I have an Android application that is binding to a persistent service (once started with startService()
).
The service is an integral part of the application and thus is used in almost every Activity. Hence I want to bind to the service just once (instead of binding/unbinding in every Activity) and keep the binding during the lifetime of my application.
I've extended from Application and bind to the service in Application#onCreate(). However I now have the problem that I don't know when my application exists since Application#onTerminate() is never called, see JavaDoc:
This method is for use in emulated process environments. It will never be called on a production Android device, where processes are removed by simply killing them; no user code (including this callback) is executed when doing so.
So how do I cleanly unbind from a service bound in Application?
I solved this problem by counting the references to the service binding in the Application
. Every Activity
has to call acquireBinding()
in their onCreate()
methods and call releaseBinding()
in onDestroy()
. If the reference counter reaches zero the binding is released.
Here's an example:
class MyApp extends Application {
private final AtomicInteger refCount = new AtomicInteger();
private Binding binding;
@Override
public void onCreate() {
// create service binding here
}
public Binding acquireBinding() {
refCount.incrementAndGet();
return binding;
}
public void releaseBinding() {
if (refCount.get() == 0 || refCount.decrementAndGet() == 0) {
// release binding
}
}
}
// Base Activity for all other Activities
abstract class MyBaseActivity extend Activity {
protected MyApp app;
protected Binding binding;
@Override
public void onCreate(Bundle savedBundleState) {
super.onCreate(savedBundleState);
this.app = (MyApp) getApplication();
this.binding = this.app.acquireBinding();
}
@Override
public void onDestroy() {
super.onDestroy();
this.app.releaseBinding();
}
}