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.

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: Swing is not thread safe. For more information see Swing's Threading Policy.

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)

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.BaselineResizeBehavior, 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.
int	getBaseline(int width, int height)           Returns the baseline.
Component.BaselineResizeBehavior	getBaselineResizeBehavior()           Returns an enum indicating how the baseline of the component changes as the size changes.
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.
Point	getLocation(Point rv)           Stores the x,y origin of this component into "return value" rv and returns rv.
Dimension	getMaximumSize()           If the maximum size has been set to a non-null value just returns it.
Dimension	getMinimumSize()           If the minimum size has been set to a non-null value just returns it.
Component	getNextFocusableComponent()           Deprecated. As of 1.4, replaced by FocusTraversalPolicy.
Point	getPopupLocation(MouseEvent event)           Returns the preferred location to display the popup menu in this component's coordinate system.
Dimension	getPreferredSize()           If the preferredSize has been set to a non-null value just returns it.
KeyStroke[]	getRegisteredKeyStrokes()           Returns the KeyStrokes that will initiate registered actions.
JRootPane	getRootPane()           Returns the JRootPane ancestor for this component.
Dimension	getSize(Dimension rv)           Stores the width/height of this component into "return value" rv and returns rv.
Point	getToolTipLocation(MouseEvent event)           Returns the tooltip location in this component's coordinate system.
String	getToolTipText()           Returns the tooltip string that has been set with setToolTipText.
String	getToolTipText(MouseEvent event)           Returns the string to be used as the tooltip for event.
Container	getTopLevelAncestor()           Returns the top-level ancestor of this component (either the containing Window or Applet), or null if this component has not been added to any container.
TransferHandler	getTransferHandler()           Gets the transferHandler property.
String	getUIClassID()           Returns the UIDefaults key used to look up the name of the swing.plaf.ComponentUI class that defines the look and feel for this component.
boolean	getVerifyInputWhenFocusTarget()           Returns the value that indicates whether the input verifier for the current focus owner will be called before this component requests focus.
VetoableChangeListener[]	getVetoableChangeListeners()           Returns an array of all the vetoable change listeners registered on this component.
Rectangle	getVisibleRect()           Returns the Component's "visible rectangle" - the intersection of this component's visible rectangle, new Rectangle(0, 0, getWidth(), getHeight()), and all of its ancestors' visible rectangles.
int	getWidth()           Returns the current width of this component.
int	getX()           Returns the current x coordinate of the component's origin.
int	getY()           Returns the current y coordinate of the component's origin.
void	grabFocus()           Requests that this Component get the input focus, and that this Component's top-level ancestor become the focused Window.
boolean	isDoubleBuffered()           Returns whether this component should use a buffer to paint.
static boolean	isLightweightComponent(Component c)           Returns true if this component is lightweight, that is, if it doesn't have a native window system peer.
boolean	isManagingFocus()           Deprecated. As of 1.4, replaced by Component.setFocusTraversalKeys(int, Set) and Container.setFocusCycleRoot(boolean).
boolean	isOpaque()           Returns true if this component is completely opaque.
boolean	isOptimizedDrawingEnabled()           Returns true if this component tiles its children -- that is, if it can guarantee that the children will not overlap.
boolean	isPaintingForPrint()           Returns true if the current painting operation on this component is part of a print operation.
boolean	isPaintingTile()           Returns true if the component is currently painting a tile.
boolean	isRequestFocusEnabled()           Returns true if this JComponent should get focus; otherwise returns false.
boolean	isValidateRoot()           If this method returns true, revalidate calls by descendants of this component will cause the entire tree beginning with this root to be validated.
void	paint(Graphics g)           Invoked by Swing to draw components.
protected  void	paintBorder(Graphics g)           Paints the component's border.
protected  void	paintChildren(Graphics g)           Paints this component's children.
protected  void	paintComponent(Graphics g)           Calls the UI delegate's paint method, if the UI delegate is non-null.
void	paintImmediately(int x, int y, int w, int h)           Paints the specified region in this component and all of its descendants that overlap the region, immediately.
void	paintImmediately(Rectangle r)           Paints the specified region now.
protected  String	paramString()           Returns a string representation of this JComponent.
void	print(Graphics g)           Invoke this method to print the component to the specified Graphics.
void	printAll(Graphics g)           Invoke this method to print the component.
protected  void	printBorder(Graphics g)           Prints the component's border.
protected  void	printChildren(Graphics g)           Prints this component's children.
protected  void	printComponent(Graphics g)           This is invoked during a printing operation.
protected  void	processComponentKeyEvent(KeyEvent e)           Processes any key events that the component itself recognizes.
protected  boolean	processKeyBinding(KeyStroke ks, KeyEvent e, int condition, boolean pressed)           Invoked to process the key bindings for ks as the result of the KeyEvent e.
protected  void	processKeyEvent(KeyEvent e)           Overrides processKeyEvent to process events.
protected  void	processMouseEvent(MouseEvent e)           Processes mouse events occurring on this component by dispatching them to any registered MouseListener objects, refer to Component.processMouseEvent(MouseEvent) for a complete description of this method.
protected  void	processMouseMotionEvent(MouseEvent e)           Processes mouse motion events, such as MouseEvent.MOUSE_DRAGGED.
