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Java java.awt Class KeyboardFocusManager（JDK8）

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Java™ Platform
Standard Ed. 8
java.awt

Class KeyboardFocusManager

  • All Implemented Interfaces:
    KeyEventDispatcher, KeyEventPostProcessor
    Direct Known Subclasses:
    DefaultKeyboardFocusManager 

    public abstract class KeyboardFocusManager
extends Object
implements KeyEventDispatcher, KeyEventPostProcessor
    The KeyboardFocusManager is responsible for managing the active and focused Windows, and the current focus owner. The focus owner is defined as the Component in an application that will typically receive all KeyEvents generated by the user. The focused Window is the Window that is, or contains, the focus owner. Only a Frame or a Dialog can be the active Window. The native windowing system may denote the active Window or its children with special decorations, such as a highlighted title bar. The active Window is always either the focused Window, or the first Frame or Dialog that is an owner of the focused Window.

    The KeyboardFocusManager is both a centralized location for client code to query for the focus owner and initiate focus changes, and an event dispatcher for all FocusEvents, WindowEvents related to focus, and KeyEvents.

    Some browsers partition applets in different code bases into separate contexts, and establish walls between these contexts. In such a scenario, there will be one KeyboardFocusManager per context. Other browsers place all applets into the same context, implying that there will be only a single, global KeyboardFocusManager for all applets. This behavior is implementation-dependent. Consult your browser's documentation for more information. No matter how many contexts there may be, however, there can never be more than one focus owner, focused Window, or active Window, per ClassLoader.

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

    Since:
    1.4
    See Also:
    Window, Frame, Dialog, FocusEvent, WindowEvent, KeyEvent

    • Constructor Detail

      • KeyboardFocusManager

        public KeyboardFocusManager()
        Initializes a KeyboardFocusManager.

    • Method Detail

      • setCurrentKeyboardFocusManager

        public static void setCurrentKeyboardFocusManager(KeyboardFocusManager newManager)
                                           throws SecurityException
        Sets the current KeyboardFocusManager instance for the calling thread's context. If null is specified, then the current KeyboardFocusManager is replaced with a new instance of DefaultKeyboardFocusManager.

        If a SecurityManager is installed, the calling thread must be granted the AWTPermission "replaceKeyboardFocusManager" in order to replace the the current KeyboardFocusManager. If this permission is not granted, this method will throw a SecurityException, and the current KeyboardFocusManager will be unchanged.

        Parameters:
        newManager - the new KeyboardFocusManager for this thread's context
        Throws:
        SecurityException - if the calling thread does not have permission to replace the current KeyboardFocusManager
        See Also:
        getCurrentKeyboardFocusManager(), DefaultKeyboardFocusManager

      • getFocusOwner

        public Component getFocusOwner()
        Returns the focus owner, if the focus owner is in the same context as the calling thread. The focus owner is defined as the Component in an application that will typically receive all KeyEvents generated by the user. KeyEvents which map to the focus owner's focus traversal keys will not be delivered if focus traversal keys are enabled for the focus owner. In addition, KeyEventDispatchers may retarget or consume KeyEvents before they reach the focus owner.
        Returns:
        the focus owner, or null if the focus owner is not a member of the calling thread's context
        See Also:
        getGlobalFocusOwner(), setGlobalFocusOwner(java.awt.Component)

      • getGlobalFocusOwner

        protected Component getGlobalFocusOwner()
                                 throws SecurityException
        Returns the focus owner, even if the calling thread is in a different context than the focus owner. The focus owner is defined as the Component in an application that will typically receive all KeyEvents generated by the user. KeyEvents which map to the focus owner's focus traversal keys will not be delivered if focus traversal keys are enabled for the focus owner. In addition, KeyEventDispatchers may retarget or consume KeyEvents before they reach the focus owner.

        This method will throw a SecurityException if this KeyboardFocusManager is not the current KeyboardFocusManager for the calling thread's context.

        Returns:
        the focus owner
        Throws:
        SecurityException - if this KeyboardFocusManager is not the current KeyboardFocusManager for the calling thread's context and if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        getFocusOwner(), setGlobalFocusOwner(java.awt.Component)

      • setGlobalFocusOwner

        protected void setGlobalFocusOwner(Component focusOwner)
                            throws SecurityException
        Sets the focus owner. The operation will be cancelled if the Component is not focusable. The focus owner is defined as the Component in an application that will typically receive all KeyEvents generated by the user. KeyEvents which map to the focus owner's focus traversal keys will not be delivered if focus traversal keys are enabled for the focus owner. In addition, KeyEventDispatchers may retarget or consume KeyEvents before they reach the focus owner.

