Creating Windows - Beginning Java - page 833

The JMenuBar class defines a menu bar usually found at the top of an application window. A JMenu ob-
ject represents a top-level menu item on a menu bar that drops down a list of menu items when it is clicked.
The items in a menu are defined by the JMenuItem class. The JPopupMenu class defines a context menu that
is typically implemented to appear at the current cursor position when the right mouse button is clicked. A
JCheckBoxMenuItem component is a menu item with a checkbox that is ticked when the item is selected.
The JRadioButtonMenuItem class defines a menu item that is part of a group where only one item can be
selected at any time. The group is created by adding JRadioButtonMenuItem objects to a ButtonGroup ob-
ject. You implement a menu in an application and an applet later in this chapter.
Text Components
The capability of the Swing text components is very wide indeed. The classes in the javax.swing packages
that represent text components are shown in Figure 17-12 . Like all Swing components, they have the JCom-
ponent class as a base.
FIGURE 17-12
The most elementary text component is a JLabel object, which displays as a single line of text. A JLabel
component is passive and does not react to input events so you can't edit it. A JTextField component looks
similar to a label in that it displays a single line of text, but in this case it is editable. A JFormattedTex-
tField component is a JTextField component that can control and format the data that is displayed or
entered. It can supply automatic formatting in many instances so it can automatically display a Date object
as a date for example. A JPasswordField component allows entry of a password as a single line of input
and prevents the characters in the password from being seen.
The JTextArea class defines a component that allows editing of multiline text that is contained within
a given area. A JTextArea component does not support scrolling directly, but it's easy to add scrollbars by
placing the JTextArea component in a JScrollPane container.