From Android 19, you can register an app life cycle callback in your Application class's onCreate() like this:
@Override
public void onCreate() {
super.onCreate();
registerActivityLifecycleCallbacks(new AppLifecycleCallback());
}
The AppLifecycleCallback looks like this:
class AppLifecycleCallback implements Application.ActivityLifecycleCallbacks {
private int numStarted = 0;
@Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
}
@Override
public void onActivityStarted(Activity activity) {
if (numStarted == 0) {
//app went to foreground
}
numStarted++;
}
@Override
public void onActivityResumed(Activity activity) {
}
@Override
public void onActivityPaused(Activity activity) {
}
@Override
public void onActivityStopped(Activity activity) {
numStarted--;
if (numStarted == 0) {
// app went to background
}
}
@Override
public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
}
@Override
public void onActivityDestroyed(Activity activity) {
}
}
