Java Foundation Classes in a Nutshell

One shortcoming of working with actions is that there is no way to tell a JMenuBar

or JToolBar to display just text or just icons for actions. Although you might like

an action’s name to be displayed in a menu and its icon to be displayed in a tool-

bar, both

JMenuBar and JToolBar display an action’s textual name and its icon.

The

Action inter face helps you implement a clean separation between GUI code

and application logic. Remember, however, that you cannot just instantiate

Action

objects directly. Since Action is a kind of ActionListener, you must define an

individual subclass of

Action that implements the actionPerformed() method for

each of your desired actions. The

AbstractAction class is helpful here; it imple-

ments everything except the

actionPerformed() method.

Tooltips

A Swing component can display context-sensitive help to the user in the form of a

tooltip:asmall window that pops up when the user lets the mouse rest over the

component. You can display text in this window that explains the purpose or

function of the component. Specify this text with the

setToolTipText() method.

This

toolTipText pr operty is inherited from JComponent,soitisshar ed by all

Swing components.

While it is a good idea to provide tooltips for the benefit of your novice users,

your experienced users may find them annoying, so it is nice to provide a way to

tur n them off. You can do this programatically by setting the