        This method does not actually set the focus to the specified Component. It merely stores the value to be subsequently returned by getFocusOwner(). Use Component.requestFocus() or Component.requestFocusInWindow() to change the focus owner, subject to platform limitations.

        Parameters:
        focusOwner - the focus owner
        Throws:
        SecurityException - if this KeyboardFocusManager is not the current KeyboardFocusManager for the calling thread's context and if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        getFocusOwner(), getGlobalFocusOwner(), Component.requestFocus(), Component.requestFocusInWindow(), Component.isFocusable()

      • clearFocusOwner

        public void clearFocusOwner()
        Clears the focus owner at both the Java and native levels if the focus owner exists and resides in the same context as the calling thread, otherwise the method returns silently.

        The focus owner component will receive a permanent FOCUS_LOST event. After this operation completes, the native windowing system will discard all user-generated KeyEvents until the user selects a new Component to receive focus, or a Component is given focus explicitly via a call to requestFocus(). This operation does not change the focused or active Windows.

        Since:
        1.8
        See Also:
        Component.requestFocus(), FocusEvent.FOCUS_LOST

      • clearGlobalFocusOwner

        public void clearGlobalFocusOwner()
                           throws SecurityException
        Clears the global focus owner at both the Java and native levels. If there exists a focus owner, that Component will receive a permanent FOCUS_LOST event. After this operation completes, the native windowing system will discard all user-generated KeyEvents until the user selects a new Component to receive focus, or a Component is given focus explicitly via a call to requestFocus(). This operation does not change the focused or active Windows.

        If a SecurityManager is installed, the calling thread must be granted the "replaceKeyboardFocusManager" AWTPermission. If this permission is not granted, this method will throw a SecurityException, and the current focus owner will not be cleared.

        This method is intended to be used only by KeyboardFocusManager set as current KeyboardFocusManager for the calling thread's context. It is not for general client use.

        Throws:
        SecurityException - if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        clearFocusOwner(), Component.requestFocus(), FocusEvent.FOCUS_LOST

      • getPermanentFocusOwner

        public Component getPermanentFocusOwner()
        Returns the permanent focus owner, if the permanent focus owner is in the same context as the calling thread. The permanent focus owner is defined as the last Component in an application to receive a permanent FOCUS_GAINED event. The focus owner and permanent focus owner are equivalent unless a temporary focus change is currently in effect. In such a situation, the permanent focus owner will again be the focus owner when the temporary focus change ends.
        Returns:
        the permanent focus owner, or null if the permanent focus owner is not a member of the calling thread's context
        See Also:
        getGlobalPermanentFocusOwner(), setGlobalPermanentFocusOwner(java.awt.Component)

      • getGlobalPermanentFocusOwner

        protected Component getGlobalPermanentFocusOwner()
                                          throws SecurityException
        Returns the permanent focus owner, even if the calling thread is in a different context than the permanent focus owner. The permanent focus owner is defined as the last Component in an application to receive a permanent FOCUS_GAINED event. The focus owner and permanent focus owner are equivalent unless a temporary focus change is currently in effect. In such a situation, the permanent focus owner will again be the focus owner when the temporary focus change ends.
        Returns:
        the permanent focus owner
        Throws:
        SecurityException - if this KeyboardFocusManager is not the current KeyboardFocusManager for the calling thread's context and if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        getPermanentFocusOwner(), setGlobalPermanentFocusOwner(java.awt.Component)

      • setGlobalPermanentFocusOwner

        protected void setGlobalPermanentFocusOwner(Component permanentFocusOwner)
                                     throws SecurityException
        Sets the permanent focus owner. The operation will be cancelled if the Component is not focusable. The permanent focus owner is defined as the last Component in an application to receive a permanent FOCUS_GAINED event. The focus owner and permanent focus owner are equivalent unless a temporary focus change is currently in effect. In such a situation, the permanent focus owner will again be the focus owner when the temporary focus change ends.

        This method does not actually set the focus to the specified Component. It merely stores the value to be subsequently returned by getPermanentFocusOwner(). Use Component.requestFocus() or Component.requestFocusInWindow() to change the focus owner, subject to platform limitations.

