javax.swing

Class JComponent

Contents

    • Field Detail

      • ui

        protected transient ComponentUI ui
        The look and feel delegate for this component.

      • listenerList

        protected EventListenerList listenerList
        A list of event listeners for this component.

      • WHEN_FOCUSED

        public static final int WHEN_FOCUSED
        Constant used for registerKeyboardAction that means that the command should be invoked when the component has the focus.
        See Also:
        Constant Field Values

      • WHEN_ANCESTOR_OF_FOCUSED_COMPONENT

        public static final 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.
        See Also:
        Constant Field Values

      • WHEN_IN_FOCUSED_WINDOW

        public static final 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.
        See Also:
        Constant Field Values

      • UNDEFINED_CONDITION

        public static final int UNDEFINED_CONDITION
        Constant used by some of the APIs to mean that no condition is defined.
        See Also:
        Constant Field Values

      • TOOL_TIP_TEXT_KEY

        public static final 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".
        See Also:
        Constant Field Values

      • accessibleContext

        protected AccessibleContext accessibleContext
        The AccessibleContext associated with this JComponent.

    • Constructor Detail

      • JComponent

        public JComponent()
        Default JComponent constructor. This constructor does very little initialization beyond calling the Container constructor. For example, the initial layout manager is null. It does, however, set the component's locale property to the value returned by JComponent.getDefaultLocale.
        See Also:
        getDefaultLocale()

    • Method Detail

      • setInheritsPopupMenu

        public 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.

        The default value for this is false, but some JComponent subclasses that are implemented as a number of JComponents may set this to true.

        This is a bound property.

        Parameters:
        value - whether or not the JPopupMenu is inherited
        Since:
        1.5
        See Also:
        setComponentPopupMenu(javax.swing.JPopupMenu)

      • setComponentPopupMenu

        public void setComponentPopupMenu(JPopupMenu popup)
        Sets the JPopupMenu for this JComponent. The UI is responsible for registering bindings and adding the necessary listeners such that the JPopupMenu will be shown at the appropriate time. When the JPopupMenu is shown depends upon the look and feel: some may show it on a mouse event, some may enable a key binding.

        If popup is null, and getInheritsPopupMenu returns true, then getComponentPopupMenu will be delegated to the parent. This provides for a way to make all child components inherit the popupmenu of the parent.

        This is a bound property.

        Parameters:
        popup - - the popup that will be assigned to this component may be null
        Since:
        1.5
        See Also:
        getComponentPopupMenu()

      • getComponentPopupMenu

        public JPopupMenu getComponentPopupMenu()
        Returns JPopupMenu that assigned for this component. If this component does not have a JPopupMenu assigned to it and getInheritsPopupMenu is true, this will return getParent().getComponentPopupMenu() (assuming the parent is valid.)
        Returns:
        JPopupMenu assigned for this component or null if no popup assigned
        Since:
        1.5
        See Also:
        setComponentPopupMenu(javax.swing.JPopupMenu)

      • setUI

        protected void setUI(ComponentUI newUI)
        Sets the look and feel delegate for this component. JComponent subclasses generally override this method to narrow the argument type. For example, in JSlider: 
         public void setUI(SliderUI newUI) {
     super.setUI(newUI);
 }

        Additionally JComponent subclasses must provide a getUI method that returns the correct type. For example: 

         public SliderUI getUI() {
     return (SliderUI)ui;
 }
        Parameters:
        newUI - the new UI delegate
        See Also:
        updateUI(), UIManager.getLookAndFeel(), UIManager.getUI(javax.swing.JComponent)

      • getUIClassID

        public 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. Most applications will never need to call this method. Subclasses of JComponent that support pluggable look and feel should override this method to return a UIDefaults key that maps to the ComponentUI subclass that defines their look and feel.
        Returns:
        the UIDefaults key for a ComponentUI subclass
        See Also:
        UIDefaults.getUI(javax.swing.JComponent)

      • getComponentGraphics

        protected Graphics getComponentGraphics(Graphics g)
        Returns the graphics object used to paint this component. If DebugGraphics is turned on we create a new DebugGraphics object if necessary. Otherwise we just configure the specified graphics object's foreground and font.
        Parameters:
        g - the original Graphics object
        Returns:
        a Graphics object configured for this component

      • paintComponent

        protected void paintComponent(Graphics g)
        Calls the UI delegate's paint method, if the UI delegate is non-null. We pass the delegate a copy of the Graphics object to protect the rest of the paint code from irrevocable changes (for example, Graphics.translate).

        If you override this in a subclass you should not make permanent changes to the passed in Graphics. For example, you should not alter the clip Rectangle or modify the transform. If you need to do these operations you may find it easier to create a new Graphics from the passed in Graphics and manipulate it. Further, if you do not invoker super's implementation you must honor the opaque property, that is if this component is opaque, you must completely fill in the background in a non-opaque color. If you do not honor the opaque property you will likely see visual artifacts.

        The passed in Graphics object might have a transform other than the identify transform installed on it. In this case, you might get unexpected results if you cumulatively apply another transform.

        Parameters:
        g - the Graphics object to protect
        See Also:
        paint(java.awt.Graphics), ComponentUI

      • paintChildren

        protected void paintChildren(Graphics g)
        Paints this component's children. If shouldUseBuffer is true, no component ancestor has a buffer and the component children can use a buffer if they have one. Otherwise, one ancestor has a buffer currently in use and children should not use a buffer to paint.
        Parameters:
        g - the Graphics context in which to paint
        See Also:
        paint(java.awt.Graphics), Container.paint(java.awt.Graphics)

      • paintBorder

        protected void paintBorder(Graphics g)
        Paints the component's border.

        If you override this in a subclass you should not make permanent changes to the passed in Graphics. For example, you should not alter the clip Rectangle or modify the transform. If you need to do these operations you may find it easier to create a new Graphics from the passed in Graphics and manipulate it.

