Handling Events - Beginning Java 2 SDK - page 759

A long description of the action —a String object that is intended to be used as context
sensitive help.

❑

A mnemonic key for the action - this is a key code of type int .

❑

An action command key - defined by an entry in a KeyMap object associated with a
component.

❑

Just so you are aware of them I have included the complete set here, but we will concentrate on just using the
first three. We haven't met Icon objects before, but we will get to them a little later in this chapter.

You are not obliged to provide for all of these properties in your action classes, but the interface
provides the framework for it. These properties are stored internally in a map collection in your action
class, so the Action interface defines constants that you use as keys for each of the standard properties.
These constants are all of type String , and the ones we are interested in are NAME , SMALL _ ICON , and
SHORT _ DESCRIPTION . The others are ACCELERATOR _ KEY , LONG _ DESCRIPTION , MNEMONIC _ KEY ,
and ACTION _ COMMAND _ KEY . There is another constant of type String defined in the interface with
the name DEFAULT . This is for you to use to store a default property for the action.

The Action interface also declares the following methods:

Method Description

void putValue(String key,
Object value)

Stores the value with the key key in the map
supported by the action class. To store the name of
an action within a class method you might write:

putValue(NAME, theName);

This uses the standard key, NAME to store the
object theName .

Object getValue(String key)

This retrieves the object from the map
corresponding to the key key . To retrieve a small
icon within an action class method you might
write:

Icon lineIcon =
(Icon)getValue(SMALL _ ICON);

boolean isEnabled() Returns true if the action object is enabled and

false otherwise.

void setEnabled(boolean state) Sets the action object as enabled if the argument

state is true and disabled if it is false . This
operates on both the toolbar button and the menu
item if they have been created using the same
object.

Table continued on following page