        Parameters:
        permanentFocusOwner - the permanent focus owner
        Throws:
        SecurityException - if this KeyboardFocusManager is not the current KeyboardFocusManager for the calling thread's context and if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        getPermanentFocusOwner(), getGlobalPermanentFocusOwner(), Component.requestFocus(), Component.requestFocusInWindow(), Component.isFocusable()

      • getFocusedWindow

        public Window getFocusedWindow()
        Returns the focused Window, if the focused Window is in the same context as the calling thread. The focused Window is the Window that is or contains the focus owner.
        Returns:
        the focused Window, or null if the focused Window is not a member of the calling thread's context
        See Also:
        getGlobalFocusedWindow(), setGlobalFocusedWindow(java.awt.Window)

      • getGlobalFocusedWindow

        protected Window getGlobalFocusedWindow()
                                 throws SecurityException
        Returns the focused Window, even if the calling thread is in a different context than the focused Window. The focused Window is the Window that is or contains the focus owner.
        Returns:
        the focused Window
        Throws:
        SecurityException - if this KeyboardFocusManager is not the current KeyboardFocusManager for the calling thread's context and if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        getFocusedWindow(), setGlobalFocusedWindow(java.awt.Window)

      • setGlobalFocusedWindow

        protected void setGlobalFocusedWindow(Window focusedWindow)
                               throws SecurityException
        Sets the focused Window. The focused Window is the Window that is or contains the focus owner. The operation will be cancelled if the specified Window to focus is not a focusable Window.

        This method does not actually change the focused Window as far as the native windowing system is concerned. It merely stores the value to be subsequently returned by getFocusedWindow(). Use Component.requestFocus() or Component.requestFocusInWindow() to change the focused Window, subject to platform limitations.

        Parameters:
        focusedWindow - the focused Window
        Throws:
        SecurityException - if this KeyboardFocusManager is not the current KeyboardFocusManager for the calling thread's context and if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        getFocusedWindow(), getGlobalFocusedWindow(), Component.requestFocus(), Component.requestFocusInWindow(), Window.isFocusableWindow()

      • getActiveWindow

        public Window getActiveWindow()
        Returns the active Window, if the active Window is in the same context as the calling thread. Only a Frame or a Dialog can be the active Window. The native windowing system may denote the active Window or its children with special decorations, such as a highlighted title bar. The active Window is always either the focused Window, or the first Frame or Dialog that is an owner of the focused Window.
        Returns:
        the active Window, or null if the active Window is not a member of the calling thread's context
        See Also:
        getGlobalActiveWindow(), setGlobalActiveWindow(java.awt.Window)

      • getGlobalActiveWindow

        protected Window getGlobalActiveWindow()
                                throws SecurityException
        Returns the active Window, even if the calling thread is in a different context than the active Window. Only a Frame or a Dialog can be the active Window. The native windowing system may denote the active Window or its children with special decorations, such as a highlighted title bar. The active Window is always either the focused Window, or the first Frame or Dialog that is an owner of the focused Window.
        Returns:
        the active Window
        Throws:
        SecurityException - if this KeyboardFocusManager is not the current KeyboardFocusManager for the calling thread's context and if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        getActiveWindow(), setGlobalActiveWindow(java.awt.Window)

      • setGlobalActiveWindow

        protected void setGlobalActiveWindow(Window activeWindow)
                              throws SecurityException
        Sets the active Window. Only a Frame or a Dialog can be the active Window. The native windowing system may denote the active Window or its children with special decorations, such as a highlighted title bar. The active Window is always either the focused Window, or the first Frame or Dialog that is an owner of the focused Window.

        This method does not actually change the active Window as far as the native windowing system is concerned. It merely stores the value to be subsequently returned by getActiveWindow(). Use Component.requestFocus() or Component.requestFocusInWindow()to change the active Window, subject to platform limitations.

        Parameters:
        activeWindow - the active Window
        Throws:
        SecurityException - if this KeyboardFocusManager is not the current KeyboardFocusManager for the calling thread's context and if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        getActiveWindow(), getGlobalActiveWindow(), Component.requestFocus(), Component.requestFocusInWindow()

      • setDefaultFocusTraversalKeys

        public void setDefaultFocusTraversalKeys(int id,
                                         Set<? extends AWTKeyStroke> keystrokes)
        Sets the default focus traversal keys for a given traversal operation. This traversal key Set will be in effect on all Windows that have no such Set of their own explicitly defined. This Set will also be inherited, recursively, by any child Component of those Windows that has no such Set of its own explicitly defined.

        The default values for the default focus traversal keys are implementation-dependent. Sun recommends that all implementations for a particular native platform use the same default values. The recommendations for Windows and Unix are listed below. These recommendations are used in the Sun AWT implementations.

