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onPause onResume alternative?

I've got a bit of a dilemma and not quite sure how to solve it. Here's the scenario...
I have a multi activity application which plays music from the time it starts to the time the application exits.
However, if I use onPause / onResume to detect when the activity is sent to the background and pause the music in onPause and resume play in onResume, the music "skips" briefly when I start the next activity as the calling activity is finished once the startActivity() is called.
If I don't pause / resume the music in onPause / onResume the music plays smoothly but does NOT stop if the home key is pressed and the activity is sent to the back.
Is there a way to detect an activity is sent to the background (using, say a timer and application flag) without having to use onPause / onResume?
If this is not possible or too hard to implement (I'm still learning as we all are), is there a way to create an "invisible" launcher activity which runs in the background to handle such things but never seen?
As always, thanks in advance.

Turns out there's no simple way around this.
First thing you should do, is move your music streaming to a service, this way it doesn't depend on any activity.
Then you need to tell the service to stop when the entire application is in the background, not when one activity is paused. this fine answer suggests adding a timer to your application, and wait for a couple of seconds after an activity is paused. Of no other activity in the app is resumed - the app is assumed to be in the background.
I wouldn't add a timer to your application, but rather let your music playing service do this (notify the service in each onPause and onResume). Also, two seconds is too long for playing music, I'd start with 500ms and see if it's acceptable.

It's pretty simple IMHO
What you are trying to figure is if the new activity is from your application, continue playing the music, else stop.
You can do this with a boolean flag.
Here's the algorithm:
-boolean flag is set to true in onResume in all activities
-Keep the statements which pause the music in onPause
-Put the above statements (in onPause) in an if(boolean flag)
-whenever an event happens to start a new activity i.e. a button is clicked in your activities, etc, clear the flag (set it to false) in the event listener - eg: the button's onClickListener
This should work

The changeover between activities looks like this:
Activity A onPause
Activity B onCreate (or onRestart if it's already created)
Activity B onStart
Activity B onResume
Activity A onStop
You have a few options how to take advantage of this. You can subclass Application, and keep a boolean in the application class. Make a base Activity that does the following:
In onPause(), call the application to change the boolean to false.
In onResume(), call the application to change the boolean to true.
In onStop(), call the application to stop the music unless the boolean is set to true.
If all of your Activities extend this base Activity, then this will work. When A stops, as long as B was another one of your Activities, it will have resumed and set the boolean to true, so your music will keep playing.
There's a second approach that uses a Bound Service, where you bind in onStart() and unbind in onStop(). You can explore that on your own if you so desire.

You can (and in the fact should) use service to handle the music player. This is the component you are calling as "invisible activity".
If you start it by bindService() method in onResume and unbind in onPause() of each activity in your application it should run all the time. When no activity is bound to the running service the service is stopped by system, so all you need is just stop the music in the onDestroy() or in the onUnbind() method of the service.
Here you have a nice diagram of the Service lifecycle: http://www.tutorialspoint.com/android/android_services.htm
I'm not 100% if automatic management of servers lifecycle will be enough - in such case you can use startService() method to keep the service working all the time, when onUnbind of service is called put some delayed (i.e. using Handler.postDelayed(Runnable r) ) check if after i.e. after 1s service is still unbound and stopSelf() in such case.

OK, here's the solution and it's fairly straightforward once I thought about it in a more logical way.
What I have done is:-
Create a public static int called activityCount.
In the onCreate function of each activity I increment activityCount by 1.
I #Override public void finish() and decrement activityCount by one
and call super.finish().
In onPause if activityCount == 1, pause the music.
In onResume if activityCount == 1, play the music.
This is giving me the desired effect by continuously playing the music but when the home button is clicked the music stops and resumes when the activity is resumed.
Thanks for all the suggestions as it helped me think more logically.

How to handle service stopped in background

My ex colleague developed a service which plays music in background. However if user wants to exit from program then application calls below code to stop service. Service stops but i cannot handle it while overriding onDestroy method
Activity realAct = context.getParent();
if (realAct == null) {
realAct = context;
}
ContextWrapper cw = new ContextWrapper(realAct);
cw.stopService(new Intent(cw, MyPlayerService.class));
edit:
Briefly, Activity Main starts Activity Sub then Activity Sub starts Service. Then i press back button so Activity Sub finishes. When i am in Activity Main I call above stopservice code. So onDestroy method of Service is not called

Try again to use method like that in code of your service :
#Override
public void onDestroy()
{
super.onDestroy();
//your code
}
It has to work !

Are you trying to stop the service when the user exits from application?
onDestroy is called when system needs to kill activities due to insufficient resources. Just because you pressed back on your app doesn't mean onDestroy gets called immediately.
But if you want to force close your app to have it automatically invoke onDestroy, call
finish()
on wherever you are exiting your application from.
If you want to invoke onDestroy upon user pressing back button to exit, Override onBackPressed() and invoke finish() from there.
But really, this is an antipattern so I'd recommend using onPause() instead.
Edit Upon OP Edit:
I think we need to have more details on how you are instantiating the service but here are some additional thoughts:
Have you overridden onDestroy properly and calling the super method?
If this is the case, the only other possibility I can think of is that you still have ServiceConnection objects bound to the service with BIND_AUTO_CREATE set. Until all of these bindings are removed, service will not get destroyed.
So make sure to do both:
unbindService(conn);
stopService(intent);

How to start/stop a service from an activity?

