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("");
arr.add("");
arr.add("");
Adapter = new ArrayAdapter<String>(this,R.layout.playlist, arr);
lv.setAdapter(Adapter);
lv.setOnItemClickListener(lvLis);
editItem edit= new editItem();
edit.execute("","第1项");//把第一项内容改为"第一项"
Handler handler=new Handler();
handler.postDelayed(add,);//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[]),params[]);
//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))); } }; }