+ * 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 Logger log = Logger.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 cachedCycle;
+
+ // Delegate our fitness test to ContainerOrder so that we only have to
+ // code the algorithm once.
+ private static final SwingContainerOrderFocusTraversalPolicy
+ fitnessTestPolicy = new SwingContainerOrderFocusTraversalPolicy();
+
+ final private int FORWARD_TRAVERSAL = 0;
+ final private int BACKWARD_TRAVERSAL = 1;
+
+ /**
+ * Constructs a SortingFocusTraversalPolicy without a Comparator.
+ * Subclasses must set the Comparator using
+ * 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(Level.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(Level.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(Level.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(Level.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(Level.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);
+ }
+}