DefaultFocusTraversalPolicy JDK 1.6)

Description

public class DefaultFocusTraversalPolicy

A FocusTraversalPolicy that determines traversal order based on the order of child Components in a Container.

A FocusTraversalPolicy that determines traversal order based on the order of child Components in a Container. From a particular focus cycle root, the policy makes a pre-order traversal of the Component hierarchy, and traverses a Container's children according to the ordering of the array returned by Container.getComponents(). Portions of the hierarchy that are not visible and displayable will not be searched.

If client code has explicitly set the focusability of a Component by either overriding Component.isFocusTraversable() or Component.isFocusable(), or by calling Component.setFocusable(), then a DefaultFocusTraversalPolicy behaves exactly like a ContainerOrderFocusTraversalPolicy. If, however, the Component is relying on default focusability, then a DefaultFocusTraversalPolicy will reject all Components with non-focusable peers. This is the default FocusTraversalPolicy for all AWT Containers.

The focusability of a peer is implementation-dependent. Sun recommends that all implementations for a particular native platform construct peers with the same focusability. The recommendations for Windows and Unix are that Canvases, Labels, Panels, Scrollbars, ScrollPanes, Windows, and lightweight Components have non-focusable peers, and all other Components have focusable peers. These recommendations are used in the Sun AWT implementations. Note that the focusability of a Component's peer is different from, and does not impact, the focusability of the Component itself.

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

See also: Container.getComponents() Component.isFocusable() Component.setFocusable(boolean)

Methods

Hide/Show inherited methods

protected boolean accept (Component aComponent) [Overrides ContainerOrderFocusTraversalPolicy]

Determines whether a Component is an acceptable choice as the new focus owner.

Determines whether a Component is an acceptable choice as the new
focus owner. The Component must be visible, displayable, and enabled
to be accepted. If client code has explicitly set the focusability
of the Component by either overriding
Component.isFocusTraversable() or
Component.isFocusable(), or by calling
Component.setFocusable(), then the Component will be
accepted if and only if it is focusable. If, however, the Component is
relying on default focusability, then all Canvases, Labels, Panels,
Scrollbars, ScrollPanes, Windows, and lightweight Components will be
rejected.
Returns: true if aComponent meets the above requirements; false otherwise
Parameters:
- aComponent - the Component whose fitness as a focus owner is to be tested

public Component getComponentAfter (Container aContainer, Component aComponent) [Inherited From ContainerOrderFocusTraversalPolicy] [Specified in FocusTraversalPolicy]

Returns the Component that should receive the focus after aComponent.

public Component getComponentBefore (Container aContainer, Component aComponent) [Inherited From ContainerOrderFocusTraversalPolicy] [Specified in FocusTraversalPolicy]

Returns the Component that should receive the focus before aComponent.

public Component getDefaultComponent (Container aContainer) [Inherited From ContainerOrderFocusTraversalPolicy] [Specified in FocusTraversalPolicy]

Returns the default Component to focus.

Returns the default Component to focus. This Component will be the first
to receive focus when traversing down into a new focus traversal cycle
rooted at aContainer. The default implementation of this method
returns the same Component as getFirstComponent.
Returns: the default Component in the traversal cycle of aContainer, or null if no suitable Component can be found
Parameters:
- aContainer - the focus cycle root or focus traversal policy provider whose default Component is to be returned
Throws:
- IllegalArgumentException - if aContainer is null
See Also: ContainerOrderFocusTraversalPolicy.getFirstComponent(java.awt.Container),

public Component getFirstComponent (Container aContainer) [Inherited From ContainerOrderFocusTraversalPolicy] [Specified in FocusTraversalPolicy]

Returns the first Component in the traversal cycle.

public boolean getImplicitDownCycleTraversal () [Inherited From ContainerOrderFocusTraversalPolicy]

Returns whether this ContainerOrderFocusTraversalPolicy transfers focus down-cycle implicitly.

Returns whether this ContainerOrderFocusTraversalPolicy transfers focus
down-cycle implicitly. If true, during normal forward focus
traversal, the Component traversed after a focus cycle root will be the
focus-cycle-root's default Component to focus. If false,
the next Component in the focus traversal cycle rooted at the specified
focus cycle root will be traversed instead.
Returns: whether this ContainerOrderFocusTraversalPolicy transfers focus down-cycle implicitly
See Also: ContainerOrderFocusTraversalPolicy.setImplicitDownCycleTraversal(boolean), ContainerOrderFocusTraversalPolicy.getFirstComponent(java.awt.Container),

public Component getInitialComponent (Window window) [Inherited From FocusTraversalPolicy]

Returns the Component that should receive the focus when a Window is made visible for the first time.

Returns the Component that should receive the focus when a Window is
made visible for the first time. Once the Window has been made visible
by a call to show() or setVisible(true), the
initial Component will not be used again. Instead, if the Window loses
and subsequently regains focus, or is made invisible or undisplayable
and subsequently made visible and displayable, the Window's most
recently focused Component will become the focus owner. The default
implementation of this method returns the default Component.
Returns: the Component that should receive the focus when window is made visible for the first time, or null if no suitable Component can be found
Parameters:
- window - the Window whose initial Component is to be returned
Throws:
- IllegalArgumentException - if window is null
See Also: FocusTraversalPolicy.getDefaultComponent(java.awt.Container), Window.getMostRecentFocusOwner(),

public Component getLastComponent (Container aContainer) [Inherited From ContainerOrderFocusTraversalPolicy] [Specified in FocusTraversalPolicy]

Returns the last Component in the traversal cycle.

public void setImplicitDownCycleTraversal (boolean implicitDownCycleTraversal) [Inherited From ContainerOrderFocusTraversalPolicy]

Sets whether this ContainerOrderFocusTraversalPolicy transfers focus down-cycle implicitly.

Sets whether this ContainerOrderFocusTraversalPolicy transfers focus
down-cycle implicitly. If true, during normal forward focus
traversal, the Component traversed after a focus cycle root will be the
focus-cycle-root's default Component to focus. If false,
the next Component in the focus traversal cycle rooted at the specified
focus cycle root will be traversed instead. The default value for this
property is true.
Parameters:
- implicitDownCycleTraversal - whether this ContainerOrderFocusTraversalPolicy transfers focus down-cycle implicitly
See Also: ContainerOrderFocusTraversalPolicy.getImplicitDownCycleTraversal(), ContainerOrderFocusTraversalPolicy.getFirstComponent(java.awt.Container),