        Identifier Meaning Default
        KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS Normal forward keyboard traversal TAB on KEY_PRESSED, CTRL-TAB on KEY_PRESSED
        KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS Normal reverse keyboard traversal SHIFT-TAB on KEY_PRESSED, CTRL-SHIFT-TAB on KEY_PRESSED
        KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS Go up one focus traversal cycle none
        KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS Go down one focus traversal cycle none
        To disable a traversal key, use an empty Set; Collections.EMPTY_SET is recommended.

        Using the AWTKeyStroke API, client code can specify on which of two specific KeyEvents, KEY_PRESSED or KEY_RELEASED, the focus traversal operation will occur. Regardless of which KeyEvent is specified, however, all KeyEvents related to the focus traversal key, including the associated KEY_TYPED event, will be consumed, and will not be dispatched to any Component. It is a runtime error to specify a KEY_TYPED event as mapping to a focus traversal operation, or to map the same event to multiple default focus traversal operations.

        This method may throw a ClassCastException if any Object in keystrokes is not an AWTKeyStroke.

        Parameters:
        id - one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS
        keystrokes - the Set of AWTKeyStrokes for the specified operation
        Throws:
        IllegalArgumentException - if id is not one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS, or if keystrokes is null, or if keystrokes contains null, or if any keystroke represents a KEY_TYPED event, or if any keystroke already maps to another default focus traversal operation
        See Also:
        getDefaultFocusTraversalKeys(int), Component.setFocusTraversalKeys(int, java.util.Set<? extends java.awt.AWTKeyStroke>), Component.getFocusTraversalKeys(int)

      • getDefaultFocusTraversalKeys

        public Set<AWTKeyStroke> getDefaultFocusTraversalKeys(int id)
        Returns a Set of default focus traversal keys for a given traversal operation. This traversal key Set will be in effect on all Windows that have no such Set of their own explicitly defined. This Set will also be inherited, recursively, by any child Component of those Windows that has no such Set of its own explicitly defined. (See setDefaultFocusTraversalKeys for a full description of each operation.)
        Parameters:
        id - one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS
        Returns:
        the Set of AWTKeyStrokes for the specified operation; the Set will be unmodifiable, and may be empty; null will never be returned
        Throws:
        IllegalArgumentException - if id is not one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS
        See Also:
        setDefaultFocusTraversalKeys(int, java.util.Set<? extends java.awt.AWTKeyStroke>), Component.setFocusTraversalKeys(int, java.util.Set<? extends java.awt.AWTKeyStroke>), Component.getFocusTraversalKeys(int)

      • getCurrentFocusCycleRoot

        public Container getCurrentFocusCycleRoot()
        Returns the current focus cycle root, if the current focus cycle root is in the same context as the calling thread. If the focus owner is itself a focus cycle root, then it may be ambiguous as to which Components represent the next and previous Components to focus during normal focus traversal. In that case, the current focus cycle root is used to differentiate among the possibilities.

        This method is intended to be used only by KeyboardFocusManagers and focus implementations. It is not for general client use.

        Returns:
        the current focus cycle root, or null if the current focus cycle root is not a member of the calling thread's context
        See Also:
        getGlobalCurrentFocusCycleRoot(), setGlobalCurrentFocusCycleRoot(java.awt.Container)

      • getGlobalCurrentFocusCycleRoot

        protected Container getGlobalCurrentFocusCycleRoot()
                                            throws SecurityException
        Returns the current focus cycle root, even if the calling thread is in a different context than the current focus cycle root. If the focus owner is itself a focus cycle root, then it may be ambiguous as to which Components represent the next and previous Components to focus during normal focus traversal. In that case, the current focus cycle root is used to differentiate among the possibilities.
        Returns:
        the current focus cycle root, or null if the current focus cycle root is not a member of the calling thread's context
        Throws:
        SecurityException - if this KeyboardFocusManager is not the current KeyboardFocusManager for the calling thread's context and if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        getCurrentFocusCycleRoot(), setGlobalCurrentFocusCycleRoot(java.awt.Container)

      • setGlobalCurrentFocusCycleRoot

        public void setGlobalCurrentFocusCycleRoot(Container newFocusCycleRoot)
                                    throws SecurityException
        Sets the current focus cycle root. If the focus owner is itself a focus cycle root, then it may be ambiguous as to which Components represent the next and previous Components to focus during normal focus traversal. In that case, the current focus cycle root is used to differentiate among the possibilities.

