如何知道我何时关闭应用程序？

Question

My question is simple, I tried disable the bluetooth for my app when the user close the app. I need that if the user is with the app in background, the bluetooth maintain active, but if the user slide the app out of screen, the bluetooth closes.

I know how disable the bluetooth.

if (mBluetoothAdapter.isEnabled()){
    mBluetoothAdapter.disable();
}

Works perfectly, but I need call that 3 lines when the user close the app, I tried with onDestroy , onPause , onStop , but noone works for me.

onDestroy method is called when the user touch back button and the task go for background. onPause method is called when the user touch the recents button, but the app is not closed. onStop method same of onPause .

So... How to know when the user close the app?

Thank you

Answer 1

You can write a method to check if the app is running in background or not.

private boolean isAppIsInBackground(Context context) {
        isInBackground = true;
        ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.KITKAT_WATCH) {
            List<ActivityManager.RunningAppProcessInfo> runningProcesses = am.getRunningAppProcesses();
            for (ActivityManager.RunningAppProcessInfo processInfo : runningProcesses) {
                if (processInfo.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                    for (String activeProcess : processInfo.pkgList) {
                        if (activeProcess.equals(context.getPackageName())) {

                            isInBackground = false;
                        }
                    }
                }
            }
        } else {
            List<ActivityManager.RunningTaskInfo> taskInfo = am.getRunningTasks(1);
            ComponentName componentInfo = taskInfo.get(0).topActivity;
            if (componentInfo.getPackageName().equals(context.getPackageName())) {
                isInBackground = false;

            }
        }

        return isInBackground;
    }

This method returns true if the app is running in background.Then you can enable or disable bluetooth accordingly. Also you can set a flag in your onResume and onPause methods of the BaseActivity which is extended by all other activitues so that you can check the flags to know whether app is running or not.

Answer 2

Make a BaseActivity and override its OnPause() method and extend every Activity from BaseActivity .

I would also like to mention that onPause() is fired even when switching between multiple activities, so you'd need to track when it's pausing to go to another screen.

Reference : http://developer.android.com/reference/android/app/Activity.html#ActivityLifecycle

Answer 3

如果要在用户退出活动时禁用蓝牙，请在onBackPressed()其禁用。