自动刷新活动。

    public void onCreate(Bundle savedInstanceState)  
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    this.mHandler = new Handler();

    this.mHandler.postDelayed(m_Runnable,5000);


}//onCreate

private final Runnable m_Runnable = new Runnable()
{
    public void run()

    {
        Toast.makeText(refresh.this,\"in runnable\",Toast.LENGTH_SHORT).show();

        refresh.this.mHandler.postDelayed(m_Runnable, 5000);            
    }

};//runnable

Handler handler = new Handler();
Runnable refresh;

refresh = new Runnable() {
    public void run() {
        // Do something
        handler.postDelayed(refresh, 5000);
    }
};
handler.post(refresh);

public class MainActivity extends Activity {
Handler mHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
        this.mHandler = new Handler();
        m_Runnable.run();

}
    private final Runnable m_Runnable = new Runnable()
    {
        public void run()

        {
            Toast.makeText(MainActivity.this,\"in runnable\",Toast.LENGTH_SHORT).show();

            MainActivity.this.mHandler.postDelayed(m_Runnable,20000);            
        }

    };
}

AlarmManager