        If a SecurityManager is installed, the calling thread must be granted the "replaceKeyboardFocusManager" AWTPermission. If this permission is not granted, this method will throw a SecurityException, and the current focus cycle root will not be changed.

        This method is intended to be used only by KeyboardFocusManagers and focus implementations. It is not for general client use.

        Parameters:
        newFocusCycleRoot - the new focus cycle root
        Throws:
        SecurityException - if the calling thread does not have "replaceKeyboardFocusManager" permission
        See Also:
        getCurrentFocusCycleRoot(), getGlobalCurrentFocusCycleRoot()

      • addPropertyChangeListener

        public void addPropertyChangeListener(PropertyChangeListener listener)
        Adds a PropertyChangeListener to the listener list. The listener is registered for all bound properties of this class, including the following:
        • whether the KeyboardFocusManager is currently managing focus for this application or applet's browser context ("managingFocus")
        • the focus owner ("focusOwner")
        • the permanent focus owner ("permanentFocusOwner")
        • the focused Window ("focusedWindow")
        • the active Window ("activeWindow")
        • the default focus traversal policy ("defaultFocusTraversalPolicy")
        • the Set of default FORWARD_TRAVERSAL_KEYS ("forwardDefaultFocusTraversalKeys")
        • the Set of default BACKWARD_TRAVERSAL_KEYS ("backwardDefaultFocusTraversalKeys")
        • the Set of default UP_CYCLE_TRAVERSAL_KEYS ("upCycleDefaultFocusTraversalKeys")
        • the Set of default DOWN_CYCLE_TRAVERSAL_KEYS ("downCycleDefaultFocusTraversalKeys")
        • the current focus cycle root ("currentFocusCycleRoot")
        If listener is null, no exception is thrown and no action is performed.
        Parameters:
        listener - the PropertyChangeListener to be added
        See Also:
        removePropertyChangeListener(java.beans.PropertyChangeListener), getPropertyChangeListeners(), addPropertyChangeListener(java.lang.String,java.beans.PropertyChangeListener)

      • addPropertyChangeListener

        public void addPropertyChangeListener(String propertyName,
                                      PropertyChangeListener listener)
        Adds a PropertyChangeListener to the listener list for a specific property. The specified property may be user-defined, or one of the following:
        • whether the KeyboardFocusManager is currently managing focus for this application or applet's browser context ("managingFocus")
        • the focus owner ("focusOwner")
        • the permanent focus owner ("permanentFocusOwner")
        • the focused Window ("focusedWindow")
        • the active Window ("activeWindow")
        • the default focus traversal policy ("defaultFocusTraversalPolicy")
        • the Set of default FORWARD_TRAVERSAL_KEYS ("forwardDefaultFocusTraversalKeys")
        • the Set of default BACKWARD_TRAVERSAL_KEYS ("backwardDefaultFocusTraversalKeys")
        • the Set of default UP_CYCLE_TRAVERSAL_KEYS ("upCycleDefaultFocusTraversalKeys")
        • the Set of default DOWN_CYCLE_TRAVERSAL_KEYS ("downCycleDefaultFocusTraversalKeys")
        • the current focus cycle root ("currentFocusCycleRoot")
        If listener is null, no exception is thrown and no action is performed.
        Parameters:
        propertyName - one of the property names listed above
        listener - the PropertyChangeListener to be added
        See Also:
        addPropertyChangeListener(java.beans.PropertyChangeListener), removePropertyChangeListener(java.lang.String,java.beans.PropertyChangeListener), getPropertyChangeListeners(java.lang.String)

      • firePropertyChange

        protected void firePropertyChange(String propertyName,
                                  Object oldValue,
                                  Object newValue)
        Fires a PropertyChangeEvent in response to a change in a bound property. The event will be delivered to all registered PropertyChangeListeners. No event will be delivered if oldValue and newValue are the same.
        Parameters:
        propertyName - the name of the property that 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
        Fires a PropertyChangeEvent in response to a change in a vetoable property. The event will be delivered to all registered VetoableChangeListeners. If a VetoableChangeListener throws a PropertyVetoException, a new event is fired reverting all VetoableChangeListeners to the old value and the exception is then rethrown. No event will be delivered if oldValue and newValue are the same.
        Parameters:
        propertyName - the name of the property that has changed
        oldValue - the property's previous value
        newValue - the property's new value
        Throws:
        PropertyVetoException - if a VetoableChangeListener threw PropertyVetoException

      • addKeyEventDispatcher

        public void addKeyEventDispatcher(KeyEventDispatcher dispatcher)
        Adds a KeyEventDispatcher to this KeyboardFocusManager's dispatcher chain. This KeyboardFocusManager will request that each KeyEventDispatcher dispatch KeyEvents generated by the user before finally dispatching the KeyEvent itself. KeyEventDispatchers will be notified in the order in which they were added. Notifications will halt as soon as one KeyEventDispatcher returns true from its dispatchKeyEvent method. There is no limit to the total number of KeyEventDispatchers which can be added, nor to the number of times which a particular KeyEventDispatcher instance can be added.