        Parameters:
        g - the Graphics context in which to paint
        See Also:
        paint(java.awt.Graphics), setBorder(javax.swing.border.Border)

      • paint

        public void paint(Graphics g)
        Invoked by Swing to draw components. Applications should not invoke paint directly, but should instead use the repaint method to schedule the component for redrawing.

        This method actually delegates the work of painting to three protected methods: paintComponent, paintBorder, and paintChildren. They're called in the order listed to ensure that children appear on top of component itself. Generally speaking, the component and its children should not paint in the insets area allocated to the border. Subclasses can just override this method, as always. A subclass that just wants to specialize the UI (look and feel) delegate's paint method should just override paintComponent.

        Overrides:
        paint in class Container
        Parameters:
        g - the Graphics context in which to paint
        See Also:
        paintComponent(java.awt.Graphics), paintBorder(java.awt.Graphics), paintChildren(java.awt.Graphics), getComponentGraphics(java.awt.Graphics), repaint(long, int, int, int, int)

      • print

        public void print(Graphics g)
        Invoke this method to print the component to the specified Graphics. This method will result in invocations of printComponent, printBorder and printChildren. It is recommended that you override one of the previously mentioned methods rather than this one if your intention is to customize the way printing looks. However, it can be useful to override this method should you want to prepare state before invoking the superclass behavior. As an example, if you wanted to change the component's background color before printing, you could do the following: 
             public void print(Graphics g) {
         Color orig = getBackground();
         setBackground(Color.WHITE);

         // wrap in try/finally so that we always restore the state
         try {
             super.print(g);
         } finally {
             setBackground(orig);
         }
     }

        Alternatively, or for components that delegate painting to other objects, you can query during painting whether or not the component is in the midst of a print operation. The isPaintingForPrint method provides this ability and its return value will be changed by this method: to true immediately before rendering and to false immediately after. With each change a property change event is fired on this component with the name "paintingForPrint".

        This method sets the component's state such that the double buffer will not be used: painting will be done directly on the passed in Graphics.

        Overrides:
        print in class Container
        Parameters:
        g - the Graphics context in which to paint
        See Also:
        printComponent(java.awt.Graphics), printBorder(java.awt.Graphics), printChildren(java.awt.Graphics), isPaintingForPrint()

      • printComponent

        protected void printComponent(Graphics g)
        This is invoked during a printing operation. This is implemented to invoke paintComponent on the component. Override this if you wish to add special painting behavior when printing.
        Parameters:
        g - the Graphics context in which to paint
        Since:
        1.3
        See Also:
        print(java.awt.Graphics)

      • printChildren

        protected void printChildren(Graphics g)
        Prints this component's children. This is implemented to invoke paintChildren on the component. Override this if you wish to print the children differently than painting.
        Parameters:
        g - the Graphics context in which to paint
        Since:
        1.3
        See Also:
        print(java.awt.Graphics)

      • printBorder

        protected void printBorder(Graphics g)
        Prints the component's border. This is implemented to invoke paintBorder on the component. Override this if you wish to print the border differently that it is painted.
        Parameters:
        g - the Graphics context in which to paint
        Since:
        1.3
        See Also:
        print(java.awt.Graphics)

      • isPaintingTile

        public boolean isPaintingTile()
        Returns true if the component is currently painting a tile. If this method returns true, paint will be called again for another tile. This method returns false if you are not painting a tile or if the last tile is painted. Use this method to keep some state you might need between tiles.
        Returns:
        true if the component is currently painting a tile, false otherwise

      • isPaintingForPrint

        public final boolean isPaintingForPrint()
        Returns true if the current painting operation on this component is part of a print operation. This method is useful when you want to customize what you print versus what you show on the screen.

        You can detect changes in the value of this property by listening for property change events on this component with name "paintingForPrint".

        Note: This method provides complimentary functionality to that provided by other high level Swing printing APIs. However, it deals strictly with painting and should not be confused as providing information on higher level print processes. For example, a JTable.print() operation doesn't necessarily result in a continuous rendering of the full component, and the return value of this method can change multiple times during that operation. It is even possible for the component to be painted to the screen while the printing process is ongoing. In such a case, the return value of this method is true when, and only when, the table is being painted as part of the printing process.

        Returns:
        true if the current painting operation on this component is part of a print operation
        Since:
        1.6
        See Also:
        print(java.awt.Graphics)

      • setNextFocusableComponent

        @Deprecated
public void setNextFocusableComponent(Component aComponent)
        Deprecated. As of 1.4, replaced by FocusTraversalPolicy
        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.

        Overrides the default FocusTraversalPolicy for this JComponent's focus traversal cycle by unconditionally setting the specified Component as the next Component in the cycle, and this JComponent as the specified Component's previous Component in the cycle.

        Parameters:
        aComponent - the Component that should follow this JComponent in the focus traversal cycle
        See Also:
        getNextFocusableComponent(), FocusTraversalPolicy

      • getNextFocusableComponent

        @Deprecated
public Component getNextFocusableComponent()
        Deprecated. As of 1.4, replaced by FocusTraversalPolicy.
        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.

        Returns the Component set by a prior call to setNextFocusableComponent(Component) on this JComponent.

        Returns:
        the Component that will follow this JComponent in the focus traversal cycle, or null if none has been explicitly specified
        See Also:
        setNextFocusableComponent(java.awt.Component)

      • setRequestFocusEnabled

        public void setRequestFocusEnabled(boolean requestFocusEnabled)
        Provides a hint as to whether or not this JComponent should get focus. This is only a hint, and it is up to consumers that are requesting focus to honor this property. This is typically honored for mouse operations, but not keyboard operations. For example, look and feels could verify this property is true before requesting focus during a mouse operation. This would often times be used if you did not want a mouse press on a JComponent to steal focus, but did want the JComponent to be traversable via the keyboard. If you do not want this JComponent focusable at all, use the setFocusable method instead.