void	putClientProperty(Object key, Object value)           Adds an arbitrary key/value "client property" to this component.
void	registerKeyboardAction(ActionListener anAction, KeyStroke aKeyStroke, int aCondition)           This method is now obsolete, please use a combination of getActionMap() and getInputMap() for similiar behavior.
void	registerKeyboardAction(ActionListener anAction, String aCommand, KeyStroke aKeyStroke, int aCondition)           This method is now obsolete, please use a combination of getActionMap() and getInputMap() for similiar behavior.
void	removeAncestorListener(AncestorListener listener)           Unregisters listener so that it will no longer receive AncestorEvents.
void	removeNotify()           Notifies this component that it no longer has a parent component.
void	removeVetoableChangeListener(VetoableChangeListener listener)           Removes a VetoableChangeListener from the listener list.
void	repaint(long tm, int x, int y, int width, int height)           Adds the specified region to the dirty region list if the component is showing.
void	repaint(Rectangle r)           Adds the specified region to the dirty region list if the component is showing.
boolean	requestDefaultFocus()           Deprecated. As of 1.4, replaced by FocusTraversalPolicy.getDefaultComponent(Container).requestFocus()
void	requestFocus()           Requests that this Component gets the input focus.
boolean	requestFocus(boolean temporary)           Requests that this Component gets the input focus.
boolean	requestFocusInWindow()           Requests that this Component gets the input focus.
protected  boolean	requestFocusInWindow(boolean temporary)           Requests that this Component gets the input focus.
void	resetKeyboardActions()           Unregisters all the bindings in the first tier InputMaps and ActionMap.
void	reshape(int x, int y, int w, int h)           Deprecated. As of JDK 5, replaced by Component.setBounds(int, int, int, int). Moves and resizes this component.
void	revalidate()           Supports deferred automatic layout.
void	scrollRectToVisible(Rectangle aRect)           Forwards the scrollRectToVisible() message to the JComponent's parent.
void	setActionMap(ActionMap am)           Sets the ActionMap to am.
void	setAlignmentX(float alignmentX)           Sets the the vertical alignment.
void	setAlignmentY(float alignmentY)           Sets the the horizontal alignment.
void	setAutoscrolls(boolean autoscrolls)           Sets the autoscrolls property.
void	setBackground(Color bg)           Sets the background color of this component.
void	setBorder(Border border)           Sets the border of this component.
void	setComponentPopupMenu(JPopupMenu popup)           Sets the JPopupMenu for this JComponent.
void	setDebugGraphicsOptions(int debugOptions)           Enables or disables diagnostic information about every graphics operation performed within the component or one of its children.
static void	setDefaultLocale(Locale l)           Sets the default locale used to initialize each JComponent's locale property upon creation.
void	setDoubleBuffered(boolean aFlag)           Sets whether this component should use a buffer to paint.
void	setEnabled(boolean enabled)           Sets whether or not this component is enabled.
void	setFocusTraversalKeys(int id, Set<? extends AWTKeyStroke> keystrokes)           Sets the focus traversal keys for a given traversal operation for this Component.
void	setFont(Font font)           Sets the font for this component.
void	setForeground(Color fg)           Sets the foreground color of this component.
void	setInheritsPopupMenu(boolean value)           Sets whether or not getComponentPopupMenu should delegate to the parent if this component does not have a JPopupMenu assigned to it.
void	setInputMap(int condition, InputMap map)           Sets the InputMap to use under the condition condition to map.
void	setInputVerifier(InputVerifier inputVerifier)           Sets the input verifier for this component.
void	setMaximumSize(Dimension maximumSize)           Sets the maximum size of this component to a constant value.
void	setMinimumSize(Dimension minimumSize)           Sets the minimum size of this component to a constant value.
void	setNextFocusableComponent(Component aComponent)           Deprecated. As of 1.4, replaced by FocusTraversalPolicy
void	setOpaque(boolean isOpaque)           If true the component paints every pixel within its bounds.
void	setPreferredSize(Dimension preferredSize)           Sets the preferred size of this component.
void	setRequestFocusEnabled(boolean requestFocusEnabled)           Provides a hint as to whether or not this JComponent should get focus.
void	setToolTipText(String text)           Registers the text to display in a tool tip.
void	setTransferHandler(TransferHandler newHandler)           Sets the transferHandler property, which is null if the component does not support data transfer operations.
protected  void	setUI(ComponentUI newUI)           Sets the look and feel delegate for this component.
void	setVerifyInputWhenFocusTarget(boolean verifyInputWhenFocusTarget)           Sets the value to indicate whether input verifier for the current focus owner will be called before this component requests focus.
void	setVisible(boolean aFlag)           Makes the component visible or invisible.
void	unregisterKeyboardAction(KeyStroke aKeyStroke)           This method is now obsolete.
void	update(Graphics g)           Calls paint.
void	updateUI()           Resets the UI property to a value from the current look and feel.

 

Methods inherited from class java.awt.Container

add, add, add, add, add, addContainerListener, addImpl, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getComponentZOrder, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getLayout, getMousePosition, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicyProvider, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paintComponents, preferredSize, printComponents, processContainerEvent, processEvent, remove, remove, removeAll, removeContainerListener, setComponentZOrder, setFocusCycleRoot, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setLayout, transferFocusBackward, transferFocusDownCycle, validate, validateTree

 

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, createImage, createImage, createVolatileImage, createVolatileImage, disableEvents, dispatchEvent, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getForeground, getGraphicsConfiguration,