Android Service : What happen at the end of Activity life?

Issue

Suppose that Activity A starts Service S and binds to Service S.

1. What will happen to S when A is destroyed?

2. How can I recreate another Activity that binds to S? The sample code in http://developer.android.com/guide/components/bound-services.html unbind the service in onStop(). I think if I open the app again, a new process is created for another instance of A and S. But I want the new activity to get data from the old service.

Solution

What will happen to S when A is destroyed?

If A is the only Activity bound to S and you didn't start the Service via startService(Intent), S will be destroyed. That's because a Service will be alive till the last bound Activity unbounds from the Service. This is documented here.

How can I recreate another Activity that binds to S?

If A is bound and you switch to Activity B via Intent, the Service will be destroyed and recreated when B binds to it.

If you want the Service to be alive even if no Activity is bound to it, you have to call the Servie with startService(Intent). Now it will be around if you explicitly stop it or system means it's time to destroy it. If you don't want this behavior, persist your data and access it at given time.

I think if I open the app again, a new process is created for another instance of A and S

The process remains the same till the process is killed from the system or if you kill the process, which is not recommanded.

Edit:

Only the bound service lifecycle depends on Activities. If you want a stand alone one use startService(). This way it's independent from Activities and runs in background as long as the process of the App is up or you explicitly stop the Service with stopService() / stopSelf(). You could even have a Service in a own App and use IPC to communicate between Apps. It's all a matter of the use case.

As you can see the configuration of a Service is very flexible and you have to decide which fits best for your App.

Answered By - Steve Benett