Question

我想启动一个计数器2分钟，当活动销毁时，我想保存该计数器，然后在活动恢复时我想在我离开的地方启动计数器

counter = new CountDownTimer(120000, 1000) { // adjust the milli seconds here

        public void onTick(long millisUntilFinished)
        {
            textview.setText("" + String.format("%d min, %d sec",
                    TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished),
                    TimeUnit.MILLISECONDS.toSeconds(millisUntilFinished) -
                            TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished))));

            Log.i(TAG, "onTick: "+millisUntilFinished);
        }

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

Answer 1

当活动被销毁时，我们只保存一个millisUntilFinished的值，并在活动再次开始时使用该值创建一个新的CountDownTimer。

long millisUntilFinished;

在onDestroy()（或onStop()）中

@Override
    public void onDestroy() {
        SharedPreferences.Editor editor = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE).edit();
        editor.putLong("millisUntilFinished", millisUntilFinished);
        editor.apply();
        super.onDestroy();
    }

并在要启动millisUntilFinished时获得CountDownTimer的值

        SharedPreferences prefs = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE);
        millisUntilFinished = prefs.getLong("millisUntilFinished", 120000);

        counter = new CountDownTimer(millisUntilFinished, 1000) { // adjust the milli seconds here

            public void onTick(long millisUntilFinished) {
                this.millisUntilFinished = millisUntilFinished;
                textview.setText("" + String.format("%d min, %d sec",
                        TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished),
                        TimeUnit.MILLISECONDS.toSeconds(millisUntilFinished)
                                - TimeUnit.MINUTES.toSeconds(
                                TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished))));

                Log.i(TAG, "onTick: " + millisUntilFinished);
            }

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

Answer 2

由于无法始终保证onStop以onDestroy()方法将计数器数据存储在共享首选项中，请使用onResume方法存储的数据来启动计数器

在活动销毁时保存Countdowntimer，并在onResume（）中恢复它

2 个答案: