Interface Component.Listener

All Superinterfaces:

ConnectorEventListener, EventListener, Serializable, SerializableEventListener

Enclosing interface:

Component

public static interface Component.Listener
extends ConnectorEventListener

Listener interface for receiving Component.Events.

Listener interfaces are the basis of all user interaction handling in Vaadin. You have or create a listener object that receives the events. All event types have their corresponding listener types; they are not, however, required to inherit the Component.Listener interface, and they rarely do so.

This generic listener interface is useful typically when you wish to handle events from different component types in a single listener method (componentEvent(). If you handle component events in an anonymous listener class, you normally use the component specific listener class, such as Button.ClickEvent.

 class Listening extends CustomComponent implements Listener {
     Button ok; // Stored for determining the source of an event

     Label status; // For displaying info about the event

     public Listening() {
         VerticalLayout layout = new VerticalLayout();

         // Some miscellaneous component
         TextField name = new TextField("Say it all here");
         name.addListener(this);
         layout.addComponent(name);

         // Handle button clicks as generic events instead
         // of Button.ClickEvent events
         ok = new Button("OK");
         ok.addListener(this);
         layout.addComponent(ok);

         // For displaying information about an event
         status = new Label("");
         layout.addComponent(status);

         setCompositionRoot(layout);
     }

     public void componentEvent(Event event) {
         // Act according to the source of the event
         if (event.getSource() == ok
                 && event.getClass() == Button.ClickEvent.class)
             getWindow().showNotification("Click!");

         // Display source component and event class names
         status.setValue(
                 "Event from " + event.getSource().getClass().getName()
                         + ": " + event.getClass().getName());
     }
 }

 Listening listening = new Listening();
 layout.addComponent(listening);
 

See Also:

Component.addListener(Listener)