Listeners

Creating a listener

To create a listener, you create a class and implement the Listener interface.

1. Create a new class.
2. Implement the Listener interface.
3. Create a method that accepts an event as a parameter.
4. Add the @EventListener annotation to the method.
5. Done.

public class MyListener implements Listener {

    @EventListener
    public void onMyEvent(MyEvent event) {
        System.out.println(event.getMessage());
    }
}

Subscribing and unsubscribing a listener

To subscribe or unsubscribe a listener, you use an instance of Sees and use the subscribe or unsubscribe method.

1. Get the default instance of Sees (or create a new instance).
2. Subscribe or unsubscribe a listener.
3. Done.

public class Main {

    public static void main(String[] args) {

        // Get the default instance of `Sees`.
        Sees sees = Sees.getInstance();

        MyListener listener = new MyListener();

        // Subscribe a listener.
        sees.subscribe(listener);

        // Unsubscribe a listener.
        sees.unsubscribe(listener);
    }
}