Module java.desktop
Package java.awt

# Class DefaultKeyboardFocusManager

java.lang.Object
java.awt.KeyboardFocusManager
java.awt.DefaultKeyboardFocusManager

All Implemented Interfaces:
  `KeyEventDispatcher`, `KeyEventPostProcessor`

Direct Known Subclasses:
  `FocusManager`

public class DefaultKeyboardFocusManager extends KeyboardFocusManager
The default KeyboardFocusManager for AWT applications. Focus traversal is done in response to a Component's focus traversal keys, and using a Container's FocusTraversalPolicy.

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:
  - `FocusTraversalPolicy`
  - `Component.setFocusTraversalKeys(int, java.util.Set<? extends java.awt.AWTKeyStroke>)`
  - `Component.getFocusTraversalKeys(int)`

- ## Field Summary

  ### Fields declared in class java.awt.KeyboardFocusManager

  `BACKWARD_TRAVERSAL_KEYS, DOWN_CYCLE_TRAVERSAL_KEYS, FORWARD_TRAVERSAL_KEYS, UP_CYCLE_TRAVERSAL_KEYS`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `DefaultKeyboardFocusManager()`
  Constructs a `DefaultKeyboardFocusManager`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected void`
  `dequeueKeyEvents(long after, Component untilFocused)`
  Releases for normal dispatching to the current focus owner all KeyEvents which were enqueued because of a call to `enqueueKeyEvents` with the same timestamp and Component.
  `protected void`
  `discardKeyEvents(Component comp)`
  Discards all KeyEvents which were enqueued because of one or more calls to `enqueueKeyEvents` with the specified Component, or one of its descendants.
  `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.
  `boolean`
  `dispatchKeyEvent(KeyEvent e)`
  Called by `dispatchEvent` if no other KeyEventDispatcher in the dispatcher chain dispatched the KeyEvent, or if no other KeyEventDispatchers are registered.
  `void`
  `downFocusCycle(Container aContainer)`
  Moves the focus down one focus traversal cycle.
  `protected void`
  `enqueueKeyEvents(long after, Component untilFocused)`
  Delays dispatching of KeyEvents until the specified Component becomes the focus owner.
  `void`
  `focusNextComponent(Component aComponent)`
  Focuses the Component after aComponent, typically based on a FocusTraversalPolicy.
  `void`
  `focusPreviousComponent(Component aComponent)`
  Focuses the Component before aComponent, typically based on a FocusTraversalPolicy.
  `boolean`
  `postProcessKeyEvent(KeyEvent e)`
  This method will be called by `dispatchKeyEvent`.
  `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.
  `void`
  `upFocusCycle(Component aComponent)`
  Moves the focus up one focus traversal cycle.

  ### Methods declared in class java.awt.KeyboardFocusManager

  `addKeyEventDispatcher, addKeyEventPostProcessor, addPropertyChangeListener, addPropertyChangeListener, addVetoableChangeListener, addVetoableChangeListener, clearFocusOwner, clearGlobalFocusOwner, downFocusCycle, firePropertyChange, fireVetoableChange, focusNextComponent, focusPreviousComponent, getActiveWindow, getCurrentFocusCycleRoot, getCurrentKeyboardFocusManager, getDefaultFocusTraversalKeys, getDefaultFocusTraversalPolicy, getFocusedWindow, getFocusOwner, getGlobalActiveWindow, getGlobalCurrentFocusCycleRoot, getGlobalFocusedWindow, getGlobalFocusOwner, getGlobalPermanentFocusOwner, getKeyEventDispatchers, getKeyEventPostProcessors, getPermanentFocusOwner, getPropertyChangeListeners, getPropertyChangeListeners, getVetoableChangeListeners, getVetoableChangeListeners, redispatchEvent, removeKeyEventDispatcher, removeKeyEventPostProcessor, removePropertyChangeListener, removePropertyChangeListener, removeVetoableChangeListener, removeVetoableChangeListener, setCurrentKeyboardFocusManager, setDefaultFocusTraversalKeys, setDefaultFocusTraversalPolicy, setGlobalActiveWindow, setGlobalCurrentFocusCycleRoot, setGlobalFocusedWindow, setGlobalFocusOwner, setGlobalPermanentFocusOwner, upFocusCycle`

  ### Methods declared in class java.lang.Object

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

- ## Constructor Details

  - ### DefaultKeyboardFocusManager

    public DefaultKeyboardFocusManager()
    Constructs a `DefaultKeyboardFocusManager`.

