Hook: Define an Action

Requirement

An action needs to be defined to be associated with a menu element or a button in a FormSheet.

Method of Adaptation

Add Feature

Level of Support

Parameter Pattern

HotSpot

Display

Participants

Action, NewAction

Changes

1. implement NewAction of Action.
2. NewAction.doAction implements Action.doAction .

Constraints

• This Hook can only be invoked from the Define a FormSheet , Create a MenuSheet element or the Define Action For Button In Component hook.

Comments

• Actions are used to associate activities with buttons and menu elements.
• Actions can often be implemented using anonymous inner classes. However, make sure, that there are no (even merely implicit) references to unserializable classes in the Action class.

  All Swing classes should be treated as unserializable, so if your Action has a reference to a Swing class, it becomes unserializable, too. While this was comparatively unproblematic under JDK1.2, it has become a problem with JDK1.3 and further. Here the compiler will create an implicit reference to the enclosing class's instance for each inner class compiled. Therefore, you cannot define Actions as inner classes of Swing components. Defining Actions as inner classes of FormSheets , FormSheetContentCreators , and other Framework classes, however, should be safe.