Question

我有一个CountDownTimer，它需要一直运行。有2项活动（A和B）。 Activity A具有CountDownTimer，它更新其中的TextView。当我切换到B时，CountDownTimer仍然运行（这是所需的行为），但当我切换回A时，似乎有一个旧的和新的A.计时器不会更新“新”内的TextView A.首次访问A时，它仅启动一次。有关如何解决这个问题的任何想法？也许把计时器放在其他地方？修改：部分代码：

private void prepareTimer() {
    // TODO: DOES NOT WORK YET! (switching activities -> runs in old activity)
    textTime = (TextView) findViewById(R.id.text_time); // is a field

    if (!timerRunning) {
        timerRunning = true;

        int duration = 60000;
        timer = new CountDownTimer(duration, 1000) {

            public void onTick(long millisUntilFinished) {
                long minsLeft = (long) Math.floor((double) millisUntilFinished / (double) Constants.ONE_MINUTE) + 1;
                textTime.setText(minsLeft + " Min.");
            }

            public void onFinish() {
                textTime.setText("done!");
            }
        };
        timer.start();
    }
}

Answer 1

CDT正在自己独立的线程中运行。您尝试访问的TextView引用，CDT不再可用（因为您在B中时不再显示您的活动A）尝试创建TextView的新引用返回A时，CDT线程仍在运行，无论您是从A移动到B还是反之。我希望这将有所帮助。确保在UI线程中进行更改。 ;）

编辑：

private void prepareTimer() {
    // TODO: DOES NOT WORK YET! (switching activities -> runs in old activity)
    textTime = (TextView) findViewById(R.id.text_time); // is a field

    if (!timerRunning) {
        timerRunning = true;

        int duration = 60000;
        timer = new CountDownTimer(duration, 1000) {

            public void onTick(long millisUntilFinished) {
                long minsLeft = (long) Math.floor((double) millisUntilFinished / (double) Constants.ONE_MINUTE) + 1;
                textTime.setText(minsLeft + " Min.");
            }

            public void onFinish() {
                textTime.setText("done!");
            }
        };
        timer.start();
    }
    else
    {
     textTime = (TextView) findViewById(R.id.text_time);
    }

}

切换活动时，CountDownTimer在旧的Activity中运行

1 个答案: