java.awt

Class ContainerOrderFocusTraversalPolicy

java.lang.Object

java.awt.FocusTraversalPolicy

java.awt.ContainerOrderFocusTraversalPolicy

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

DefaultFocusTraversalPolicy

public class ContainerOrderFocusTraversalPolicy
extends FocusTraversalPolicy
implements Serializable

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.

By default, ContainerOrderFocusTraversalPolicy implicitly transfers focus down-cycle. That is, during normal forward focus traversal, the Component traversed after a focus cycle root will be the focus-cycle-root's default Component to focus. This behavior can be disabled using the setImplicitDownCycleTraversal method.

By default, methods of this class with return a Component only if it is visible, displayable, enabled, and focusable. Subclasses can modify this behavior by overriding the accept method.

Since:

1.4

Version:

1.3, 01/23/03

Author:

David Mendenhall

See Also:

Container.getComponents(), Serialized Form

Constructor Summary

Constructors

Constructor and Description
ContainerOrderFocusTraversalPolicy()

Method Summary

Methods

Modifier and Type	Method and Description
protected boolean	accept(Component aComponent) Determines whether a Component is an acceptable choice as the new focus owner.
Component	getComponentAfter(Container focusCycleRoot, Component aComponent) Returns the Component that should receive the focus after aComponent.
Component	getComponentBefore(Container focusCycleRoot, Component aComponent) Returns the Component that should receive the focus before aComponent.
Component	getDefaultComponent(Container focusCycleRoot) Returns the default Component to focus.
Component	getFirstComponent(Container focusCycleRoot) Returns the first Component in the traversal cycle.
boolean	getImplicitDownCycleTraversal() Returns whether this ContainerOrderFocusTraversalPolicy transfers focus down-cycle implicitly.
Component	getLastComponent(Container focusCycleRoot) Returns the last Component in the traversal cycle.
void	setImplicitDownCycleTraversal(boolean implicitDownCycleTraversal) Sets whether this ContainerOrderFocusTraversalPolicy transfers focus down-cycle implicitly.

Methods inherited from class java.awt.FocusTraversalPolicy

getInitialComponent

Methods inherited from class java.lang.Object

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

Constructor Detail

ContainerOrderFocusTraversalPolicy

public ContainerOrderFocusTraversalPolicy()

Method Detail

getComponentAfter

public Component getComponentAfter(Container focusCycleRoot,
                          Component aComponent)

Returns the Component that should receive the focus after aComponent. focusCycleRoot must be a focus cycle root of aComponent.

By default, ContainerOrderFocusTraversalPolicy implicitly transfers focus down-cycle. That is, during normal forward focus traversal, the Component traversed after a focus cycle root will be the focus-cycle- root's default Component to focus. This behavior can be disabled using the setImplicitDownCycleTraversal method.

Specified by:

getComponentAfter in class FocusTraversalPolicy

Parameters:

focusCycleRoot - a focus cycle root of aComponent

aComponent - a (possibly indirect) child of focusCycleRoot, or focusCycleRoot itself

Returns:

the Component that should receive the focus after aComponent, or null if no suitable Component can be found

Throws:

IllegalArgumentException - if focusCycleRoot is not a focus cycle root of aComponent, or if either focusCycleRoot or aComponent is null

getComponentBefore

public Component getComponentBefore(Container focusCycleRoot,
                           Component aComponent)

Returns the Component that should receive the focus before aComponent. focusCycleRoot must be a focus cycle root of aComponent.

Specified by:

getComponentBefore in class FocusTraversalPolicy

Parameters:

focusCycleRoot - a focus cycle root of aComponent

aComponent - a (possibly indirect) child of focusCycleRoot, or focusCycleRoot itself

Returns:

the Component that should receive the focus before aComponent, or null if no suitable Component can be found

Throws:

IllegalArgumentException - if focusCycleRoot is not a focus cycle root of aComponent, or if either focusCycleRoot or aComponent is null

getFirstComponent

public Component getFirstComponent(Container focusCycleRoot)

Returns the first Component in the traversal cycle. This method is used to determine the next Component to focus when traversal wraps in the forward direction.

Specified by:

getFirstComponent in class FocusTraversalPolicy

Parameters:

focusCycleRoot - the focus cycle root whose first Component is to be returned

Returns:

the first Component in the traversal cycle when focusCycleRoot is the focus cycle root, or null if no suitable Component can be found

Throws:

IllegalArgumentException - if focusCycleRoot is null

getLastComponent

public Component getLastComponent(Container focusCycleRoot)

Returns the last Component in the traversal cycle. This method is used to determine the next Component to focus when traversal wraps in the reverse direction.

Specified by:

getLastComponent in class FocusTraversalPolicy

Parameters:

focusCycleRoot - the focus cycle root whose last Component is to be returned

Returns:

the last Component in the traversal cycle when focusCycleRoot is the focus cycle root, or null if no suitable Component can be found

Throws:

IllegalArgumentException - if focusCycleRoot is null

getDefaultComponent

public Component getDefaultComponent(Container focusCycleRoot)

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 focusCycleRoot. The default implementation of this method returns the same Component as getFirstComponent.

Specified by:

getDefaultComponent in class FocusTraversalPolicy

Parameters:

focusCycleRoot - the focus cycle root whose default Component is to be returned

Returns:

the default Component in the traversal cycle when focusCycleRoot is the focus cycle root, or null if no suitable Component can be found

Throws:

IllegalArgumentException - if focusCycleRoot is null

See Also:

getFirstComponent(java.awt.Container)

setImplicitDownCycleTraversal

public void setImplicitDownCycleTraversal(boolean implicitDownCycleTraversal)

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:

getImplicitDownCycleTraversal(), getFirstComponent(java.awt.Container)

getImplicitDownCycleTraversal

public boolean getImplicitDownCycleTraversal()

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:

setImplicitDownCycleTraversal(boolean), getFirstComponent(java.awt.Container)

accept

protected boolean accept(Component aComponent)

Determines whether a Component is an acceptable choice as the new focus owner. By default, this method will accept a Component if and only if it is visible, displayable, enabled, and focusable.

Parameters:

aComponent - the Component whose fitness as a focus owner is to be tested

Returns:

true if aComponent is visible, displayable, enabled, and focusable; false otherwise