        If a null dispatcher is specified, no action is taken and no exception is thrown.

        In a multithreaded application, KeyEventDispatcher behaves the same as other AWT listeners. See AWT Threading Issues for more details.

        Parameters:
        dispatcher - the KeyEventDispatcher to add to the dispatcher chain
        See Also:
        removeKeyEventDispatcher(java.awt.KeyEventDispatcher)

      • removeKeyEventDispatcher

        public void removeKeyEventDispatcher(KeyEventDispatcher dispatcher)
        Removes a KeyEventDispatcher which was previously added to this KeyboardFocusManager's dispatcher chain. This KeyboardFocusManager cannot itself be removed, unless it was explicitly re-registered via a call to addKeyEventDispatcher.

        If a null dispatcher is specified, if the specified dispatcher is not in the dispatcher chain, or if this KeyboardFocusManager is specified without having been explicitly re-registered, no action is taken and no exception is thrown.

        In a multithreaded application, KeyEventDispatcher behaves the same as other AWT listeners. See AWT Threading Issues for more details.

        Parameters:
        dispatcher - the KeyEventDispatcher to remove from the dispatcher chain
        See Also:
        addKeyEventDispatcher(java.awt.KeyEventDispatcher)

      • getKeyEventDispatchers

        protected List<KeyEventDispatcher> getKeyEventDispatchers()
        Returns this KeyboardFocusManager's KeyEventDispatcher chain as a List. The List will not include this KeyboardFocusManager unless it was explicitly re-registered via a call to addKeyEventDispatcher. If no other KeyEventDispatchers are registered, implementations are free to return null or a List of length 0. Client code should not assume one behavior over another, nor should it assume that the behavior, once established, will not change.
        Returns:
        a possibly null or empty List of KeyEventDispatchers
        See Also:
        addKeyEventDispatcher(java.awt.KeyEventDispatcher), removeKeyEventDispatcher(java.awt.KeyEventDispatcher)

      • addKeyEventPostProcessor

        public void addKeyEventPostProcessor(KeyEventPostProcessor processor)
        Adds a KeyEventPostProcessor to this KeyboardFocusManager's post- processor chain. After a KeyEvent has been dispatched to and handled by its target, KeyboardFocusManager will request that each KeyEventPostProcessor perform any necessary post-processing as part of the KeyEvent's final resolution. KeyEventPostProcessors will be notified in the order in which they were added; the current KeyboardFocusManager will be notified last. Notifications will halt as soon as one KeyEventPostProcessor returns true from its postProcessKeyEvent method. There is no limit to the the total number of KeyEventPostProcessors that can be added, nor to the number of times that a particular KeyEventPostProcessor instance can be added.

        If a null post-processor is specified, no action is taken and no exception is thrown.

        In a multithreaded application, KeyEventPostProcessor behaves the same as other AWT listeners. See AWT Threading Issues for more details.

        Parameters:
        processor - the KeyEventPostProcessor to add to the post-processor chain
        See Also:
        removeKeyEventPostProcessor(java.awt.KeyEventPostProcessor)

      • removeKeyEventPostProcessor

        public void removeKeyEventPostProcessor(KeyEventPostProcessor processor)
        Removes a previously added KeyEventPostProcessor from this KeyboardFocusManager's post-processor chain. This KeyboardFocusManager cannot itself be entirely removed from the chain. Only additional references added via addKeyEventPostProcessor can be removed.

        If a null post-processor is specified, if the specified post-processor is not in the post-processor chain, or if this KeyboardFocusManager is specified without having been explicitly added, no action is taken and no exception is thrown.

        In a multithreaded application, KeyEventPostProcessor behaves the same as other AWT listeners. See AWT Threading Issues for more details.

