public class MainActivity extends Activity {    ImageView imageView1;    int index=0;        int[] pics=new int[]{R.drawable.pic1,R.drawable.pic2,R.drawable.pic3};        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                imageView1=(ImageView)findViewById(R.id.imageView1);                thread.start();        }        Thread thread=new Thread(){        public void run() {            try {                while(true){                    sleep(1000);                    hand.sendEmptyMessage(12345);                }            } catch (InterruptedException e) {                // TODO 自动生成的 catch 块                e.printStackTrace();            }        }    };    Handler hand=new Handler(){        public void handleMessage(Message msg) {            if(msg.what==12345){                imageView1.setImageResource(pics[index%3]);                                index=index+1;            }        }    };    }