        Please see How to Use the Focus Subsystem, a section in The Java Tutorial, for more information.

        Parameters:
        requestFocusEnabled - indicates whether you want this JComponent to be focusable or not
        See Also:
        Focus Specification, Component.setFocusable(boolean)

      • grabFocus

        public void grabFocus()
        Requests that this Component get the input focus, and that this Component's top-level ancestor become the focused Window. This component must be displayable, visible, and focusable for the request to be granted.

        This method is intended for use by focus implementations. Client code should not use this method; instead, it should use requestFocusInWindow().

        See Also:
        requestFocusInWindow()

      • setVerifyInputWhenFocusTarget

        public 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. The default is true. Set to false on components such as a Cancel button or a scrollbar, which should activate even if the input in the current focus owner is not "passed" by the input verifier for that component.
        Parameters:
        verifyInputWhenFocusTarget - value for the verifyInputWhenFocusTarget property
        Since:
        1.3
        See Also:
        InputVerifier, setInputVerifier(javax.swing.InputVerifier), getInputVerifier(), getVerifyInputWhenFocusTarget()

      • getPreferredSize

        public Dimension getPreferredSize()
        If the preferredSize has been set to a non-null value just returns it. If the UI delegate's getPreferredSize method returns a non null value then return that; otherwise defer to the component's layout manager.
        Overrides:
        getPreferredSize in class Container
        Returns:
        the value of the preferredSize property
        See Also:
        setPreferredSize(java.awt.Dimension), ComponentUI

      • setMaximumSize

        public void setMaximumSize(Dimension maximumSize)
        Sets the maximum size of this component to a constant value. Subsequent calls to getMaximumSize will always return this value; the component's UI will not be asked to compute it. Setting the maximum size to null restores the default behavior.
        Overrides:
        setMaximumSize in class Component
        Parameters:
        maximumSize - a Dimension containing the desired maximum allowable size
        See Also:
        getMaximumSize()

      • getMaximumSize

        public Dimension getMaximumSize()
        If the maximum size has been set to a non-null value just returns it. If the UI delegate's getMaximumSize method returns a non-null value then return that; otherwise defer to the component's layout manager.
        Overrides:
        getMaximumSize in class Container
        Returns:
        the value of the maximumSize property
        See Also:
        setMaximumSize(java.awt.Dimension), ComponentUI

      • setMinimumSize

        public void setMinimumSize(Dimension minimumSize)
        Sets the minimum size of this component to a constant value. Subsequent calls to getMinimumSize will always return this value; the component's UI will not be asked to compute it. Setting the minimum size to null restores the default behavior.
        Overrides:
        setMinimumSize in class Component
        Parameters:
        minimumSize - the new minimum size of this component
        See Also:
        getMinimumSize()

      • getMinimumSize

        public Dimension getMinimumSize()
        If the minimum size has been set to a non-null value just returns it. If the UI delegate's getMinimumSize method returns a non-null value then return that; otherwise defer to the component's layout manager.
        Overrides:
        getMinimumSize in class Container
        Returns:
        the value of the minimumSize property
        See Also:
        setMinimumSize(java.awt.Dimension), ComponentUI

      • contains

        public 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.
        Overrides:
        contains in class Component
        Parameters:
        x - the x coordinate of the point
        y - the y coordinate of the point
        Returns:
        true if this component logically contains x,y
        See Also:
        Component.contains(int, int), ComponentUI

      • setBorder

        public void setBorder(Border border)
        Sets the border of this component. The Border object is responsible for defining the insets for the component (overriding any insets set directly on the component) and for optionally rendering any border decorations within the bounds of those insets. Borders should be used (rather than insets) for creating both decorative and non-decorative (such as margins and padding) regions for a swing component. Compound borders can be used to nest multiple borders within a single component.

        Although technically you can set the border on any object that inherits from JComponent, the look and feel implementation of many standard Swing components doesn't work well with user-set borders. In general, when you want to set a border on a standard Swing component other than JPanel or JLabel, we recommend that you put the component in a JPanel and set the border on the JPanel.

        This is a bound property.

        Parameters:
        border - the border to be rendered for this component
        See Also:
        Border, CompoundBorder

      • getInsets

        public Insets getInsets(Insets insets)
        Returns an Insets object containing this component's inset values. The passed-in Insets object will be reused if possible. Calling methods cannot assume that the same object will be returned, however. All existing values within this object are overwritten. If insets is null, this will allocate a new one.
        Parameters:
        insets - the Insets object, which can be reused
        Returns:
        the Insets object
        See Also:
        getInsets()

      • setAlignmentY

        public void setAlignmentY(float alignmentY)
        Sets the the horizontal alignment.
        Parameters:
        alignmentY - the new horizontal alignment
        See Also:
        getAlignmentY()

      • setAlignmentX

        public void setAlignmentX(float alignmentX)
        Sets the the vertical alignment.
        Parameters:
        alignmentX - the new vertical alignment
        See Also:
        getAlignmentX()

      • setInputVerifier

        public void setInputVerifier(InputVerifier inputVerifier)
        Sets the input verifier for this component.
        Parameters:
        inputVerifier - the new input verifier
        Since:
        1.3
        See Also:
        InputVerifier

      • getInputVerifier

        public InputVerifier getInputVerifier()
        Returns the input verifier for this component.
        Returns:
        the inputVerifier property
        Since:
        1.3
        See Also:
        InputVerifier

      • getGraphics

        public Graphics getGraphics()
        Returns this component's graphics context, which lets you draw on a component. Use this method to get a Graphics object and then invoke operations on that object to draw on the component.
        Overrides:
        getGraphics in class Component
        Returns:
        this components graphics context
        See Also:
        Component.paint(java.awt.Graphics)

