                //params得到的是一个数组，params[0]在这里是"0",params[1]是"第1项"
                //Adapter.notifyDataSetChanged();
                //执行添加后不能调用 Adapter.notifyDataSetChanged()更新UI，因为与UI不是同线程
                //下面的onPostExecute方法会在doBackground执行后由UI线程调用
            return null;    
        }
 
        @Override
        protected void onPostExecute(String result) {
            // TODO Auto-generated method stub
            super.onPostExecute(result);
            Adapter.notifyDataSetChanged();
            //执行完毕，更新UI
        }
 
    }
    private OnItemClickListener lvLis=new OnItemClickListener(){
        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {
            //点击条目时触发
            //arg2即为点中项的位置
            setTitle(String.valueOf(arr.get(arg2)));
 
        }
 
    };
 
}