I have a toggle button in my main activity. I want a service to start when the toggle button is on and stop when it is off. The activity may be closed at any time. I want the activity to 'remember' the service it had started before the activity was closed and the activity should be able to close this service it had started on its previous run.
What should I do?

Read this Service first, then use these guys to control it: startService() and stopService(). About remember, you can use static variable to check the status of service, and change it on onCreate and onDestroy of your service, it's like one of the solutions.

When should I start and stop my notification service?

I don't want the notification service to be working while the user is in the application. As of right now I have it starting in the onCreate and onResume methods and stopping in the onPause method. Is that correct?
Also, is it sufficient to specify the intent and execute stopService(intent) to stop it? There isn't a direct relationship between the start and stop methods except they reference the same class.
Thank you for any help.

Here is the activity lifecycle.
As you will see, onCreate() and onResume() are called before the activity is created so you do not want to start your notification service there. You should stop it instead. It is a good idea to do it once in onResume() because it is the entry point of your activity.
onPause() is where user navigates away from the activity so it is where you will want to start the service again.

Stopping and starting a Service based on application state

I have a Service which tracks the location of the user. Currently, the Service boots when the application starts and stops when the application terminates. Unfortunately, if users keep the application in the background, the Service never stops and drains battery.
I would like the Service to stop when my application is not in the foreground. I was hoping the Application class would let me Override onPause and onResume handlers, but it does not have them. Is there another way I can accomplish this?

I haven't tested this yet, but it looks like if you use Context#bindService() (instead of Context#startService()), the service should stop when no more activities are bound to it. (see Service lifecycle).
Then use onPause()/onResume() in each activity to bind/unbind from the service.
Alternatively, you could add a pair of methods on your service which tell it to start/stop listening for location updates and call it from each activity's onResume()/onPause(). The service would still be running, but the location updates wouldn't be draining the battery.

Reading all the above answers I would suggest Simply add a boolean global flag for each activity & put it in your onResume & onPause & also while launching an Activity Something like this
public void onPause()
{
super.onPause();
activity1IsResumed = true;
}
&same for onResume
& similarly when launching a new Activity
startActivityForResult(myintent ,0);
activity2IsResumed = true;
activity1IsResumed = false;
then in your Service simply check
if(activity1IsResumed || activity2IsResumed || activity3IsResumed)
{
//your logic
}
else
{
//another logic
//or dont run location tracker
}
& you are done!

You should override the onPause and onResume methods on your Activity. If you have multiple activities you may want to have a common base class for them and put the start/stop logic into the base class.

I have not tried this approach but I think you can override the home key of android device by using KeyEvent.KEYCODE_HOME and you can use stopService(Intent) to stop your service and when again application resumes, you can write startService(Intent) in the onResume() method of your Activity.
This way I think your service will only stop when user explicitly presses home button to take application in the background and not when he switches from one activity to another.

What I would suggest is overriding the onPause/onReume methods as others have said. Without knowing more about the flow of your application and interactions between Activities, I can't give much more information beyond guesswork.
If your Activities are persistent, however, my recommendation would be to utilize the Intents better when switching between Activities.
For instance, each Activity should have a boolean "transition" flag. So, when you move from one Activity to the next, you set up an Intent extra:
intent.putExtra("transition",true);
Followed in the receiving Activity by: (in onCreate)
intent.getBooleanExtra("transition",false);
This way, for each Activity that launches, you can know whether it has come from another Activity, or if it has been launched from a home screen launcher. Thus, if it gets a true transition, then onPause should NOT stop the service--that means you will be returning to the previous Activity after it returns. If it receives no "transition" extra, or a false transition, then you can safely assume there is no Activity underneath it waiting to take over for the current one.
On the first Activity, you will simply need to stop the service if you are switching to another Activity, which you should be able to figure out programmatically if one Activity is started from another.

It sounds like the real problem is how to only stop the service when you go to an activity that isn't one of your own? One way would be to in your onPause method to stop the activity. Do this for all your activities. Then override your startActivity method. And in here do a conditional test to confirm that you are purposefully navigating to one of your own. If your are set a flag to true.
Now go back to your on pause overridden method. And only stop your service if the flag is not equal to true. Set the flag to false.
All events that navigate away will close your service. Navigating to your own will leave it intact.
Do the overriding in a base class that all your activities extend.
Writeen in my andolroid. Will post ezaple later.

Try using the Bound Services technique to accomplish this.
Bound Services | Android Developers
You can use bound services in a way such that the service will stop when no activities are bound to it. This way, when the app is not in the foreground, the service will not be running. When the user brings the app back to the foreground, the Activity will bind to the service and the service will resume.

Create methods registerActivity() and unRegisterActivity() in your Application object and implement first method in all you acts onResume() and second in acts onPause().
First method add activity to List<Activity> instance in your app object, unRegisterActivity() checks size of list in every call if==0 stopService();.