        Parameters:
        processor - the KeyEventPostProcessor to remove from the post- processor chain
        See Also:
        addKeyEventPostProcessor(java.awt.KeyEventPostProcessor)

      • getKeyEventPostProcessors

        protected List<KeyEventPostProcessor> getKeyEventPostProcessors()
        Returns this KeyboardFocusManager's KeyEventPostProcessor chain as a List. The List will not include this KeyboardFocusManager unless it was explicitly added via a call to addKeyEventPostProcessor. If no KeyEventPostProcessors are registered, implementations are free to return null or a List of length 0. Client code should not assume one behavior over another, nor should it assume that the behavior, once established, will not change.
        Returns:
        a possibly null or empty List of KeyEventPostProcessors
        See Also:
        addKeyEventPostProcessor(java.awt.KeyEventPostProcessor), removeKeyEventPostProcessor(java.awt.KeyEventPostProcessor)

      • dispatchEvent

        public abstract boolean dispatchEvent(AWTEvent e)
        This method is called by the AWT event dispatcher requesting that the current KeyboardFocusManager dispatch the specified event on its behalf. It is expected that all KeyboardFocusManagers will dispatch all FocusEvents, all WindowEvents related to focus, and all KeyEvents. These events should be dispatched based on the KeyboardFocusManager's notion of the focus owner and the focused and active Windows, sometimes overriding the source of the specified AWTEvent. Dispatching must be done using redispatchEvent to prevent the AWT event dispatcher from recursively requesting that the KeyboardFocusManager dispatch the event again. If this method returns false, then the AWT event dispatcher will attempt to dispatch the event itself.
        Parameters:
        e - the AWTEvent to be dispatched
        Returns:
        true if this method dispatched the event; false otherwise
        See Also:
        redispatchEvent(java.awt.Component, java.awt.AWTEvent), dispatchKeyEvent(java.awt.event.KeyEvent)

      • redispatchEvent

        public final void redispatchEvent(Component target,
                                  AWTEvent e)
        Redispatches an AWTEvent in such a way that the AWT event dispatcher will not recursively request that the KeyboardFocusManager, or any installed KeyEventDispatchers, dispatch the event again. Client implementations of dispatchEvent and client-defined KeyEventDispatchers must call redispatchEvent(target, e) instead of target.dispatchEvent(e) to dispatch an event.

        This method is intended to be used only by KeyboardFocusManagers and KeyEventDispatchers. It is not for general client use.

        Parameters:
        target - the Component to which the event should be dispatched
        e - the event to dispatch
        See Also:
        dispatchEvent(java.awt.AWTEvent), KeyEventDispatcher

      • dispatchKeyEvent

        public abstract boolean dispatchKeyEvent(KeyEvent e)
        Typically this method will be called by dispatchEvent if no other KeyEventDispatcher in the dispatcher chain dispatched the KeyEvent, or if no other KeyEventDispatchers are registered. If an implementation of this method returns false, dispatchEvent may try to dispatch the KeyEvent itself, or may simply return false. If true is returned, dispatchEvent should return true as well.
        Specified by:
        dispatchKeyEvent in interface KeyEventDispatcher
        Parameters:
        e - the KeyEvent which the current KeyboardFocusManager has requested that this KeyEventDispatcher dispatch
        Returns:
        true if the KeyEvent was dispatched; false otherwise
        See Also:
        dispatchEvent(java.awt.AWTEvent)

      • postProcessKeyEvent

        public abstract boolean postProcessKeyEvent(KeyEvent e)
        This method will be called by dispatchKeyEvent. By default, this method will handle any unconsumed KeyEvents that map to an AWT MenuShortcut by consuming the event and activating the shortcut.
        Specified by:
        postProcessKeyEvent in interface KeyEventPostProcessor
        Parameters:
        e - the KeyEvent to post-process
        Returns:
        true to indicate that no other KeyEventPostProcessor will be notified of the KeyEvent.
        See Also:
        dispatchKeyEvent(java.awt.event.KeyEvent), MenuShortcut

      • processKeyEvent

        public abstract void processKeyEvent(Component focusedComponent,
                                     KeyEvent e)
        This method initiates a focus traversal operation if and only if the KeyEvent represents a focus traversal key for the specified focusedComponent. It is expected that focusedComponent is the current focus owner, although this need not be the case. If it is not, focus traversal will nevertheless proceed as if focusedComponent were the current focus owner.
        Parameters:
        focusedComponent - the Component that will be the basis for a focus traversal operation if the specified event represents a focus traversal key for the Component
        e - the event that may represent a focus traversal key