      • setDebugGraphicsOptions

        public void setDebugGraphicsOptions(int debugOptions)
        Enables or disables diagnostic information about every graphics operation performed within the component or one of its children.
        Parameters:
        debugOptions - determines how the component should display the information; one of the following options:
        • DebugGraphics.LOG_OPTION - causes a text message to be printed.
        • DebugGraphics.FLASH_OPTION - causes the drawing to flash several times.
        • DebugGraphics.BUFFERED_OPTION - creates an ExternalWindow that displays the operations performed on the View's offscreen buffer.
        • DebugGraphics.NONE_OPTION disables debugging.
        • A value of 0 causes no changes to the debugging options.
        debugOptions is bitwise OR'd into the current value

      • getDebugGraphicsOptions

        public int getDebugGraphicsOptions()
        Returns the state of graphics debugging.
        Returns:
        a bitwise OR'd flag of zero or more of the following options:
        • DebugGraphics.LOG_OPTION - causes a text message to be printed.
        • DebugGraphics.FLASH_OPTION - causes the drawing to flash several times.
        • DebugGraphics.BUFFERED_OPTION - creates an ExternalWindow that displays the operations performed on the View's offscreen buffer.
        • DebugGraphics.NONE_OPTION disables debugging.
        • A value of 0 causes no changes to the debugging options.
        See Also:
        setDebugGraphicsOptions(int)

      • registerKeyboardAction

        public 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. For example, to bind the KeyStroke aKeyStroke to the Action anAction now use: 
           component.getInputMap().put(aKeyStroke, aCommand);
   component.getActionMap().put(aCommmand, anAction);
        The above assumes you want the binding to be applicable for WHEN_FOCUSED. To register bindings for other focus states use the getInputMap method that takes an integer.

        Register a new keyboard action. anAction will be invoked if a key event matching aKeyStroke occurs and aCondition is verified. The KeyStroke object defines a particular combination of a keyboard key and one or more modifiers (alt, shift, ctrl, meta).

        The aCommand will be set in the delivered event if specified.

        The aCondition can be one of:

        WHEN_FOCUSED
        The action will be invoked only when the keystroke occurs while the component has the focus.
        WHEN_IN_FOCUSED_WINDOW
        The action will be invoked when the keystroke occurs while the component has the focus or if the component is in the window that has the focus. Note that the component need not be an immediate descendent of the window -- it can be anywhere in the window's containment hierarchy. In other words, whenever any component in the window has the focus, the action registered with this component is invoked.
        WHEN_ANCESTOR_OF_FOCUSED_COMPONENT
        The action will be invoked when the keystroke occurs while the component has the focus or if the component is an ancestor of the component that has the focus.

        The combination of keystrokes and conditions lets you define high level (semantic) action events for a specified keystroke+modifier combination (using the KeyStroke class) and direct to a parent or child of a component that has the focus, or to the component itself. In other words, in any hierarchical structure of components, an arbitrary key-combination can be immediately directed to the appropriate component in the hierarchy, and cause a specific method to be invoked (usually by way of adapter objects).

        If an action has already been registered for the receiving container, with the same charCode and the same modifiers, anAction will replace the action.

        Parameters:
        anAction - the Action to be registered
        aCommand - the command to be set in the delivered event
        aKeyStroke - the KeyStroke to bind to the action
        aCondition - the condition that needs to be met, see above
        See Also:
        KeyStroke

      • registerKeyboardAction

        public void registerKeyboardAction(ActionListener anAction,
                          KeyStroke aKeyStroke,
                          int aCondition)
        This method is now obsolete, please use a combination of getActionMap() and getInputMap() for similiar behavior.

      • unregisterKeyboardAction

        public void unregisterKeyboardAction(KeyStroke aKeyStroke)
        This method is now obsolete. To unregister an existing binding you can either remove the binding from the ActionMap/InputMap, or place a dummy binding the InputMap. Removing the binding from the InputMap allows bindings in parent InputMaps to be active, whereas putting a dummy binding in the InputMap effectively disables the binding from ever happening.

        Unregisters a keyboard action. This will remove the binding from the ActionMap (if it exists) as well as the InputMaps.

      • getConditionForKeyStroke

        public int getConditionForKeyStroke(KeyStroke aKeyStroke)
        Returns the condition that determines whether a registered action occurs in response to the specified keystroke.

        For Java 2 platform v1.3, a KeyStroke can be associated with more than one condition. For example, 'a' could be bound for the two conditions WHEN_FOCUSED and WHEN_IN_FOCUSED_WINDOW condition.

        Returns:
        the action-keystroke condition

      • getActionForKeyStroke

        public ActionListener getActionForKeyStroke(KeyStroke aKeyStroke)
        Returns the object that will perform the action registered for a given keystroke.
        Returns:
        the ActionListener object invoked when the keystroke occurs

      • resetKeyboardActions

        public void resetKeyboardActions()
        Unregisters all the bindings in the first tier InputMaps and ActionMap. This has the effect of removing any local bindings, and allowing the bindings defined in parent InputMap/ActionMaps (the UI is usually defined in the second tier) to persist.

      • setInputMap

        public final void setInputMap(int condition,
               InputMap map)
        Sets the InputMap to use under the condition condition to map. A null value implies you do not want any bindings to be used, even from the UI. This will not reinstall the UI InputMap (if there was one). condition has one of the following values:
        • WHEN_IN_FOCUSED_WINDOW
        • WHEN_FOCUSED
        • WHEN_ANCESTOR_OF_FOCUSED_COMPONENT
        If condition is WHEN_IN_FOCUSED_WINDOW and map is not a ComponentInputMap, an IllegalArgumentException will be thrown. Similarly, if condition is not one of the values listed, an IllegalArgumentException will be thrown.
        Parameters:
        condition - one of the values listed above
        map - the InputMap to use for the given condition
        Throws:
        IllegalArgumentException - if condition is WHEN_IN_FOCUSED_WINDOW and map is not an instance of ComponentInputMap; or if condition is not one of the legal values specified above
        Since:
        1.3

