javax.swing
Class JFrame

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.Container
              |
              +--java.awt.Window
                    |
                    +--java.awt.Frame
                          |
                          +--javax.swing.JFrame

public class JFrame

extends Frame

implements WindowConstants, Accessible, RootPaneContainer

An extended version of java.awt.Frame that adds support for interposing input and painting behavior in front of the frame's children (see glassPane), support for special children that are managed by a LayeredPane (see rootPane) and for Swing MenuBars.

The JFrame class is slightly incompatible with java.awt.Frame. JFrame contains a JRootPane as it's only child. The contentPane should be the parent of any children of the JFrame. This is different than java.awt.Frame, e.g. to add a child to an AWT Frame you'd write:

       frame.add(child);
 

However using JFrame you need to add the child to the JFrames contentPane instead:

       frame.getContentPane().add(child);
 

The same is true for setting LayoutManagers, removing components, listing children, etc. All these methods should normally be sent to the contentPane() instead of the JFrame itself. The contentPane() will always be non-null. Attempting to set it to null will cause the JFrame to throw an exception. The default contentPane() will have a BorderLayout manager set on it.

Please see the JRootPane documentation for a complete description of the contentPane, glassPane, and layeredPane properties.

Unlike its parent class, java.awt.Frame, you can tell a JFrame how to respond when the user attempts to close the window. The default behavior is to simply hide the JFrame when the user closes the window. To change the default behavior, you invoke the method setDefaultCloseOperation. To make the JFrame remain open unless you handle the window-closing event and explicitly invoke dispose() (or exit the app, which is also pretty effective), use setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE). That makes the JFrame behave the same as java.awt.Frame. A third option lets you completely dispose of the window when it closes, instead of merely hiding it.

For the keyboard keys used by this component in the standard Look and Feel (L&F) renditions, see the JFrame key assignments.

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. A future release of Swing will provide support for long term persistence.

See Also:

JRootPane, setDefaultCloseOperation(int), WindowListener.windowClosing(java.awt.event.WindowEvent), Serialized Form

Inner Class Summary

protected class

JFrame.AccessibleJFrame The class used to obtain the AccessibleRole for this object.

Field Summary

protected AccessibleContext	accessibleContext The accessible context property
protected JRootPane	rootPane The JRootPane instance that manages the contentPane and optional menuBar for this frame, as well as the glassPane.
protected boolean	rootPaneCheckingEnabled If true then calls to add and setLayout cause an exception to be thrown.

Fields inherited from class java.awt.Frame

CROSSHAIR_CURSOR, DEFAULT_CURSOR, E_RESIZE_CURSOR, HAND_CURSOR, ICONIFIED, MOVE_CURSOR, N_RESIZE_CURSOR, NE_RESIZE_CURSOR, NORMAL, NW_RESIZE_CURSOR, S_RESIZE_CURSOR, SE_RESIZE_CURSOR, SW_RESIZE_CURSOR, TEXT_CURSOR, W_RESIZE_CURSOR, WAIT_CURSOR

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Constructor Summary

JFrame()
Constructs a new Frame that is initially invisible.

JFrame(String title)
Constructs a new, initially invisible Frame with the specified title.

Method Summary

protected void	addImpl(Component comp, Object constraints, int index) By default, children may not be added directly to a this component, they must be added to its contentPane instead.
protected JRootPane	createRootPane() Called by the constructor methods to create the default rootPane.
protected void	frameInit() Called by the constructors to init the JFrame properly.
AccessibleContext	getAccessibleContext() Get the AccessibleContext associated with this JFrame
Container	getContentPane() Returns the contentPane object for this frame.
int	getDefaultCloseOperation() Returns the operation which occurs when the user initiates a "close" on this frame.
Component	getGlassPane() Returns the glassPane object for this frame.
JMenuBar	getJMenuBar() Returns the menubar set on this frame.
JLayeredPane	getLayeredPane() Returns the layeredPane object for this frame.
JRootPane	getRootPane() Returns the rootPane object for this frame.
protected boolean	isRootPaneCheckingEnabled() Returns whether calls to add and setLayout cause an exception to be thrown.
protected String	paramString() Returns a string representation of this JFrame.
protected void	processKeyEvent(KeyEvent e) Processes key events occurring on this component and, if appropriate, passes them on to components in the frame which have registered interest in them.
protected void	processWindowEvent(WindowEvent e) Processes window events occurring on this component.
void	setContentPane(Container contentPane) Sets the contentPane property.
void	setDefaultCloseOperation(int operation) Sets the operation which will happen by default when the user initiates a "close" on this frame.
void	setGlassPane(Component glassPane) Sets the glassPane property.
void	setJMenuBar(JMenuBar menubar) Sets the menubar for this frame.
void	setLayeredPane(JLayeredPane layeredPane) Sets the layeredPane property.
void	setLayout(LayoutManager manager) By default the layout of this component may not be set, the layout of its contentPane should be set instead.
protected void	setRootPane(JRootPane root) Sets the rootPane property.
protected void	setRootPaneCheckingEnabled(boolean enabled) Determines whether calls to add and setLayout cause an exception to be thrown.
void	update(Graphics g) Just calls paint(g).

