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android: why onDestroy() is not invoked after finish()

There are two activities in my example, MainActiviy and EmptyActivity. In the MainActiviy, it create a notification, which target is the EmptyActivity. Well, EmptyActivity is very simple, just finish itself in its onCreate.
i added the trace in the MainActiviy's onDestroy and onBackPressed
I have invoked the finish() method in the onBackPress
The problem is:
open the application, and press back key, the log is printed in the logcat, means the MainActiviy's onDestroyed is invoked.
if open the application, and press the notification from the status bar, and then press back key, then no log in the onDestroy is printed
Strangely, if reopen the application, then the log in the onDestroy is printed..
Has anyone known why this happened. Thanks
i uploaded the example to the google drive
Test

why minus my question!!!
The link is different from mine !!
onDestroy() is called only when system is low on resources(memory, cpu time and so on) and makes a decision to kill your activity/application or when somebody calls finish() on your activity.
i have invoked finish() method!! My question is "why onDestroy() is not invoked after finish()"

Finish Theme.Transluscent.NoTitleBar?

I have an android activity with Theme=Theme.Transluscent.NoTitleBar.
I want to use finish this kind of activity using finish() but it doesnt work. As it is an invisible activity it goes to onPause State rather than onDestroy state.
How can I overcome this problem as it uses unnecessary memory.
Thank YOU !!

There are many threads which explain this. When you are calling finish(), Android will let your code in the specific block after the finish() call execute, and that is why the Toast message appears. A simple return statement after the finish() call is the solution. Taken from answer on question:
Android Help! I want to completely finish my activity, and after activity.finish no further code will execute?
Other relevant ones are:
Calling finish() on an Android activity doesn't actually finish
about finish() in android
Hope this helps.

you can use System.exit(0); but as stated it is not a good approach. but however you can use this approach to clear the previous activity intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
.

Subsequent Launch after uncalled onDestroy shows a blank screen

I am using a WebView in my app's sole Activity. Whenever the user clicks on the BACK button, I override the onKey and process some clean up before calling finish of the activity.
I see that once in a while (maybe 1 out of 20 times), onDestroy is not called. And in this case, if I launch my app again, a blank screen comes up. The Activity's onCreate is not called, and neither is my overridden Application's onCreate.
Does anyone know why this happens, and are there any possible solutions?
Thanks,
Rajath

Based on the little less than a line of code you have provided, please do the following:
Stop overriding back key.
Do the cleanup elsewhere, e.g., in onPause().

It turns out that I was capturing uncaught exceptions using the UncaughtExceptionHandler(). So, sometimes when the app was actually crashing in onDestroy(), the subsequent session was not properly launched.
Of course, in the case where the app's onDestroy() was not called at all, the problem is still fixed when I don't use UncaughtExceptionHandler(). Not sure why though.
-Rajath

What does this.finish() really do? Does it stop my code running?

I'm a bit hazy about what exactly this.finish() does. Specifically, I just wrote the following lines of code in an activity:
this.finish();
Globals gs = (Globals) getApplication();
gs.MainActivity.finish();
The code is meant to close the current activity and also close the core activity of the app. And it works great. However, I got wondering... obviously the current activity isn't quite ended after the first line is executed. And what if I was to call this.finish() and then start on some complicated computation?
My question is: When I call this.finish(), when exactly does my Activity get taken down?

Whatever method called finish() will run all the way through before the finish() method actually starts. So, to answer your question, after the calling method finishes then your activity will run its finish method.
If you don't want the method to continue then you can add a return statement after finish

I'm a bit hazy about what exactly this.finish() does
Calling finish() basically just notifies the Android OS that your activity is ready to be destroyed. Android will then (whenever its ready) call onPause() on the activity and proceed to destroy it (no guarentee onDestroy() will be called), via the activity lifecycle. In general, you probably should not be doing any more execution after you call finish(). According to the Android docs, you should call finish() when you are ready to close the activity.
when exactly does my Activity get taken down?
I am guessing your activity will simply be added to some destroy queue. During this time you might be able to continue executing until the OS destroys it. I believe you are for sure allowed to finish executing the method from which finish() was called.

Activity.finish() will not stop the current activity until the method is completely executed so to skip the remaining part of the code, you may use a return; use it with some condition to validate your skip.
if ( condition = true ) {
this.finish();
return;
}

Chris, I am no expert, but at the answer here about finish() in android is basically what codeMagic just said. The link is valuable because of the discussion regarding onStop() and onDestroy()

startActivity on Android

so i've been trying to get my application to run an Activity via an intent and it works fine, when i then assign the finish(); method, it returns to the activity that called it. The only thing i don't understand is that i'm not sure if the callee Activity is put onPause while the called Activity is in-front. I've tried to setup a toast message in the onPause() method of the callee Acitivty but it won't appear.
I first tried to call the second Activity with startActivity(intentname) and then a finish() method on the first Acitivty, i then tried to use the startActivityForResult() (even though i don't really need to recieve any information from the called Activity) method and closed it with onActivityResult().
I can't find any information about the side-effects that these Activity methods has on a Activity that's calling another. So i'm wondering if anybody could help me out ?
//Thx in advance

According to the documentation for Activity, the onPause() lifecycle method WILL be called when another Activity is put in front of it.
http://developer.android.com/reference/android/app/Activity.html#ActivityLifecycle
If the called Activity is is semi-transparent, then onStop() will also be called, but if your initial Activity is not visible at all, onStop() will not be called.
It is also of worth to note that when you call finish() on the called Activity, the onResume() will be called on the caller (and onStart(), assuming onStop() was also called)

To quickly answer your question: if activity A starts activity B, then A's onPause method is run. I think there might be an exception if B isn't full screen, but that's only a tentative memory from something I read in the documentation a while ago.
As for why your toast wasn't showing - did you remember to .show() it? I always used to forget to do that. Toasts can also get missed if they're triggered just as the activity is pausing, since its context goes away. There's a much easier way to test it - just use the Log method. For example, Log.d("My app name", "onPause was just triggered"); The purpose of the "My app name" string is to let you filter by it in LogCat. If you don't know how to display LogCat, and assuming you're using Eclipse, see this answer to another question.

got it to work , was a bit confused of the purpose with onResume(), i was suppose to decleare a onActivityResult() in the first Activity so that the second Activity would return to it right after finish()