      • getInputMap

        public final InputMap getInputMap(int condition)
        Returns the InputMap that is used during condition.
        Parameters:
        condition - one of WHEN_IN_FOCUSED_WINDOW, WHEN_FOCUSED, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT
        Returns:
        the InputMap for the specified condition
        Since:
        1.3

      • getInputMap

        public final InputMap getInputMap()
        Returns the InputMap that is used when the component has focus. This is convenience method for getInputMap(WHEN_FOCUSED).
        Returns:
        the InputMap used when the component has focus
        Since:
        1.3

      • setActionMap

        public final void setActionMap(ActionMap am)
        Sets the ActionMap to am. This does not set the parent of the am to be the ActionMap from the UI (if there was one), it is up to the caller to have done this.
        Parameters:
        am - the new ActionMap
        Since:
        1.3

      • getActionMap

        public final ActionMap getActionMap()
        Returns the ActionMap used to determine what Action to fire for particular KeyStroke binding. The returned ActionMap, unless otherwise set, will have the ActionMap from the UI set as the parent.
        Returns:
        the ActionMap containing the key/action bindings
        Since:
        1.3

      • getBaseline

        public int getBaseline(int width,
              int height)
        Returns the baseline. The baseline is measured from the top of the component. This method is primarily meant for LayoutManagers to align components along their baseline. A return value less than 0 indicates this component does not have a reasonable baseline and that LayoutManagers should not align this component on its baseline.

        This method calls into the ComponentUI method of the same name. If this component does not have a ComponentUI -1 will be returned. If a value >= 0 is returned, then the component has a valid baseline for any size >= the minimum size and getBaselineResizeBehavior can be used to determine how the baseline changes with size.

        Overrides:
        getBaseline in class Component
        Parameters:
        width - the width to get the baseline for
        height - the height to get the baseline for
        Returns:
        the baseline or < 0 indicating there is no reasonable baseline
        Throws:
        IllegalArgumentException - if width or height is < 0
        Since:
        1.6
        See Also:
        getBaselineResizeBehavior(), FontMetrics

      • getBaselineResizeBehavior

        public Component.BaselineResizeBehavior getBaselineResizeBehavior()
        Returns an enum indicating how the baseline of the component changes as the size changes. This method is primarily meant for layout managers and GUI builders.

        This method calls into the ComponentUI method of the same name. If this component does not have a ComponentUI BaselineResizeBehavior.OTHER will be returned. Subclasses should never return null; if the baseline can not be calculated return BaselineResizeBehavior.OTHER. Callers should first ask for the baseline using getBaseline and if a value >= 0 is returned use this method. It is acceptable for this method to return a value other than BaselineResizeBehavior.OTHER even if getBaseline returns a value less than 0.

        Overrides:
        getBaselineResizeBehavior in class Component
        Returns:
        an enum indicating how the baseline changes as the component size changes
        Since:
        1.6
        See Also:
        getBaseline(int, int)

      • requestDefaultFocus

        @Deprecated
public boolean requestDefaultFocus()
        Deprecated. As of 1.4, replaced by FocusTraversalPolicy.getDefaultComponent(Container).requestFocus()
        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.

        Requests focus on this JComponent's FocusTraversalPolicy's default Component. If this JComponent is a focus cycle root, then its FocusTraversalPolicy is used. Otherwise, the FocusTraversalPolicy of this JComponent's focus-cycle-root ancestor is used.

        See Also:
        FocusTraversalPolicy.getDefaultComponent(java.awt.Container)

      • setEnabled

        public void setEnabled(boolean enabled)
        Sets whether or not this component is enabled. A component that is enabled may respond to user input, while a component that is not enabled cannot respond to user input. Some components may alter their visual representation when they are disabled in order to provide feedback to the user that they cannot take input.

        Note: Disabling a component does not disable its children.

        Note: Disabling a lightweight component does not prevent it from receiving MouseEvents.

        Overrides:
        setEnabled in class Component
        Parameters:
        enabled - true if this component should be enabled, false otherwise
        See Also:
        Component.isEnabled(), Component.isLightweight()

      • setForeground

        public void setForeground(Color fg)
        Sets the foreground color of this component. It is up to the look and feel to honor this property, some may choose to ignore it.
        Overrides:
        setForeground in class Component
        Parameters:
        fg - the desired foreground Color
        See Also:
        Component.getForeground()

      • setBackground

        public void setBackground(Color bg)
        Sets the background color of this component. The background color is used only if the component is opaque, and only by subclasses of JComponent or ComponentUI implementations. Direct subclasses of JComponent must override paintComponent to honor this property.

        It is up to the look and feel to honor this property, some may choose to ignore it.

        Overrides:
        setBackground in class Component
        Parameters:
        bg - the desired background Color
        See Also:
        Component.getBackground(), setOpaque(boolean)

      • setFont

        public void setFont(Font font)
        Sets the font for this component.
        Overrides:
        setFont in class Container
        Parameters:
        font - the desired Font for this component
        See Also:
        Component.getFont()

      • getDefaultLocale

        public static Locale getDefaultLocale()
        Returns the default locale used to initialize each JComponent's locale property upon creation. The default locale has "AppContext" scope so that applets (and potentially multiple lightweight applications running in a single VM) can have their own setting. An applet can safely alter its default locale because it will have no affect on other applets (or the browser).
        Returns:
        the default Locale.
        Since:
        1.4
        See Also:
        setDefaultLocale(java.util.Locale), Component.getLocale(), Component.setLocale(java.util.Locale)

      • setDefaultLocale

        public static void setDefaultLocale(Locale l)
        Sets the default locale used to initialize each JComponent's locale property upon creation. The initial value is the VM's default locale. The default locale has "AppContext" scope so that applets (and potentially multiple lightweight applications running in a single VM) can have their own setting. An applet can safely alter its default locale because it will have no affect on other applets (or the browser).
        Parameters:
        l - the desired default Locale for new components.
        Since:
        1.4
        See Also:
        getDefaultLocale(), Component.getLocale(), Component.setLocale(java.util.Locale)

      • processComponentKeyEvent

        protected void processComponentKeyEvent(KeyEvent e)
        Processes any key events that the component itself recognizes. This is called after the focus manager and any interested listeners have been given a chance to steal away the event. This method is called only if the event has not yet been consumed. This method is called prior to the keyboard UI logic.

