* 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.
*
* This policy takes into account focus traversal
* policy providers. When searching for first/last/next/previous Component,
* if a focus traversal policy provider is encountered, its focus traversal
* policy is used to perform the search operation.
*
* @author David Mendenhall
*
* @see java.util.Comparator
* @since 1.4
*/
public class SortingFocusTraversalPolicy
extends InternalFrameFocusTraversalPolicy
{
private Comparator comparator;
private boolean implicitDownCycleTraversal = true;
private PlatformLogger log = PlatformLogger.getLogger("javax.swing.SortingFocusTraversalPolicy");
/**
* 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.
*/
transient private Container cachedRoot;
transient private List
* 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
*
* If aContainer is focus
* traversal policy provider, the focus is always transferred down-cycle.
*
* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider
* @param aComponent a (possibly indirect) child of aContainer, or
* aContainer itself
* @return the Component that should receive the focus after aComponent, or
* null if no suitable Component can be found
* @throws IllegalArgumentException if aContainer is not a focus cycle
* root of aComponent or a focus traversal policy provider, or if either aContainer or
* aComponent is null
*/
public Component getComponentAfter(Container aContainer, Component aComponent) {
if (log.isLoggable(PlatformLogger.FINE)) {
log.fine("### Searching in " + aContainer + " for component after " + aComponent);
}
if (aContainer == null || aComponent == null) {
throw new IllegalArgumentException("aContainer and aComponent cannot be null");
}
if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");
} else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
}
// Before all the ckecks below we first see if it's an FTP provider or a focus cycle root.
// If it's the case just go down cycle (if it's set to "implicit").
Component comp = getComponentDownCycle(aComponent, FORWARD_TRAVERSAL);
if (comp != null) {
return comp;
}
// See if the component is inside of policy provider.
Container provider = getTopmostProvider(aContainer, aComponent);
if (provider != null) {
if (log.isLoggable(PlatformLogger.FINE)) {
log.fine("### Asking FTP " + provider + " for component after " + aComponent);
}
// FTP knows how to find component after the given. We don't.
FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
Component afterComp = policy.getComponentAfter(provider, aComponent);
// Null result means that we overstepped the limit of the FTP's cycle.
// In that case we must quit the cycle, otherwise return the component found.
if (afterComp != null) {
if (log.isLoggable(PlatformLogger.FINE)) log.fine("### FTP returned " + afterComp);
return afterComp;
}
aComponent = provider;
}
List
* 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
*
* If aContainer is focus
* traversal policy provider, the focus is always transferred down-cycle.
*
* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider
* @param aComponent a (possibly indirect) child of aContainer, or
* aContainer itself
* @return the Component that should receive the focus before aComponent,
* or null if no suitable Component can be found
* @throws IllegalArgumentException if aContainer is not a focus cycle
* root of aComponent or a focus traversal policy provider, or if either aContainer or
* aComponent is null
*/
public Component getComponentBefore(Container aContainer, Component aComponent) {
if (aContainer == null || aComponent == null) {
throw new IllegalArgumentException("aContainer and aComponent cannot be null");
}
if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");
} else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
}
// See if the component is inside of policy provider.
Container provider = getTopmostProvider(aContainer, aComponent);
if (provider != null) {
if (log.isLoggable(PlatformLogger.FINE)) {
log.fine("### Asking FTP " + provider + " for component after " + aComponent);
}
// FTP knows how to find component after the given. We don't.
FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
Component beforeComp = policy.getComponentBefore(provider, aComponent);
// Null result means that we overstepped the limit of the FTP's cycle.
// In that case we must quit the cycle, otherwise return the component found.
if (beforeComp != null) {
if (log.isLoggable(PlatformLogger.FINE)) log.fine("### FTP returned " + beforeComp);
return beforeComp;
}
aComponent = provider;
// If the provider is traversable it's returned.
if (accept(aComponent)) {
return aComponent;
}
}
ListsetComparator
* before installing this FocusTraversalPolicy on a focus cycle root or
* KeyboardFocusManager.
*/
protected SortingFocusTraversalPolicy() {
}
/**
* Constructs a SortingFocusTraversalPolicy with the specified Comparator.
*/
public SortingFocusTraversalPolicy(Comparator comparator) {
this.comparator = comparator;
}
private ListsetImplicitDownCycleTraversal method.
* setImplicitDownCycleTraversal method.
* getFirstComponent.
*
* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose
* default Component is to be returned
* @return the default Component in the traversal cycle of aContainer,
* or null if no suitable Component can be found
* @see #getFirstComponent
* @throws IllegalArgumentException if aContainer is null
*/
public Component getDefaultComponent(Container aContainer) {
return getFirstComponent(aContainer);
}
/**
* 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.
*
* @param implicitDownCycleTraversal whether this
* SortingFocusTraversalPolicy transfers focus down-cycle implicitly
* @see #getImplicitDownCycleTraversal
* @see #getFirstComponent
*/
public void setImplicitDownCycleTraversal(boolean implicitDownCycleTraversal) {
this.implicitDownCycleTraversal = implicitDownCycleTraversal;
}
/**
* 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.
*
* @return whether this SortingFocusTraversalPolicy transfers focus down-
* cycle implicitly
* @see #setImplicitDownCycleTraversal
* @see #getFirstComponent
*/
public boolean getImplicitDownCycleTraversal() {
return implicitDownCycleTraversal;
}
/**
* Sets the Comparator which will be used to sort the Components in a
* focus traversal cycle.
*
* @param comparator the Comparator which will be used for sorting
*/
protected void setComparator(Comparator comparator) {
this.comparator = comparator;
}
/**
* Returns the Comparator which will be used to sort the Components in a
* focus traversal cycle.
*
* @return the Comparator which will be used for sorting
*/
protected Comparator getComparator() {
return comparator;
}
/**
* 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.
*
* @param aComponent the Component whose fitness as a focus owner is to
* be tested
* @return true if aComponent is visible, displayable,
* enabled, and focusable; false otherwise
*/
protected boolean accept(Component aComponent) {
return fitnessTestPolicy.accept(aComponent);
}
}
// Create our own subclass and change accept to public so that we can call
// accept.
class SwingContainerOrderFocusTraversalPolicy
extends java.awt.ContainerOrderFocusTraversalPolicy
{
public boolean accept(Component aComponent) {
return super.accept(aComponent);
}
}