AppLifeCycleObserver.java

/**
 * Closes the socket connection when app is in background and
 * connects to socket when the app is in foreground.
 */
public class AppLifeCycleObserver implements LifecycleObserver {

    private Context mContext;

    /**
     * Use this constructor to create a new AppLifeCycleObserver
     *
     * @param context
     */
    public AppLifeCycleObserver(Context context) {
        mContext = context;
    }

    /**
     * When app enters foreground
     */
    @OnLifecycleEvent(Lifecycle.Event.ON_START)
    public void onEnterForeground() {
        try {
            EventServiceImpl.getInstance().connect(User.getUsername());
        } catch (URISyntaxException e) {
            Toast.makeText(mContext, "Failed to connect to chat server.", Toast.LENGTH_LONG).show();
            e.printStackTrace();
        }
    }

    /**
     * When app enters background
     */
    @OnLifecycleEvent(Lifecycle.Event.ON_STOP)
    public void onEnterBackground() {
        EventServiceImpl.getInstance().disconnect();
    }
}