Class JPanel

java.lang.Object

java.awt.Component

java.awt.Container

javax.swing.JComponent

javax.swing.JPanel

All Implemented Interfaces:

ImageObserver, MenuContainer, Serializable, Accessible

Direct Known Subclasses:

AbstractColorChooserPanel, JSpinner.DefaultEditor

@JavaBean(defaultProperty="UI",
          description="A generic lightweight container.")
public class JPanel
extends JComponent
implements Accessible

JPanel is a generic lightweight container. For examples and task-oriented documentation for JPanel, see How to Use Panels, 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 has been added to the java.beans package. Please see XMLEncoder.

Since:

1.2

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	JPanel.AccessibleJPanel	This class implements accessibility support for the JPanel class.

Nested classes/interfaces declared in class JComponent

JComponent.AccessibleJComponent

Nested classes/interfaces declared in class Container

Container.AccessibleAWTContainer

Nested classes/interfaces declared in class Component

Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy

Field Summary

Fields declared in class JComponent

listenerList, TOOL_TIP_TEXT_KEY, ui, UNDEFINED_CONDITION, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, WHEN_FOCUSED, WHEN_IN_FOCUSED_WINDOW

Fields declared in class Component

accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields declared in interface ImageObserver

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

Constructor Summary

Constructors

Constructor	Description
JPanel()	Creates a new JPanel with a double buffer and a flow layout.
JPanel(boolean isDoubleBuffered)	Creates a new JPanel with FlowLayout and the specified buffering strategy.
JPanel(LayoutManager layout)	Create a new buffered JPanel with the specified layout manager
JPanel(LayoutManager layout, boolean isDoubleBuffered)	Creates a new JPanel with the specified layout manager and buffering strategy.

Method Summary

Modifier and Type	Method	Description
AccessibleContext	getAccessibleContext()	Gets the AccessibleContext associated with this JPanel.
PanelUI	getUI()	Returns the look and feel (L&F) object that renders this component.
String	getUIClassID()	Returns a string that specifies the name of the L&F class that renders this component.
protected String	paramString()	Returns a string representation of this JPanel.
void	setUI(PanelUI ui)	Sets the look and feel (L&F) object that renders this component.
void	updateUI()	Resets the UI property with a value from the current look and feel.

Methods declared in class JComponent

addAncestorListener, addNotify, addVetoableChangeListener, computeVisibleRect, contains, createToolTip, disable, enable, firePropertyChange, firePropertyChange, fireVetoableChange, getActionForKeyStroke, getActionMap, getAlignmentX, getAlignmentY, getAncestorListeners, getAutoscrolls, getBaseline, getBaselineResizeBehavior, getBorder, getBounds, getClientProperty, getComponentGraphics, getComponentPopupMenu, getConditionForKeyStroke, getDebugGraphicsOptions, getDefaultLocale, getFontMetrics, getGraphics, getHeight, getInheritsPopupMenu, getInputMap, getInputMap, getInputVerifier, getInsets, getInsets, getListeners, getLocation, getMaximumSize, getMinimumSize, getNextFocusableComponent, getPopupLocation, getPreferredSize, getRegisteredKeyStrokes, getRootPane, getSize, getToolTipLocation, getToolTipText, getToolTipText, getTopLevelAncestor, getTransferHandler, getVerifyInputWhenFocusTarget, getVetoableChangeListeners, getVisibleRect, getWidth, getX, getY, grabFocus, hide, isDoubleBuffered, isLightweightComponent, isManagingFocus, isOpaque, isOptimizedDrawingEnabled, isPaintingForPrint, isPaintingOrigin, isPaintingTile, isRequestFocusEnabled, isValidateRoot, paint, paintBorder, paintChildren, paintComponent, paintImmediately, paintImmediately, print, printAll, printBorder, printChildren, printComponent, processComponentKeyEvent, processKeyBinding, processKeyEvent, processMouseEvent, processMouseMotionEvent, putClientProperty, registerKeyboardAction, registerKeyboardAction, removeAncestorListener, removeNotify, removeVetoableChangeListener, repaint, repaint, requestDefaultFocus, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, resetKeyboardActions, reshape, revalidate, scrollRectToVisible, setActionMap, setAlignmentX, setAlignmentY, setAutoscrolls, setBackground, setBorder, setComponentPopupMenu, setDebugGraphicsOptions, setDefaultLocale, setDoubleBuffered, setEnabled, setFocusTraversalKeys, setFont, setForeground, setInheritsPopupMenu, setInputMap, setInputVerifier, setMaximumSize, setMinimumSize, setNextFocusableComponent, setOpaque, setPreferredSize, setRequestFocusEnabled, setToolTipText, setTransferHandler, setUI, setVerifyInputWhenFocusTarget, setVisible, unregisterKeyboardAction, update

