javax.swing
Class SortingFocusTraversalPolicy

java.lang.Object
  java.awt.FocusTraversalPolicy
      javax.swing.InternalFrameFocusTraversalPolicy
          javax.swing.SortingFocusTraversalPolicy

Direct Known Subclasses:

LayoutFocusTraversalPolicy

public class SortingFocusTraversalPolicy

extends InternalFrameFocusTraversalPolicy

A FocusTraversalPolicy that determines traversal order by sorting the Components of a focus traversal cycle based on a given Comparator. Portions of the Component hierarchy that are not visible and displayable will not be included.

By default, SortingFocusTraversalPolicy implicitly transfers focus down- cycle. That is, during normal 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

Author:

David Mendenhall

See Also:

Comparator

Field Summary

private List	cachedCycle
private Container	cachedRoot Used by getComponentAfter and getComponentBefore for efficiency.
private Comparator	comparator
private static SwingContainerOrderFocusTraversalPolicy	fitnessTestPolicy
private boolean	implicitDownCycleTraversal

Constructor Summary

protected	SortingFocusTraversalPolicy() Constructs a SortingFocusTraversalPolicy without a Comparator.
	SortingFocusTraversalPolicy(Comparator comparator) Constructs a SortingFocusTraversalPolicy with the specified Comparator.

Method Summary

protected boolean	accept(Component aComponent) Determines whether a Component is an acceptable choice as the new focus owner.
private void	enumerateAndSortCycle(Container focusCycleRoot, List cycle, Map defaults)
private void	enumerateCycle(Container container, List cycle)
protected Comparator	getComparator() Returns the Comparator which will be used to sort the Components in a focus traversal cycle.
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 SortingFocusTraversalPolicy transfers focus down- cycle implicitly.
Component	getLastComponent(Container focusCycleRoot) Returns the last Component in the traversal cycle.
protected void	setComparator(Comparator comparator) Sets the Comparator which will be used to sort the Components in a focus traversal cycle.
void	setImplicitDownCycleTraversal(boolean implicitDownCycleTraversal) Sets whether this SortingFocusTraversalPolicy transfers focus down-cycle implicitly.

Methods inherited from class javax.swing.InternalFrameFocusTraversalPolicy

getInitialComponent

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

Field Detail

comparator

private Comparator comparator

implicitDownCycleTraversal

private boolean implicitDownCycleTraversal

cachedRoot

private Container cachedRoot

Used by getComponentAfter and getComponentBefore for efficiency. In order to maintain compliance with the specification of FocusTraversalPolicy, if traversal wraps, we should invoke getFirstComponent or getLastComponent. These methods may be overriden in subclasses to behave in a non-generic way. However, in the generic case, these methods will simply return the first or last Components of the sorted list, respectively. Since getComponentAfter and getComponentBefore have already built the sorted list before determining that they need to invoke getFirstComponent or getLastComponent, the sorted list should be reused if possible.

cachedCycle

private List cachedCycle

fitnessTestPolicy

private static final SwingContainerOrderFocusTraversalPolicy fitnessTestPolicy

Constructor Detail

SortingFocusTraversalPolicy

protected SortingFocusTraversalPolicy()

Constructs a SortingFocusTraversalPolicy without a Comparator. Subclasses must set the Comparator using setComparator before installing this FocusTraversalPolicy on a focus cycle root or KeyboardFocusManager.

SortingFocusTraversalPolicy

public SortingFocusTraversalPolicy(Comparator comparator)

Constructs a SortingFocusTraversalPolicy with the specified Comparator.

Method Detail

enumerateAndSortCycle

private void enumerateAndSortCycle(Container focusCycleRoot,
                                   List cycle,
                                   Map defaults)

enumerateCycle

private void enumerateCycle(Container container,
                            List cycle)

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, SortingFocusTraversalPolicy implicitly transfers focus down- cycle. That is, during normal 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.

By default, SortingFocusTraversalPolicy implicitly transfers focus down- cycle. That is, during normal 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:

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 SortingFocusTraversalPolicy transfers focus down-cycle implicitly. If true, during normal 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 SortingFocusTraversalPolicy transfers focus down-cycle implicitly

See Also:

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

getImplicitDownCycleTraversal

public boolean getImplicitDownCycleTraversal()

Returns whether this SortingFocusTraversalPolicy transfers focus down- cycle implicitly. If true, during normal 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 SortingFocusTraversalPolicy transfers focus down- cycle implicitly

See Also:

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

setComparator

protected void setComparator(Comparator comparator)

Sets the Comparator which will be used to sort the Components in a focus traversal cycle.

Parameters:

comparator - the Comparator which will be used for sorting

getComparator

protected Comparator getComparator()

Returns the Comparator which will be used to sort the Components in a focus traversal cycle.

Returns:

the Comparator which will be used for sorting

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