javax.swing
Class JComponent

java.lang.Object   
  java.awt.Component   
      java.awt.Container   
          javax.swing.JComponent

All Implemented Interfaces:

ImageObserver , MenuContainer , Serializable

Direct Known Subclasses:

AbstractButton , BasicInternalFrameTitlePane , Box , Box.Filler , JColorChooser , JComboBox , JFileChooser , JInternalFrame , JInternalFrame.JDesktopIcon , JLabel , JLayeredPane , JList , JMenuBar , JOptionPane , JPanel , JPopupMenu , JProgressBar , JRootPane , JScrollBar , JScrollPane , JSeparator , JSlider , JSpinner , JSplitPane , JTabbedPane , JTable , JTableHeader , JTextComponent , JToolBar , JToolTip , JTree , JViewport

public abstract class JComponent
extends Container   
implements Serializable   

The base class for all Swing components except top-level containers. To use a component that inherits from JComponent, you must place the component in a containment hierarchy whose root is a top-level Swing container. Top-level Swing containers -- such as JFrame, JDialog, and JApplet -- are specialized components that provide a place for other Swing components to paint themselves. For an explanation of containment hierarchies, see Swing Components and the Containment Hierarchy, a section in The Java Tutorial.

The JComponent class provides:

• The base class for both standard and custom components that use the Swing architecture.
• A "pluggable look and feel" (L&F) that can be specified by the programmer or (optionally) selected by the user at runtime. The look and feel for each component is provided by a UI delegate -- an object that descends from ComponentUI . See How to Set the Look and Feel in The Java Tutorial for more information.
• Comprehensive keystroke handling. See the document Keyboard Bindings in Swing, an article in The Swing Connection, for more information.
• Support for tool tips -- short descriptions that pop up when the cursor lingers over a component. See How to Use Tool Tips in The Java Tutorial for more information.
• Support for accessibility. JComponent contains all of the methods in the Accessible interface, but it doesn't actually implement the interface. That is the responsibility of the individual classes that extend JComponent.
• Support for component-specific properties. With the putClientProperty(java.lang.Object, java.lang.Object) and getClientProperty(java.lang.Object) methods, you can associate name-object pairs with any object that descends from JComponent.
• An infrastructure for painting that includes double buffering and support for borders. For more information see Painting and How to Use Borders, both of which are sections in The Java Tutorial.

For more information on these subjects, see the Swing package description and The Java Tutorial section The JComponent Class.

JComponent and its subclasses document default values for certain properties. For example, JTable documents the default row height as 16. Each JComponent subclass that has a ComponentUI will create the ComponentUI as part of its constructor. In order to provide a particular look and feel each ComponentUI may set properties back on the JComponent that created it. For example, a custom look and feel may require JTables to have a row height of 24. The documented defaults are the value of a property BEFORE the ComponentUI has been installed. If you need a specific value for a particular property you should explicitly set it.

In release 1.4, the focus subsystem was rearchitected. For more information, see How to Use the Focus Subsystem, a section in The Java Tutorial.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans^TM has been added to the java.beans package. Please see XMLEncoder .

See Also:

KeyStroke , Action , setBorder(javax.swing.border.Border) , registerKeyboardAction(java.awt.event.ActionListener, java.lang.String, javax.swing.KeyStroke, int) , JOptionPane , setDebugGraphicsOptions(int) , setToolTipText(java.lang.String) , setAutoscrolls(boolean) , Serialized Form

Nested Class Summary

class

JComponent.AccessibleJComponent Inner class of JComponent used to provide default support for accessibility.

Nested classes/interfaces inherited from class java.awt.Container

Container.AccessibleAWTContainer

Nested classes/interfaces inherited from class java.awt.Component

Component.AccessibleAWTComponent , Component.BltBufferStrategy , Component.FlipBufferStrategy

Field Summary

protected AccessibleContext	accessibleContext The AccessibleContext associated with this JComponent.
protected EventListenerList	listenerList A list of event listeners for this component.
static String	TOOL_TIP_TEXT_KEY The comment to display when the cursor is over the component, also known as a "value tip", "flyover help", or "flyover label".
protected ComponentUI	ui The look and feel delegate for this component.
static int	UNDEFINED_CONDITION Constant used by some of the APIs to mean that no condition is defined.
static int	WHEN_ANCESTOR_OF_FOCUSED_COMPONENT Constant used for registerKeyboardAction that means that the command should be invoked when the receiving component is an ancestor of the focused component or is itself the focused component.
static int	WHEN_FOCUSED Constant used for registerKeyboardAction that means that the command should be invoked when the component has the focus.
static int	WHEN_IN_FOCUSED_WINDOW Constant used for registerKeyboardAction that means that the command should be invoked when the receiving component is in the window that has the focus or is itself the focused component.