Methods inherited from class java.awt.Frame

addNotify, finalize, getCursorType, getFrames, getIconImage, getMenuBar, getState, getTitle, isResizable, remove, removeNotify, setCursor, setIconImage, setMenuBar, setResizable, setState, setTitle

Methods inherited from class java.awt.Window

addWindowListener, applyResourceBundle, applyResourceBundle, dispose, getFocusOwner, getInputContext, getLocale, getOwnedWindows, getOwner, getToolkit, getWarningString, isShowing, pack, postEvent, processEvent, removeWindowListener, show, toBack, toFront

Methods inherited from class java.awt.Container

add, add, add, add, add, addContainerListener, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getAlignmentX, getAlignmentY, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getInsets, getLayout, getMaximumSize, getMinimumSize, getPreferredSize, insets, invalidate, isAncestorOf, layout, list, list, locate, minimumSize, paint, paintComponents, preferredSize, print, printComponents, processContainerEvent, remove, remove, removeAll, removeContainerListener, setFont, validate, validateTree

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, disable, disableEvents, dispatchEvent, enable, enable, enableEvents, enableInputMethods, firePropertyChange, getBackground, getBounds, getBounds, getColorModel, getComponentOrientation, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getHeight, getInputMethodRequests, getLocation, getLocation, getLocationOnScreen, getName, getParent, getPeer, getSize, getSize, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, isDisplayable, isDoubleBuffered, isEnabled, isFocusTraversable, isLightweight, isOpaque, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, prepareImage, prepareImage, printAll, processComponentEvent, processFocusEvent, processInputMethodEvent, processMouseEvent, processMouseMotionEvent, removeComponentListener, removeFocusListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setForeground, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, size, toString, transferFocus

Methods inherited from class java.lang.Object

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

Field Detail

rootPane

protected JRootPane rootPane

The JRootPane instance that manages the contentPane and optional menuBar for this frame, as well as the glassPane.

See Also:

JRootPane, RootPaneContainer

rootPaneCheckingEnabled

protected boolean rootPaneCheckingEnabled

If true then calls to add and setLayout cause an exception to be thrown.

See Also:

isRootPaneCheckingEnabled(), setRootPaneCheckingEnabled(boolean)

accessibleContext

protected AccessibleContext accessibleContext

The accessible context property

Constructor Detail

JFrame

public JFrame()

Constructs a new Frame that is initially invisible.

See Also:

Component.setSize(int, int), Component.setVisible(boolean)

JFrame

public JFrame(String title)

Constructs a new, initially invisible Frame with the specified title.

Parameters:

title - the title for the frame

See Also:

Component.setSize(int, int), Component.setVisible(boolean)

Method Detail

frameInit

protected void frameInit()

Called by the constructors to init the JFrame properly.

createRootPane

protected JRootPane createRootPane()

Called by the constructor methods to create the default rootPane.

processKeyEvent

protected void processKeyEvent(KeyEvent e)

Processes key events occurring on this component and, if appropriate, passes them on to components in the frame which have registered interest in them.

Parameters:

e - the key event

Overrides:

processKeyEvent in class Component

See Also:

Component.processKeyEvent(java.awt.event.KeyEvent)

processWindowEvent

protected void processWindowEvent(WindowEvent e)

Processes window events occurring on this component. Hides the window or disposes of it, as specified by the setting of the defaultCloseOperation property.

Parameters:

e - the window event

Overrides:

processWindowEvent in class Window

See Also:

setDefaultCloseOperation(int), Window.processWindowEvent(java.awt.event.WindowEvent)

setDefaultCloseOperation

public void setDefaultCloseOperation(int operation)

Sets the operation which will happen by default when the user initiates a "close" on this frame. The possible choices are defined in the WindowConstants interface:

• DO_NOTHING_ON_CLOSE - do not do anything - require the program to handle the operation in the windowClosing method of a registered WindowListener object.
• HIDE_ON_CLOSE - automatically hide the frame after invoking any registered WindowListener objects
• DISPOSE_ON_CLOSE - automatically hide and dispose the frame after invoking any registered WindowListener objects

The value is set to HIDE_ON_CLOSE by default.

See Also:

Window.addWindowListener(java.awt.event.WindowListener), getDefaultCloseOperation()

getDefaultCloseOperation

public int getDefaultCloseOperation()

Returns the operation which occurs when the user initiates a "close" on this frame.

Returns:

an int indicating the window-close operation

See Also:

setDefaultCloseOperation(int)

update

public void update(Graphics g)

Just calls paint(g). This method was overridden to prevent an unneccessary call to clear the background.