- ## Method Details

  - ### dispatchEvent

    public 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. DefaultKeyboardFocusManagers dispatch all FocusEvents, all WindowEvents related to focus, and all KeyEvents. These events are 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. If this method returns `false`, then the AWT event dispatcher will attempt to dispatch the event itself.
    Specified by:
      `dispatchEvent` in class `KeyboardFocusManager`
    Parameters:
      `e` - the AWTEvent to be dispatched
    Returns:
      `true` if this method dispatched the event; `false` otherwise
    See Also:
      - `KeyboardFocusManager.redispatchEvent(java.awt.Component, java.awt.AWTEvent)`
      - `KeyboardFocusManager.dispatchKeyEvent(java.awt.event.KeyEvent)`

  - ### dispatchKeyEvent

    public boolean dispatchKeyEvent(KeyEvent e)
    Called by `dispatchEvent` if no other KeyEventDispatcher in the dispatcher chain dispatched the KeyEvent, or if no other KeyEventDispatchers are registered. If the event has not been consumed, its target is enabled, and the focus owner is not null, this method dispatches the event to its target. This method will also subsequently dispatch the event to all registered KeyEventPostProcessors. After all this operations are finished, the event is passed to peers for processing.

    In all cases, this method returns `true`, since DefaultKeyboardFocusManager is designed so that neither `dispatchEvent`, nor the AWT event dispatcher, should take further action on the event in any situation.

    Specified by:
      `dispatchKeyEvent` in interface `KeyEventDispatcher`
    Specified by:
      `dispatchKeyEvent` in class `KeyboardFocusManager`
    Parameters:
      `e` - the KeyEvent to be dispatched
    Returns:
      `true`
    See Also:
      - `Component.dispatchEvent(java.awt.AWTEvent)`

  - ### postProcessKeyEvent

    public boolean postProcessKeyEvent(KeyEvent e)
    This method will be called by `dispatchKeyEvent`. It 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`
    Specified by:
      `postProcessKeyEvent` in class `KeyboardFocusManager`
    Parameters:
      `e` - the KeyEvent to post-process
    Returns:
      `true`
    See Also:
      - `dispatchKeyEvent(java.awt.event.KeyEvent)`
      - `MenuShortcut`

  - ### processKeyEvent

    public 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 focus owner.
    Specified by:
      `processKeyEvent` in class `KeyboardFocusManager`
    Parameters:
      `focusedComponent` - the Component that is 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 void enqueueKeyEvents(long after, Component untilFocused)
    Delays dispatching of KeyEvents until the specified Component becomes the focus owner. KeyEvents with timestamps later than the specified timestamp will be enqueued until the specified Component receives a FOCUS_GAINED event, or the AWT cancels the delay request by invoking `dequeueKeyEvents` or `discardKeyEvents`.
    Specified by:
      `enqueueKeyEvents` in class `KeyboardFocusManager`
    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 will receive a FOCUS_GAINED event before any pending KeyEvents
    See Also:
      - `dequeueKeyEvents(long, java.awt.Component)`
      - `discardKeyEvents(java.awt.Component)`

  - ### dequeueKeyEvents

    protected void dequeueKeyEvents(long after, Component untilFocused)
    Releases for normal dispatching to the current focus owner all KeyEvents which were enqueued because of a call to `enqueueKeyEvents` with the same timestamp and Component. 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.
    Specified by:
      `dequeueKeyEvents` in class `KeyboardFocusManager`
    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 void discardKeyEvents(Component comp)
    Discards all KeyEvents which were enqueued because of one or more calls to `enqueueKeyEvents` with the specified Component, or one of its descendants.
    Specified by:
      `discardKeyEvents` in class `KeyboardFocusManager`
    Parameters:
      `comp` - the Component specified in one or more calls to `enqueueKeyEvents`, or a parent of such a Component
    See Also:
      - `enqueueKeyEvents(long, java.awt.Component)`
      - `dequeueKeyEvents(long, java.awt.Component)`

  - ### focusPreviousComponent

    public void focusPreviousComponent(Component aComponent)
    Focuses the Component before aComponent, typically based on a FocusTraversalPolicy.
    Specified by:
      `focusPreviousComponent` in class `KeyboardFocusManager`
    Parameters:
      `aComponent` - the Component that is the basis for the focus traversal operation
    See Also:
      - `FocusTraversalPolicy`
      - `Component.transferFocusBackward()`

  - ### focusNextComponent

    public void focusNextComponent(Component aComponent)
    Focuses the Component after aComponent, typically based on a FocusTraversalPolicy.
    Specified by:
      `focusNextComponent` in class `KeyboardFocusManager`
    Parameters:
      `aComponent` - the Component that is the basis for the focus traversal operation
    See Also:
      - `FocusTraversalPolicy`
      - `Component.transferFocus()`

  - ### upFocusCycle

    public 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 the focus owner is set to the focus cycle root's default Component to focus, and the current focus cycle root is unchanged.
    Specified by:
      `upFocusCycle` in class `KeyboardFocusManager`
    Parameters:
      `aComponent` - the Component that is the basis for the focus traversal operation
    See Also:
      - `Component.transferFocusUpCycle()`

  - ### downFocusCycle

    public void downFocusCycle(Container aContainer)
    Moves the focus down one focus traversal cycle. 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.
    Specified by:
      `downFocusCycle` in class `KeyboardFocusManager`
    Parameters:
      `aContainer` - the Container that is the basis for the focus traversal operation
    See Also:
      - `Container.transferFocusDownCycle()`