        This method is implemented to do nothing. Subclasses would normally override this method if they process some key events themselves. If the event is processed, it should be consumed.

      • processKeyBinding

        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. This obtains the appropriate InputMap, gets the binding, gets the action from the ActionMap, and then (if the action is found and the component is enabled) invokes notifyAction to notify the action.
        Parameters:
        ks - the KeyStroke queried
        e - the KeyEvent
        condition - one of the following values:
        • JComponent.WHEN_FOCUSED
        • JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT
        • JComponent.WHEN_IN_FOCUSED_WINDOW
        pressed - true if the key is pressed
        Returns:
        true if there was a binding to an action, and the action was enabled
        Since:
        1.3

      • setToolTipText

        public void setToolTipText(String text)
        Registers the text to display in a tool tip. The text displays when the cursor lingers over the component.

        See How to Use Tool Tips in The Java Tutorial for further documentation.

        Parameters:
        text - the string to display; if the text is null, the tool tip is turned off for this component
        See Also:
        TOOL_TIP_TEXT_KEY

      • getToolTipText

        public String getToolTipText()
        Returns the tooltip string that has been set with setToolTipText.
        Returns:
        the text of the tool tip
        See Also:
        TOOL_TIP_TEXT_KEY

      • getToolTipText

        public String getToolTipText(MouseEvent event)
        Returns the string to be used as the tooltip for event. By default this returns any string set using setToolTipText. If a component provides more extensive API to support differing tooltips at different locations, this method should be overridden.

      • getToolTipLocation

        public Point getToolTipLocation(MouseEvent event)
        Returns the tooltip location in this component's coordinate system. If null is returned, Swing will choose a location. The default implementation returns null.
        Parameters:
        event - the MouseEvent that caused the ToolTipManager to show the tooltip
        Returns:
        always returns null

      • getPopupLocation

        public Point getPopupLocation(MouseEvent event)
        Returns the preferred location to display the popup menu in this component's coordinate system. It is up to the look and feel to honor this property, some may choose to ignore it. If null, the look and feel will choose a suitable location.
        Parameters:
        event - the MouseEvent that triggered the popup to be shown, or null if the popup is not being shown as the result of a mouse event
        Returns:
        location to display the JPopupMenu, or null
        Since:
        1.5

      • createToolTip

        public JToolTip createToolTip()
        Returns the instance of JToolTip that should be used to display the tooltip. Components typically would not override this method, but it can be used to cause different tooltips to be displayed differently.
        Returns:
        the JToolTip used to display this toolTip

      • scrollRectToVisible

        public void scrollRectToVisible(Rectangle aRect)
        Forwards the scrollRectToVisible() message to the JComponent's parent. Components that can service the request, such as JViewport, override this method and perform the scrolling.
        Parameters:
        aRect - the visible Rectangle
        See Also:
        JViewport

      • setAutoscrolls

        public void setAutoscrolls(boolean autoscrolls)
        Sets the autoscrolls property. If true mouse dragged events will be synthetically generated when the mouse is dragged outside of the component's bounds and mouse motion has paused (while the button continues to be held down). The synthetic events make it appear that the drag gesture has resumed in the direction established when the component's boundary was crossed. Components that support autoscrolling must handle mouseDragged events by calling scrollRectToVisible with a rectangle that contains the mouse event's location. All of the Swing components that support item selection and are typically displayed in a JScrollPane (JTable, JList, JTree, JTextArea, and JEditorPane) already handle mouse dragged events in this way. To enable autoscrolling in any other component, add a mouse motion listener that calls scrollRectToVisible. For example, given a JPanel, myPanel: 
         MouseMotionListener doScrollRectToVisible = new MouseMotionAdapter() {
     public void mouseDragged(MouseEvent e) {
        Rectangle r = new Rectangle(e.getX(), e.getY(), 1, 1);
        ((JPanel)e.getSource()).scrollRectToVisible(r);
    }
 };
 myPanel.addMouseMotionListener(doScrollRectToVisible);
        The default value of the autoScrolls property is false.
        Parameters:
        autoscrolls - if true, synthetic mouse dragged events are generated when the mouse is dragged outside of a component's bounds and the mouse button continues to be held down; otherwise false
        See Also:
        getAutoscrolls(), JViewport, JScrollPane

      • getAutoscrolls

        public boolean getAutoscrolls()
        Gets the autoscrolls property.
        Returns:
        the value of the autoscrolls property
        See Also:
        JViewport, setAutoscrolls(boolean)

      • setTransferHandler

        public void setTransferHandler(TransferHandler newHandler)
        Sets the TransferHandler, which provides support for transfer of data into and out of this component via cut/copy/paste and drag and drop. This may be null if the component does not support data transfer operations.

        If the new TransferHandler is not null, this method also installs a new DropTarget on the component to activate drop handling through the TransferHandler and activate any built-in support (such as calculating and displaying potential drop locations). If you do not wish for this component to respond in any way to drops, you can disable drop support entirely either by removing the drop target (setDropTarget(null)) or by de-activating it (getDropTaget().setActive(false)).

        If the new TransferHandler is null, this method removes the drop target.

        Under two circumstances, this method does not modify the drop target: First, if the existing drop target on this component was explicitly set by the developer to a non-null value. Second, if the system property suppressSwingDropSupport is true. The default value for the system property is false.

