detects when cancel is clicked

In RadioListener.java, add:

void onRadioClosed();

in RadioPlayerService.java, add:

private void notifyPlayerClosed() { 
        for (RadioListener mRadioListener : mListenerList) {  
            mRadioListener.onRadioClosed();
        }
    }

in function stopFromNotification() inside the same java file, add:

notifyPlayerClosed();

after:

stop();

That's all 👍