我想按下START按钮开始重复两行代码,然后按下按钮STOP.我尝试使用TimerTask和Handles,但无法弄清楚如何.
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//final int i;
final TextView textView = (TextView) findViewById(R.id.textView);
final Button START_STOP = (Button) findViewById(R.id.START_STOP);
final ImageView random_note = (ImageView) findViewById(R.id.random_note);
final int min = 0;
final int max = 2;
final Integer[] image = { R.drawable.a0,R.drawable.a1,R.drawable.a2 };
START_STOP.setTag(1);
START_STOP.setText("START");
START_STOP.setonClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int status = (Integer) v.getTag();
if (status ==1) {
textView.setText("Hello");
START_STOP.setText("STOP");
v.setTag(0);
final Random random = new Random();
//************************************************************
// I would like to loop next 2 lines of code every 5 seconds.//
int i = random.nextInt(2 - 0 + 1) + 0;
random_note.setimageResource(image[i]);
//************************************************************
}
else
{
textView.setText("Bye");
START_STOP.setText("Let's PLAY!");
v.setTag(1);
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main,menu);
return true;
}
}
解决方法
在其中一个答案中使用CountDownTimer是一种方法.另一种方法是使用Handler和
postDelayed方法：
private boolean started = false;
private Handler handler = new Handler();
private Runnable runnable = new Runnable() {
@Override
public void run() {
final Random random = new Random();
int i = random.nextInt(2 - 0 + 1) + 0;
random_note.setimageResource(image[i]);
if(started) {
start();
}
}
};
public void stop() {
started = false;
handler.removeCallbacks(runnable);
}
public void start() {
started = true;
handler.postDelayed(runnable,2000);
}
以下是使用Timer和TimerTask的示例：
private Timer timer;
private TimerTask timerTask = new TimerTask() {
@Override
public void run() {
final Random random = new Random();
int i = random.nextInt(2 - 0 + 1) + 0;
random_note.setimageResource(image[i]);
}
};
public void start() {
if(timer != null) {
return;
}
timer = new Timer();
timer.scheduleAtFixedrate(timerTask,2000);
}
public void stop() {
timer.cancel();
timer = null;
}