      • enqueueKeyEvents

        protected abstract void enqueueKeyEvents(long after,
                                         Component untilFocused)
        Called by the AWT to notify the KeyboardFocusManager that it should delay dispatching of KeyEvents until the specified Component becomes the focus owner. If client code requests a focus change, and the AWT determines that this request might be granted by the native windowing system, then the AWT will call this method. It is the responsibility of the KeyboardFocusManager to delay dispatching of KeyEvents with timestamps later than the specified time stamp until the specified Component receives a FOCUS_GAINED event, or the AWT cancels the delay request by invoking dequeueKeyEvents or discardKeyEvents.
        Parameters:
        after - timestamp of current event, or the current, system time if the current event has no timestamp, or the AWT cannot determine which event is currently being handled
        untilFocused - Component which should receive a FOCUS_GAINED event before any pending KeyEvents
        See Also:
        dequeueKeyEvents(long, java.awt.Component), discardKeyEvents(java.awt.Component)

      • dequeueKeyEvents

        protected abstract void dequeueKeyEvents(long after,
                                         Component untilFocused)
        Called by the AWT to notify the KeyboardFocusManager that it should cancel delayed dispatching of KeyEvents. All KeyEvents which were enqueued because of a call to enqueueKeyEvents with the same timestamp and Component should be released for normal dispatching to the current focus owner. If the given timestamp is less than zero, the outstanding enqueue request for the given Component with the oldest timestamp (if any) should be cancelled.
        Parameters:
        after - the timestamp specified in the call to enqueueKeyEvents, or any value < 0
        untilFocused - the Component specified in the call to enqueueKeyEvents
        See Also:
        enqueueKeyEvents(long, java.awt.Component), discardKeyEvents(java.awt.Component)

      • discardKeyEvents

        protected abstract void discardKeyEvents(Component comp)
        Called by the AWT to notify the KeyboardFocusManager that it should cancel delayed dispatching of KeyEvents. All KeyEvents which were enqueued because of one or more calls to enqueueKeyEvents with the same Component should be discarded.
        Parameters:
        comp - the Component specified in one or more calls to enqueueKeyEvents
        See Also:
        enqueueKeyEvents(long, java.awt.Component), dequeueKeyEvents(long, java.awt.Component)

      • focusNextComponent

        public abstract void focusNextComponent(Component aComponent)
        Focuses the Component after aComponent, typically based on a FocusTraversalPolicy.
        Parameters:
        aComponent - the Component that is the basis for the focus traversal operation
        See Also:
        FocusTraversalPolicy

      • focusPreviousComponent

        public abstract void focusPreviousComponent(Component aComponent)
        Focuses the Component before aComponent, typically based on a FocusTraversalPolicy.
        Parameters:
        aComponent - the Component that is the basis for the focus traversal operation
        See Also:
        FocusTraversalPolicy

      • upFocusCycle

        public abstract void upFocusCycle(Component aComponent)
        Moves the focus up one focus traversal cycle. Typically, the focus owner is set to aComponent's focus cycle root, and the current focus cycle root is set to the new focus owner's focus cycle root. If, however, aComponent's focus cycle root is a Window, then typically the focus owner is set to the Window's default Component to focus, and the current focus cycle root is unchanged.
        Parameters:
        aComponent - the Component that is the basis for the focus traversal operation

      • downFocusCycle

        public abstract void downFocusCycle(Container aContainer)
        Moves the focus down one focus traversal cycle. Typically, if aContainer is a focus cycle root, then the focus owner is set to aContainer's default Component to focus, and the current focus cycle root is set to aContainer. If aContainer is not a focus cycle root, then no focus traversal operation occurs.
        Parameters:
        aContainer - the Container that is the basis for the focus traversal operation

      • focusNextComponent

        public final void focusNextComponent()
        Focuses the Component after the current focus owner.

      • focusPreviousComponent

        public final void focusPreviousComponent()
        Focuses the Component before the current focus owner.

      • upFocusCycle

        public final void upFocusCycle()
        Moves the focus up one focus traversal cycle from the current focus owner. Typically, the new focus owner is set to the current focus owner's focus cycle root, and the current focus cycle root is set to the new focus owner's focus cycle root. If, however, the current focus owner's focus cycle root is a Window, then typically the focus owner is set to the focus cycle root's default Component to focus, and the current focus cycle root is unchanged.

      • downFocusCycle

        public final void downFocusCycle()
        Moves the focus down one focus traversal cycle from the current focus owner, if and only if the current focus owner is a Container that is a focus cycle root. Typically, the focus owner is set to the current focus owner's default Component to focus, and the current focus cycle root is set to the current focus owner. If the current focus owner is not a Container that is a focus cycle root, then no focus traversal operation occurs.
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Java™ Platform
Standard Ed. 8

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