Context menus

A context menu appears when the user right-clicks some component. Vaadin supports context menus for Table, Tree, and TreeTable. Menu options are encapsulated using Action instances:

final Action action = new Action("Say hello");

To add actions and respond to them, we must add a Handler. A Handler is an interface with two methods:

public interface Handler extends Serializable {

  public Action[] getActions(Object target, Object sender);

  public void handleAction(Action action, Object sender,
      Object target);

}

getActions must return an array containing all the actions we want to show in our context menu. handleAction will be called when an action is performed (the user clicks a menu item). Here is an example implementation that shows a somewhat uncouth salutation:

table.addActionHandler(new Handler() {
  
  public void handleAction(Action action, Object sender,
      Object target) {
    Notification.show("Ok, here I go... Hello.");
  }
  
  public Action[] getActions(Object...