Java Reference
In-Depth Information
CHAPTER 6
■ ■ ■
Swing Menus and Toolbars
M
any of the low-level Swing components were covered in the previous two chapters of this
topic. This chapter will delve into Swing's menu-related components. Menus and toolbars help
make your applications more user-friendly by providing visual command options. Users can
avoid the somewhat archaic multiple-key command sequences that are holdovers from programs
such as the early word processor WordStar and the more current emacs programmer's editor.
Although Swing menus do support multiple-key command sequences, the menus (and toolbars)
are designed primarily for on-screen graphical selection with a mouse, rather than the keyboard.
The menu components discussed in this chapter are used as follows:
For each cascading menu, you create a
JMenu
component and add it to the
JMenuBar
.
•
For the selections available from the
JMenu
, you create
JMenuItem
components and add
them to the
JMenu
.
•
To create submenus, you add a new
JMenu
to a
JMenu
and place
JMenuItem
options on the
new menu.
•
•
Then, when a
JMenu
is selected, the system displays its current set of components within
a
JPopupMenu
.
In addition to the basic
JMenuItem
elements, this chapter covers other menu items, such as
JCheckBoxMenuItem
and
JRadioButtonMenuItem
, which you can place within a
JMenu
. You'll also
explore the
JSeparator
class, which serves to divide menu items into logical groups. You'll find
out how to use the
JPopupMenu
class for general support of pop-up menus that appear after a
JMenu
is selected, or in context for any component. As with abstract buttons (the
AbstractButton
class was introduced in Chapter 4), each menu element can have a mnemonic associated with
it for keyboard selection. You'll also learn about the support for keyboard accelerators, which
allow users to avoid going through all the menuing levels for selection.
Besides the individual menu-related components, in this chapter you'll look at the
JMenuBar
selection model and event-related classes specific to menus. The selection model interface
to examine is the
SingleSelectionModel
interface, as well as its default implementation
DefaultSingleSelectionModel
. You'll explore the menu-specific listeners and events
MenuListener
/
MenuEvent
,
MenuKeyListener
/
MenuKeyEvent
, and
MenuDragMouseListener
/
MenuDragMouseEvent
. In addition, you'll examine creating other pop-up components with
Popup
and
PopupFactory
, as well as using toolbars with the
JToolBar
class.
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