        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:
        1.4
        See Also:
        TransferHandler, getTransferHandler()

      • enable

        @Deprecated
public void enable()
        Deprecated. As of JDK version 1.1, replaced by java.awt.Component.setEnabled(boolean).
        Overrides:
        enable in class Component

      • disable

        @Deprecated
public void disable()
        Deprecated. As of JDK version 1.1, replaced by java.awt.Component.setEnabled(boolean).
        Overrides:
        disable in class Component

      • getAccessibleContext

        public AccessibleContext getAccessibleContext()
        Returns the AccessibleContext associated with this JComponent. The method implemented by this base class returns null. Classes that extend JComponent should implement this method to return the AccessibleContext associated with the subclass.
        Overrides:
        getAccessibleContext in class Component
        Returns:
        the AccessibleContext of this JComponent

      • getClientProperty

        public final Object getClientProperty(Object key)
        Returns the value of the property with the specified key. Only properties added with putClientProperty will return a non-null value.
        Parameters:
        key - the being queried
        Returns:
        the value of this property or null
        See Also:
        putClientProperty(java.lang.Object, java.lang.Object)

      • putClientProperty

        public final void putClientProperty(Object key,
                     Object value)
        Adds an arbitrary key/value "client property" to this component.

        The get/putClientProperty methods provide access to a small per-instance hashtable. Callers can use get/putClientProperty to annotate components that were created by another module. For example, a layout manager might store per child constraints this way. For example: 

         componentA.putClientProperty("to the left of", componentB);
        If value is null this method will remove the property. Changes to client properties are reported with PropertyChange events. The name of the property (for the sake of PropertyChange events) is key.toString().

        The clientProperty dictionary is not intended to support large scale extensions to JComponent nor should be it considered an alternative to subclassing when designing a new component.

        Parameters:
        key - the new client property key
        value - the new client property value; if null this method will remove the property
        See Also:
        getClientProperty(java.lang.Object), Container.addPropertyChangeListener(java.beans.PropertyChangeListener)

      • isLightweightComponent

        public static boolean isLightweightComponent(Component c)
        Returns true if this component is lightweight, that is, if it doesn't have a native window system peer.
        Returns:
        true if this component is lightweight

      • reshape

        @Deprecated
public 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.

        Overrides:
        reshape in class Component
        Parameters:
        x - the new horizontal location
        y - the new vertical location
        w - the new width
        h - the new height
        See Also:
        Component.setBounds(int, int, int, int)

      • getBounds

        public Rectangle getBounds(Rectangle rv)
        Stores the bounds of this component into "return value" rv and returns rv. If rv is null a new Rectangle is allocated. This version of getBounds is useful if the caller wants to avoid allocating a new Rectangle object on the heap.
        Overrides:
        getBounds in class Component
        Parameters:
        rv - the return value, modified to the component's bounds
        Returns:
        rv; if rv is null return a newly created Rectangle with this component's bounds

      • getSize

        public Dimension getSize(Dimension rv)
        Stores the width/height of this component into "return value" rv and returns rv. If rv is null a new Dimension object is allocated. This version of getSize is useful if the caller wants to avoid allocating a new Dimension object on the heap.
        Overrides:
        getSize in class Component
        Parameters:
        rv - the return value, modified to the component's size
        Returns:
        rv

      • getLocation

        public Point getLocation(Point rv)
        Stores the x,y origin of this component into "return value" rv and returns rv. If rv is null a new Point is allocated. This version of getLocation is useful if the caller wants to avoid allocating a new Point object on the heap.
        Overrides:
        getLocation in class Component
        Parameters:
        rv - the return value, modified to the component's location
        Returns:
        rv

      • getX

        public int getX()
        Returns the current x coordinate of the component's origin. This method is preferable to writing component.getBounds().x, or component.getLocation().x because it doesn't cause any heap allocations.
        Overrides:
        getX in class Component
        Returns:
        the current x coordinate of the component's origin

      • getY

        public int getY()
        Returns the current y coordinate of the component's origin. This method is preferable to writing component.getBounds().y, or component.getLocation().y because it doesn't cause any heap allocations.
        Overrides:
        getY in class Component
        Returns:
        the current y coordinate of the component's origin

      • getWidth

        public int getWidth()
        Returns the current width of this component. This method is preferable to writing component.getBounds().width, or component.getSize().width because it doesn't cause any heap allocations.
        Overrides:
        getWidth in class Component
        Returns:
        the current width of this component

      • getHeight

        public int getHeight()
        Returns the current height of this component. This method is preferable to writing component.getBounds().height, or component.getSize().height because it doesn't cause any heap allocations.
        Overrides:
        getHeight in class Component
        Returns:
        the current height of this component

      • isOpaque

        public boolean isOpaque()
        Returns true if this component is completely opaque.

        An opaque component paints every pixel within its rectangular bounds. A non-opaque component paints only a subset of its pixels or none at all, allowing the pixels underneath it to "show through". Therefore, a component that does not fully paint its pixels provides a degree of transparency.

        Subclasses that guarantee to always completely paint their contents should override this method and return true.

        Overrides:
        isOpaque in class Component
        Returns:
        true if this component is completely opaque
        See Also:
        setOpaque(boolean)

      • setOpaque

        public void setOpaque(boolean isOpaque)
        If true the component paints every pixel within its bounds. Otherwise, the component may not paint some or all of its pixels, allowing the underlying pixels to show through.

        The default value of this property is false for JComponent. However, the default value for this property on most standard JComponent subclasses (such as JButton and JTree) is look-and-feel dependent.

