javax.swing

Class JFrame

  • All Implemented Interfaces:
    ImageObserver, MenuContainer, Serializable, Accessible, RootPaneContainer, WindowConstants 

    public class JFrame
extends Frame
implements WindowConstants, Accessible, RootPaneContainer
    An extended version of java.awt.Frame that adds support for the JFC/Swing component architecture. You can find task-oriented documentation about using JFrame in The Java Tutorial, in the section How to Make Frames.

    The JFrame class is slightly incompatible with Frame. Like all other JFC/Swing top-level containers, a JFrame contains a JRootPane as its only child. The content pane provided by the root pane should, as a rule, contain all the non-menu components displayed by the JFrame. This is different from the AWT Frame case. As a convenience, the add, remove, and setLayout methods of this class are overridden, so that they delegate calls to the corresponding methods of the ContentPane. For example, you can add a child component to a frame as follows: 

           frame.add(child);
    And the child will be added to the contentPane. The content pane will always be non-null. Attempting to set it to null will cause the JFrame to throw an exception. The default content pane will have a BorderLayout manager set on it. Refer to RootPaneContainer for details on adding, removing and setting the LayoutManager of a JFrame.

    Unlike a Frame, a JFrame has some notion of 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(int). To make the JFrame behave the same as a Frame instance, use setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE).

    For more information on content panes and other features that root panes provide, see Using Top-Level Containers in The Java Tutorial.

    In a multi-screen environment, you can create a JFrame on a different screen device. See Frame for more information.

    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.

    See Also:
    JRootPane, setDefaultCloseOperation(int), WindowListener.windowClosing(java.awt.event.WindowEvent), RootPaneContainer

    • Field Detail

      • EXIT_ON_CLOSE

        public static final int EXIT_ON_CLOSE
        The exit application default window close operation. If a window has this set as the close operation and is closed in an applet, a SecurityException may be thrown. It is recommended you only use this in an application.

        Since:
        1.3
        See Also:
        Constant Field Values

      • 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

      • accessibleContext

        protected AccessibleContext accessibleContext
        The accessible context property.

    • 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.

      • setDefaultCloseOperation

        public void setDefaultCloseOperation(int operation)
        Sets the operation that will happen by default when the user initiates a "close" on this frame. You must specify one of the following choices:

        • DO_NOTHING_ON_CLOSE (defined in WindowConstants): Don't do anything; require the program to handle the operation in the windowClosing method of a registered WindowListener object.
        • HIDE_ON_CLOSE (defined in WindowConstants): Automatically hide the frame after invoking any registered WindowListener objects.
        • DISPOSE_ON_CLOSE (defined in WindowConstants): Automatically hide and dispose the frame after invoking any registered WindowListener objects.
        • EXIT_ON_CLOSE (defined in JFrame): Exit the application using the System exit method. Use this only in applications.

        The value is set to HIDE_ON_CLOSE by default. Changes to the value of this property cause the firing of a property change event, with property name "defaultCloseOperation".

        Note: When the last displayable window within the Java virtual machine (VM) is disposed of, the VM may terminate. See AWT Threading Issues for more information.

        Parameters:
        operation - the operation which should be performed when the user closes the frame
        Throws:
        IllegalArgumentException - if defaultCloseOperation value isn't one of the above valid values
        SecurityException - if EXIT_ON_CLOSE has been specified and the SecurityManager will not allow the caller to invoke System.exit
        See Also:
        Window.addWindowListener(java.awt.event.WindowListener), getDefaultCloseOperation(), WindowConstants, Runtime.exit(int)

      • getDefaultCloseOperation

        public int getDefaultCloseOperation()
        Returns the operation that occurs when the user initiates a "close" on this frame.
        Returns:
        an integer indicating the window-close operation
        See Also:
        setDefaultCloseOperation(int)

      • setTransferHandler

        public void setTransferHandler(TransferHandler newHandler)
        Sets the transferHandler property, which is a mechanism to support transfer of data into this component. Use null if the component does not support data transfer operations.

        If the system property suppressSwingDropSupport is false (the default) and the current drop target on this component is either null or not a user-set drop target, this method will change the drop target as follows: If newHandler is null it will clear the drop target. If not null it will install a new DropTarget.

        Note: When used with JFrame, TransferHandler only provides data import capability, as the data export related methods are currently typed to JComponent.

