曾经倒计时使用Timer和TimerTask来处理

private Timer timer = new Timer();

private long time;

TimerTask timerTask = new TimerTask() {

@Override

public void run() {

time = time - 1000;

//TODO something

//通过handler发送消息更改界面

}

};

//普通的使用方式

Handler handler = new Handler() {

@Override

public void handleMessage(Message msg) {

super.handleMessage(msg);

mTimeTv.setText("");

}

}

};

但是多线程并行处理定时任务时，Timer运行多个TimeTask时，只要其中之一没有捕获抛出的异常，其它任务便会自动终止运行。

替换方法：使用ScheduledExecutorService

private long time;

private ScheduledExecutorService timeService = new ScheduledThreadPoolExecutor(1, new ThreadPoolExecutor.AbortPolicy());

timeService.scheduleAtFixedRate(new Runnable() {

@Override

public void run() {

time = time - 1000;

handler.sendEmptyMessage(0);

}

}, initialDelay, period, TimeUnit unit);

initialDelay：the time to delay first execution

period ：the period between successive executions

TimeUnit unit ：the time unit of the initialDelay and period parameters

TimeUnit.DAYS //天

TimeUnit.HOURS //小时

TimeUnit.MINUTES //分钟

TimeUnit.SECONDS //秒

TimeUnit.MILLISECONDS //毫秒

//Handler正确使用方式，防止内存泄漏

static class MyHandler extends Handler {

private WeakReference mWeakReference;

private ScheduledExecutorService timeService;

private MyHandler(WeakReference mWeakReference) {

this.mWeakReference = mWeakReference;

timeService = mWeakReference.get().timeService;

}

@Override

public void handleMessage(Message msg) {

super.handleMessage(msg);

mWeakReference.get().updateText();

}

}

注：不能在handler里面直接调用mWeakReference.get().mTimeTv.setText("");

会抛异常：android.view.ViewRoot$CalledFromWrongThreadException

在activity里提出方法

/**

* handler调用更新界面

*/

private void updateText() {

mTimeTv.setText(getString(R.string.order_time02_task, d, h, m, s));

}

然后在不需要计时器的时候调用

@Override

protected void onDestroy() {

super.onDestroy();

//释放资源

if (timeService != null && !timeService.isShutdown()) {

timeService.shutdown();

}

}