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT , CENTER_ALIGNMENT , LEFT_ALIGNMENT , RIGHT_ALIGNMENT , TOP_ALIGNMENT

Fields inherited from interface java.awt.image.ImageObserver

ABORT , ALLBITS , ERROR , FRAMEBITS , HEIGHT , PROPERTIES , SOMEBITS , WIDTH

Constructor Summary

JComponent ()
Default JComponent constructor.

Method Summary

void	addAncestorListener (AncestorListener listener) Registers listener so that it will receive AncestorEvents when it or any of its ancestors move or are made visible or invisible.
void	addNotify () Notifies this component that it now has a parent component.
void	addVetoableChangeListener (VetoableChangeListener listener) Adds a VetoableChangeListener to the listener list.
void	computeVisibleRect (Rectangle visibleRect) Returns the Component's "visible rect rectangle" - the intersection of the visible rectangles for this component and all of its ancestors.
boolean	contains (int x, int y) Gives the UI delegate an opportunity to define the precise shape of this component for the sake of mouse processing.
JToolTip	createToolTip () Returns the instance of JToolTip that should be used to display the tooltip.
void	disable () Deprecated. As of JDK version 1.1, replaced by java.awt.Component.setEnabled(boolean).
void	enable () Deprecated. As of JDK version 1.1, replaced by java.awt.Component.setEnabled(boolean).
void	firePropertyChange (String propertyName, boolean oldValue, boolean newValue) Support for reporting bound property changes for boolean properties.
void	firePropertyChange (String propertyName, char oldValue, char newValue) Reports a bound property change.
void	firePropertyChange (String propertyName, int oldValue, int newValue) Support for reporting bound property changes for integer properties.
protected void	fireVetoableChange (String propertyName, Object oldValue, Object newValue) Supports reporting constrained property changes.
AccessibleContext	getAccessibleContext () Returns the AccessibleContext associated with this JComponent.
ActionListener	getActionForKeyStroke (KeyStroke aKeyStroke) Returns the object that will perform the action registered for a given keystroke.
ActionMap	getActionMap () Returns the ActionMap used to determine what Action to fire for particular KeyStroke binding.
float	getAlignmentX () Overrides Container.getAlignmentX to return the vertical alignment.
float	getAlignmentY () Overrides Container.getAlignmentY to return the horizontal alignment.
AncestorListener []	getAncestorListeners () Returns an array of all the ancestor listeners registered on this component.
boolean	getAutoscrolls () Gets the autoscrolls property.
Border	getBorder () Returns the border of this component or null if no border is currently set.
Rectangle	getBounds (Rectangle rv) Stores the bounds of this component into "return value" rv and returns rv.
Object	getClientProperty (Object key) Returns the value of the property with the specified key.
protected Graphics	getComponentGraphics (Graphics g) Returns the graphics object used to paint this component.
JPopupMenu	getComponentPopupMenu () Returns JPopupMenu that assigned for this component.
int	getConditionForKeyStroke (KeyStroke aKeyStroke) Returns the condition that determines whether a registered action occurs in response to the specified keystroke.
int	getDebugGraphicsOptions () Returns the state of graphics debugging.
static Locale	getDefaultLocale () Returns the default locale used to initialize each JComponent's locale property upon creation.
FontMetrics	getFontMetrics (Font font) Gets the FontMetrics for the specified Font.
Graphics	getGraphics () Returns this component's graphics context, which lets you draw on a component.
int	getHeight () Returns the current height of this component.
boolean	getInheritsPopupMenu () Returns true if the JPopupMenu should be inherited from the parent.
InputMap	getInputMap () Returns the InputMap that is used when the component has focus.
InputMap	getInputMap (int condition) Returns the InputMap that is used during condition.
InputVerifier	getInputVerifier () Returns the input verifier for this component.
Insets	getInsets () If a border has been set on this component, returns the border's insets; otherwise calls super.getInsets.
Insets	getInsets (Insets insets) Returns an Insets object containing this component's inset values.
<T extends EventListener > T[]	getListeners (Class <T> listenerType) Returns an array of all the objects currently registered as FooListeners upon this JComponent.
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