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The JComponent Class

Most Swing components are implemented as subclasses of the JComponent(in the API reference documentation) class, which inherits from the Container(in the API reference documentation) class. From JComponent, Swing components inherit the following functionality:
Borders.
Using the setBorder method, you can specify the border that a component displays around its edges. You can specify that a component have extra space around its edges using an EmptyBorder instance. See the BorderFactory(in the API reference documentation) specification and Understanding Borders (an article in The Swing Connection) for more information.

Double buffering.
Double buffering can improve the appearance of a frequently changing component. Now you don't have to write the double buffering code -- Swing provides it for you. By default, Swing components are double buffered. By invoking setDoubleBuffered(false) on a component, you turn off its double buffering.

Tool tips.
By specifying a string with the setToolTipText method, you can provide help to users of a component. When the cursor pauses over the component, the specified string is displayed in a small window that appears near the component. See How to Use Tool Tips for more information.

Keyboard navigation.
Using the registerKeyboardAction method, you can enable the user to use the keyboard, instead of the mouse, to maneuver through the GUI

Note: Some classes provide convenience methods for keyboard actions. For example, AbstractButton provides setMnemonic, which lets you specify the character that, in combination with a look-and-feel-specific modifier key, causes the button's action to be performed. See How to Use Buttons, Check Boxes, and Radio Buttons for an example of using mnemonics in buttons.
The combination of character and modifier keys that the user must press to start an action is represented by a KeyStroke(in the API reference documentation) object. The resulting action event is handled by an ActionListener(in the Creating a User Interface trail) object. Each keyboard action works under exactly one of two conditions: either when the actual component has the focus or when any component in its containing window has the focus.

Properties.
With the putProperty method, you can associate one or more properties (name/object pairs) with any JComponent. For example, a layout manager might use properties to associate a constraints object with each JComponent it manages. You put and get properties using the putClientProperty and getClientProperty methods.

Application-wide pluggable look and feel.
Behind the scenes, each JComponent object has a corresponding ComponentUI object that performs all the drawing, event handling, size determination, and so on for that JComponent. Exactly which ComponentUI object is used depends on the current look and feel, which you can set using the UIManager.setLookAndFeel method.

Support for layout.
With methods such as setPreferredSize, setMinimumSize, setMaximumSize, setAlignmentX, and setAlignmentY, you can specify layout constraints without having to write your own component.

Support for accessibility.
[PENDING: describe]

Support for localization.
[PENDING: describe]


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