        Parameters:
        isOpaque - true if this component should be opaque
        See Also:
        isOpaque()

      • computeVisibleRect

        public 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. The return value is stored in visibleRect.
        Parameters:
        visibleRect - a Rectangle computed as the intersection of all visible rectangles for this component and all of its ancestors -- this is the return value for this method
        See Also:
        getVisibleRect()

      • getVisibleRect

        public 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.
        Returns:
        the visible rectangle

      • firePropertyChange

        public void firePropertyChange(String propertyName,
                      boolean oldValue,
                      boolean newValue)
        Support for reporting bound property changes for boolean properties. This method can be called when a bound property has changed and it will send the appropriate PropertyChangeEvent to any registered PropertyChangeListeners.
        Overrides:
        firePropertyChange in class Component
        Parameters:
        propertyName - the property whose value has changed
        oldValue - the property's previous value
        newValue - the property's new value

      • firePropertyChange

        public void firePropertyChange(String propertyName,
                      int oldValue,
                      int newValue)
        Support for reporting bound property changes for integer properties. This method can be called when a bound property has changed and it will send the appropriate PropertyChangeEvent to any registered PropertyChangeListeners.
        Overrides:
        firePropertyChange in class Component
        Parameters:
        propertyName - the property whose value has changed
        oldValue - the property's previous value
        newValue - the property's new value

      • fireVetoableChange

        protected void fireVetoableChange(String propertyName,
                      Object oldValue,
                      Object newValue)
                           throws PropertyVetoException
        Supports reporting constrained property changes. This method can be called when a constrained property has changed and it will send the appropriate PropertyChangeEvent to any registered VetoableChangeListeners.
        Parameters:
        propertyName - the name of the property that was listened on
        oldValue - the old value of the property
        newValue - the new value of the property
        Throws:
        PropertyVetoException - when the attempt to set the property is vetoed by the component

      • addVetoableChangeListener

        public void addVetoableChangeListener(VetoableChangeListener listener)
        Adds a VetoableChangeListener to the listener list. The listener is registered for all properties.
        Parameters:
        listener - the VetoableChangeListener to be added

      • removeVetoableChangeListener

        public void removeVetoableChangeListener(VetoableChangeListener listener)
        Removes a VetoableChangeListener from the listener list. This removes a VetoableChangeListener that was registered for all properties.
        Parameters:
        listener - the VetoableChangeListener to be removed

      • getTopLevelAncestor

        public 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.
        Returns:
        the top-level Container that this component is in, or null if not in any container

      • addAncestorListener

        public 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. Events are also sent when the component or its ancestors are added or removed from the containment hierarchy.
        Parameters:
        listener - the AncestorListener to register
        See Also:
        AncestorEvent

      • getListeners

        public <T extends EventListener> T[] getListeners(Class<T> listenerType)
        Returns an array of all the objects currently registered as FooListeners upon this JComponent. FooListeners are registered using the addFooListener method.

        You can specify the listenerType argument with a class literal, such as FooListener.class. For example, you can query a JComponent c for its mouse listeners with the following code: 

        MouseListener[] mls = (MouseListener[])(c.getListeners(MouseListener.class));
        If no such listeners exist, this method returns an empty array.
        Overrides:
        getListeners in class Container
        Parameters:
        listenerType - the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener
        Returns:
        an array of all objects registered as FooListeners on this component, or an empty array if no such listeners have been added
        Throws:
        ClassCastException - if listenerType doesn't specify a class or interface that implements java.util.EventListener
        Since:
        1.3
        See Also:
        getVetoableChangeListeners(), getAncestorListeners()

      • revalidate

        public void revalidate()
        Supports deferred automatic layout.

        Calls invalidate and then adds this component's validateRoot to a list of components that need to be validated. Validation will occur after all currently pending events have been dispatched. In other words after this method is called, the first validateRoot (if any) found when walking up the containment hierarchy of this component will be validated. By default, JRootPane, JScrollPane, and JTextField return true from isValidateRoot.

        This method will automatically be called on this component when a property value changes such that size, location, or internal layout of this component has been affected. This automatic updating differs from the AWT because programs generally no longer need to invoke validate to get the contents of the GUI to update.

        Overrides:
        revalidate in class Component
        See Also:
        Component.invalidate(), Container.validate(), isValidateRoot(), RepaintManager.addInvalidComponent(javax.swing.JComponent)

      • isOptimizedDrawingEnabled

        public boolean isOptimizedDrawingEnabled()
        Returns true if this component tiles its children -- that is, if it can guarantee that the children will not overlap. The repainting system is substantially more efficient in this common case. JComponent subclasses that can't make this guarantee, such as JLayeredPane, should override this method to return false.
        Returns:
        always returns true

      • paintImmediately

        public 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.

        It's rarely necessary to call this method. In most cases it's more efficient to call repaint, which defers the actual painting and can collapse redundant requests into a single paint call. This method is useful if one needs to update the display while the current event is being dispatched.

        This method is to be overridden when the dirty region needs to be changed for components that are painting origins.

        Parameters:
        x - the x value of the region to be painted
        y - the y value of the region to be painted
        w - the width of the region to be painted
        h - the height of the region to be painted
        See Also:
        repaint(long, int, int, int, int), isPaintingOrigin()

      • paintImmediately

        public void paintImmediately(Rectangle r)
        Paints the specified region now.
        Parameters:
        r - a Rectangle containing the region to be painted

      • setDoubleBuffered

        public void setDoubleBuffered(boolean aFlag)
        Sets whether this component should use a buffer to paint. If set to true, all the drawing from this component will be done in an offscreen painting buffer. The offscreen painting buffer will the be copied onto the screen. If a Component is buffered and one of its ancestor is also buffered, the ancestor buffer will be used.
        Parameters:
        aFlag - if true, set this component to be double buffered

      • isDoubleBuffered

        public boolean isDoubleBuffered()
        Returns whether this component should use a buffer to paint.
        Overrides:
        isDoubleBuffered in class Component
        Returns:
        true if this component is double buffered, otherwise false

      • getRootPane

        public JRootPane getRootPane()
        Returns the JRootPane ancestor for this component.
        Returns:
        the JRootPane that contains this component, or null if no JRootPane is found

      • paramString

        protected String paramString()
        Returns a string representation of this JComponent. 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 Container
        Returns:
        a string representation of this JComponent

Document created the 11/06/2005, last modified the 04/03/2020
Source of the printed document:https://www.gaudry.be/en/java-api-rf-javax/swing/jcomponent.html

The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.

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