Parameters:

g - the Graphics context in which to paint

Overrides:

update in class Container

setJMenuBar

public void setJMenuBar(JMenuBar menubar)

Sets the menubar for this frame.

Parameters:

menubar - the menubar being placed in the frame

See Also:

getJMenuBar()

getJMenuBar

public JMenuBar getJMenuBar()

Returns the menubar set on this frame.

See Also:

setJMenuBar(javax.swing.JMenuBar)

isRootPaneCheckingEnabled

protected boolean isRootPaneCheckingEnabled()

Returns whether calls to add and setLayout cause an exception to be thrown.

Returns:

true if add and setLayout are checked

See Also:

addImpl(java.awt.Component, java.lang.Object, int), setLayout(java.awt.LayoutManager), setRootPaneCheckingEnabled(boolean)

setRootPaneCheckingEnabled

protected void setRootPaneCheckingEnabled(boolean enabled)

Determines whether calls to add and setLayout cause an exception to be thrown.

Parameters:

enabled - a boolean value, true if checking is to be enabled, which cause the exceptions to be thrown

See Also:

addImpl(java.awt.Component, java.lang.Object, int), setLayout(java.awt.LayoutManager), isRootPaneCheckingEnabled()

addImpl

protected void addImpl(Component comp,
                       Object constraints,
                       int index)

By default, children may not be added directly to a this component, they must be added to its contentPane instead. For example:

 thisComponent.getContentPane().add(child)
 

An attempt to add to directly to this component will cause an runtime exception to be thrown. Subclasses can disable this behavior.

Throws:

Error - if called with rootPaneChecking true

Overrides:

addImpl in class Container

See Also:

setRootPaneCheckingEnabled(boolean)

setLayout

public void setLayout(LayoutManager manager)

By default the layout of this component may not be set, the layout of its contentPane should be set instead. For example:

 thiComponent.getContentPane().setLayout(new BorderLayout())
 

An attempt to set the layout of this component will cause an runtime exception to be thrown. Subclasses can disable this behavior.

Throws:

Error - if called with rootPaneChecking true

Overrides:

setLayout in class Container

See Also:

setRootPaneCheckingEnabled(boolean)

getRootPane

public JRootPane getRootPane()

Returns the rootPane object for this frame.

Specified by:

getRootPane in interface RootPaneContainer

See Also:

setRootPane(javax.swing.JRootPane), RootPaneContainer.getRootPane()

setRootPane

protected void setRootPane(JRootPane root)

Sets the rootPane property. This method is called by the constructor.

Parameters:

root - the rootPane object for this frame

See Also:

getRootPane()

getContentPane

public Container getContentPane()

Returns the contentPane object for this frame.

Specified by:

getContentPane in interface RootPaneContainer

See Also:

setContentPane(java.awt.Container), RootPaneContainer.getContentPane()

setContentPane

public void setContentPane(Container contentPane)

Sets the contentPane property. This method is called by the constructor.

Specified by:

setContentPane in interface RootPaneContainer

Parameters:

contentPane - the contentPane object for this frame

Throws:

IllegalComponentStateException - (a runtime exception) if the content pane parameter is null

See Also:

getContentPane(), RootPaneContainer.setContentPane(java.awt.Container)

getLayeredPane

public JLayeredPane getLayeredPane()

Returns the layeredPane object for this frame.

Specified by:

getLayeredPane in interface RootPaneContainer

See Also:

setLayeredPane(javax.swing.JLayeredPane), RootPaneContainer.getLayeredPane()

setLayeredPane

public void setLayeredPane(JLayeredPane layeredPane)

Sets the layeredPane property. This method is called by the constructor.

Specified by:

setLayeredPane in interface RootPaneContainer

Parameters:

layeredPane - the layeredPane object for this frame

Throws:

IllegalComponentStateException - (a runtime exception) if the layered pane parameter is null

See Also:

getLayeredPane(), RootPaneContainer.setLayeredPane(javax.swing.JLayeredPane)

getGlassPane

public Component getGlassPane()

Returns the glassPane object for this frame.

Specified by:

getGlassPane in interface RootPaneContainer

See Also:

setGlassPane(java.awt.Component), RootPaneContainer.getGlassPane()

setGlassPane

public void setGlassPane(Component glassPane)

Sets the glassPane property. This method is called by the constructor.

Specified by:

setGlassPane in interface RootPaneContainer

Parameters:

glassPane - the glassPane object for this frame

See Also:

getGlassPane(), RootPaneContainer.setGlassPane(java.awt.Component)

paramString

protected String paramString()

Returns a string representation of this JFrame. 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.

Overriding paramString() to provide information about the specific new aspects of the JFC components.

Returns:

a string representation of this JFrame.

Overrides:

paramString in class Frame

getAccessibleContext

public AccessibleContext getAccessibleContext()

Get the AccessibleContext associated with this JFrame

Specified by:

getAccessibleContext in interface Accessible

Returns:

the AccessibleContext of this JFrame