如果用户在活动过程中退出应用程序，然后重新启动应用程序，则应用程序将崩溃

Question

我有一个名为"OtpVerification"的活动，其中包含 30 秒的计时器，在此过程中，如果我退出应用程序然后重新打开应用程序，它会产生问题 1）几秒钟后，当我重新打开应用程序时，应用程序从 MainActivity 启动而不是该活动和 2） 应用程序崩溃。

这是场景：

-场景：当自动 OTP 验证过程开始时启动 30 秒计时器，现在用户尝试通过按返回按钮结束此过程并退出应用程序，然后他立即在几秒钟内重新启动应用程序。现在，随着计时器过期并且应用程序尝试启动手动 OTP 验证屏幕，这将创建一个致命的异常，应用程序崩溃。

这是代码：-

@SuppressLint("SetTextI18n")
private void init() {// initialize view controls
    //Initialize a new CountDownTimer instance
    long m_MillisInFuture = 30000;// timer value
    long m_CountDownInterval = 1000;// timer break up
    m_oTimer = new CountDownTimer(m_MillisInFuture, m_CountDownInterval) {
        public void onTick(long millisUntilFinished) {
            @SuppressWarnings("UnusedAssignment") long millis = millisUntilFinished;
            @SuppressLint("DefaultLocale") String hms = String.format("%02d:%02d", TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished),
                    TimeUnit.MILLISECONDS.toSeconds(millisUntilFinished) -
                            TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished)));
            System.out.println(hms);
            tv.setText(hms);
            //Another one second passed
            //Each second ProgressBar progress counter added one
            m_n_ProgressStatus += 1;
            m_timerProgress.setProgress(m_n_ProgressStatus);
        }
        public void onFinish() {// when timer finished
            /*This is new change ....check if app is in backround or foreground*/
            /*if app is in background*/
            if (NetworkUtil.isAppIsInBackground(getApplicationContext())) {
                System.out.println("In Background");
                /*if app is in background start service */
                Intent startService = new Intent(getApplicationContext(), OTPIntentService.class); // if condition match then start service to notify server regarding app installation
                getApplicationContext().startService(startService);// start service
            } else {
                System.out.println("In Foreground");
                /*if app is in forground than send request to server*/
                verifyOTP();
            }

        }
    }.start();// start timer
    // retreive progress bar count........
    int progressBarMaximumValue = (int) (m_MillisInFuture / m_CountDownInterval);
    //Set ProgressBar maximum value
    //ProgressBar range (0 to maximum value)
    m_timerProgress.setMax(progressBarMaximumValue);
    //Display the CountDownTimer initial value
    tv.setText(progressBarMaximumValue + "Seconds...");
}
@Override
public void onDestroy() {// unregister broadcast receiver ........
    super.onDestroy();
    getApplicationContext().unregisterReceiver(m_oOtpReceiver);// unregistaer broadcast receiver.
}

Answer 1

尝试在onPause（）中取消注册您的接收器，并在onResume（）中创建并将标志更改为false，然后在onResume（）中检查标志是否为假，然后再次重新注册接收器。我的应用程序中遇到了类似的问题，这些确实帮助了我。

Answer 2

有点像我在应用程序中实现的，我从我的服务中调用了接收器

@Override
protected void onResume() {
    super.onResume();
    registerReceiver();
}
@Override
protected void onPause() {
    LocalBroadcastManager.getInstance(this).unregisterReceiver(mRegistrationBroadcastReceiver);
    isReceiverRegistered = false;
    super.onPause();
}
private void registerReceiver(){
    if(!isReceiverRegistered) {
        LocalBroadcastManager.getInstance(this).registerReceiver(mRegistrationBroadcastReceiver,
                new IntentFilter(SessionStore.REGISTRATION_COMPLETE));
        isReceiverRegistered = true;
    }
}