Methods declared in class 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, transferFocusDownCycle, validate, validateTree

Methods declared in class 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, firePropertyChange, getBackground, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getForeground, getGraphicsConfiguration, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getToolkit, getTreeLock, gotFocus, handleEvent, hasFocus, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, postEvent, prepareImage, prepareImage, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, resize, resize, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setFocusable, setFocusTraversalKeysEnabled, setIgnoreRepaint, setLocale, setLocation, setLocation, setMixingCutoutShape, setName, setSize, setSize, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

JPanel

public JPanel(LayoutManager layout,
 boolean isDoubleBuffered)

Creates a new JPanel with the specified layout manager and buffering strategy.

Parameters:

layout - the LayoutManager to use

isDoubleBuffered - a boolean, true for double-buffering, which uses additional memory space to achieve fast, flicker-free updates

JPanel

public JPanel(LayoutManager layout)

Create a new buffered JPanel with the specified layout manager

Parameters:

layout - the LayoutManager to use

JPanel

public JPanel(boolean isDoubleBuffered)

Creates a new JPanel with FlowLayout and the specified buffering strategy. If isDoubleBuffered is true, the JPanel will use a double buffer.

Parameters:

isDoubleBuffered - a boolean, true for double-buffering, which uses additional memory space to achieve fast, flicker-free updates

JPanel

public JPanel()

Creates a new JPanel with a double buffer and a flow layout.

Method Details

updateUI

public void updateUI()

Resets the UI property with a value from the current look and feel.

Overrides:

updateUI in class JComponent

See Also:

• JComponent.updateUI()

getUI

public PanelUI getUI()

Returns the look and feel (L&F) object that renders this component.

Overrides:

getUI in class JComponent

Returns:

the PanelUI object that renders this component

Since:

1.4

setUI

@BeanProperty(hidden=true,
              visualUpdate=true,
              description="The UI object that implements the Component's LookAndFeel.")
public void setUI(PanelUI ui)

Sets the look and feel (L&F) object that renders this component.

Parameters:

ui - the PanelUI L&F object

Since:

1.4

See Also:

• UIDefaults.getUI(JComponent)

getUIClassID

@BeanProperty(bound=false,
              expert=true,
              description="A string that specifies the name of the L&F class.")
public String getUIClassID()

Returns a string that specifies the name of the L&F class that renders this component.

Overrides:

getUIClassID in class JComponent

Returns:

the string "PanelUI"

See Also:

• JComponent.getUIClassID()
• UIDefaults.getUI(JComponent)

paramString

protected String paramString()

Returns a string representation of this JPanel. This method is intended to be used only for debugging purposes, and the content and format of the returned string may vary between implementations. The returned string may be empty but may not be null.

Overrides:

paramString in class JComponent

Returns:

a string representation of this JPanel.

getAccessibleContext

@BeanProperty(bound=false)
public AccessibleContext getAccessibleContext()

Gets the AccessibleContext associated with this JPanel. For JPanels, the AccessibleContext takes the form of an AccessibleJPanel. A new AccessibleJPanel instance is created if necessary.

Specified by:

getAccessibleContext in interface Accessible

Overrides:

getAccessibleContext in class Component

Returns:

an AccessibleJPanel that serves as the AccessibleContext of this JPanel