        Please see How to Use Drag and Drop and Data Transfer, a section in The Java Tutorial, for more information.

        Parameters:
        newHandler - the new TransferHandler
        Since:
        1.6
        See Also:
        TransferHandler, getTransferHandler(), Component.setDropTarget(java.awt.dnd.DropTarget)

      • update

        public void update(Graphics g)
        Just calls paint(g). This method was overridden to prevent an unnecessary call to clear the background.
        Overrides:
        update in class  Container
        Parameters:
        g - the Graphics context in which to paint
        See Also:
        Component.update(Graphics)

      • setJMenuBar

        public void setJMenuBar(JMenuBar menubar)
        Sets the menubar for this frame.
        Parameters:
        menubar - the menubar being placed in the frame
        See Also:
        getJMenuBar()

      • 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()

      • setIconImage

        public void setIconImage(Image image)
        Sets the image to be displayed as the icon for this window.

        This method can be used instead of setIconImages() to specify a single image as a window's icon.

        The following statement: 

             setIconImage(image);
        is equivalent to: 
             ArrayList<Image> imageList = new ArrayList<Image>();
     imageList.add(image);
     setIconImages(imageList);

        Note : Native windowing systems may use different images of differing dimensions to represent a window, depending on the context (e.g. window decoration, window list, taskbar, etc.). They could also use just a single image for all contexts or no image at all.

        Overrides:
        setIconImage in class  Frame
        Parameters:
        image - the icon image to be displayed.
        See Also:
        Window.setIconImages(java.util.List<? extends java.awt.Image>), Window.getIconImages()

      • getGraphics

        public Graphics getGraphics()
        Creates a graphics context for this component. This method will return null if this component is currently not displayable.
        Overrides:
        getGraphics in class  Component
        Returns:
        a graphics context for this component, or null if it has none
        Since:
        1.6
        See Also:
        Component.paint(java.awt.Graphics)

      • repaint

        public void repaint(long time,
                    int x,
                    int y,
                    int width,
                    int height)
        Repaints the specified rectangle of this component within time milliseconds. Refer to RepaintManager for details on how the repaint is handled.
        Overrides:
        repaint in class  Component
        Parameters:
        time - maximum time in milliseconds before update
        x - the x coordinate
        y - the y coordinate
        width - the width
        height - the height
        Since:
        1.6
        See Also:
        RepaintManager

      • setDefaultLookAndFeelDecorated

        public static void setDefaultLookAndFeelDecorated(boolean defaultLookAndFeelDecorated)
        Provides a hint as to whether or not newly created JFrames should have their Window decorations (such as borders, widgets to close the window, title...) provided by the current look and feel. If defaultLookAndFeelDecorated is true, the current LookAndFeel supports providing window decorations, and the current window manager supports undecorated windows, then newly created JFrames will have their Window decorations provided by the current LookAndFeel. Otherwise, newly created JFrames will have their Window decorations provided by the current window manager.

        You can get the same effect on a single JFrame by doing the following: 

            JFrame frame = new JFrame();
    frame.setUndecorated(true);
    frame.getRootPane().setWindowDecorationStyle(JRootPane.FRAME);
        Parameters:
        defaultLookAndFeelDecorated - A hint as to whether or not current look and feel should provide window decorations
        Since:
        1.4
        See Also:
        LookAndFeel.getSupportsWindowDecorations()

      • isDefaultLookAndFeelDecorated

        public static boolean isDefaultLookAndFeelDecorated()
        Returns true if newly created JFrames should have their Window decorations provided by the current look and feel. This is only a hint, as certain look and feels may not support this feature.
        Returns:
        true if look and feel should provide Window decorations.
        Since:
        1.4

      • 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.
        Overrides:
        paramString in class  Frame
        Returns:
        a string representation of this JFrame

      • getAccessibleContext

        public AccessibleContext getAccessibleContext()
        Gets the AccessibleContext associated with this JFrame. For JFrames, the AccessibleContext takes the form of an AccessibleJFrame. A new AccessibleJFrame instance is created if necessary.
        Specified by:
        getAccessibleContext in interface  Accessible
        Overrides:
        getAccessibleContext in class  Frame
        Returns:
        an AccessibleJFrame that serves as the AccessibleContext of this JFrame