Application Backgrounding And Foregrounding Tracking

Lifecycle.java

// Usually these are added as private fields somewhere in Application class

    /**
     * Handle application foregrounding.
     */
    private final class LifecycleListener implements Application.ActivityLifecycleCallbacks {
        private Application application;

        LifecycleListener(Application app) {
            application = app;
            application.registerActivityLifecycleCallbacks(this);
            logger.d("Subscribed to ActivityLifecycleCallbacks");
        }

        void unregister() {
            application.unregisterActivityLifecycleCallbacks(this);
            application = null;
            logger.d("Unsubscribed from ActivityLifecycleCallbacks");
        }

        private void checkForegrounded() {
            if (wasBackgrounded && !isDisposed) {
                logger.d("Application foregrounded");
                wasBackgrounded = false;
                reconnect(nativeHandle);
            }            
        }

        @Override
        public void onActivityCreated(Activity a, Bundle b) {
            checkForegrounded();
        }

        @Override
        public void onActivityStarted(Activity a) {
            checkForegrounded();
        }

        @Override
        public void onActivityResumed(Activity a) {
            checkForegrounded();
        }

        @Override
        public void onActivityPaused(Activity a) {
            // ignored
        }

        @Override
        public void onActivityStopped(Activity a) {
            // ignored
        }

        @Override
        public void onActivityDestroyed(Activity a) {
            // ignored
        }

        @Override
        public void onActivitySaveInstanceState(Activity a, Bundle b) {
            // ignored
        }
    }

    /**
     * Handle application backgrounding.
     */
    private final class LifecycleListener2 implements ComponentCallbacks2 {
        private Application application;

        LifecycleListener2(Application app) {
            application = app;
            application.registerComponentCallbacks(this);
            logger.d("Subscribed to ComponentCallbacks2");
        }

        void unregister() {
            application.unregisterComponentCallbacks(this);
            application = null;
            logger.d("Unsubscribed from ComponentCallbacks2");
        }

        @Override
        public void onConfigurationChanged(final Configuration newConfig) {
            // ignored
        }

        @Override
        public void onLowMemory() {
            // ignored
        }

        @Override
        public void onTrimMemory(final int level) {
            if (level == ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN) {
                wasBackgrounded = true;
                logger.d("Application backgrounded");
            }
        }
    }