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package javax.swing;

import java.awt.Component;
import java.awt.Container;
import java.util.*;
import java.awt.FocusTraversalPolicy;
import sun.util.logging.PlatformLogger;
import sun.security.action.GetPropertyAction;
import java.security.AccessController;


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.


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 Also:
Since:1.4
/**
 * 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.
 * <p>
 * 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
 * <code>setImplicitDownCycleTraversal</code> method.
 * <p>
 * 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 <code>accept</code> method.
 * <p>
 * This policy takes into account <a
 * href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus traversal
 * policy providers</a>.  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<? super Component> 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.

/**
     * 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.
     */
    private transient Container cachedRoot;
    private transient List<Component> cachedCycle;

    // Delegate our fitness test to ContainerOrder so that we only have to
    // code the algorithm once.
    private static final SwingContainerOrderFocusTraversalPolicy
        fitnessTestPolicy = new SwingContainerOrderFocusTraversalPolicy();

    private final int FORWARD_TRAVERSAL = 0;
    private final int BACKWARD_TRAVERSAL = 1;

    /*
     * When true (by default), the legacy merge-sort algo is used to sort an FTP cycle.
     * When false, the default (tim-sort) algo is used, which may lead to an exception.
     * See: JDK-8048887
     */
    private static final boolean legacySortingFTPEnabled;

    static {
        legacySortingFTPEnabled = "true".equals(AccessController.doPrivileged(
            new GetPropertyAction("swing.legacySortingFTPEnabled", "true")));
    }

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

/**
     * Constructs a SortingFocusTraversalPolicy without a Comparator.
     * Subclasses must set the Comparator using <code>setComparator</code>
     * before installing this FocusTraversalPolicy on a focus cycle root or
     * KeyboardFocusManager.
     */
    protected SortingFocusTraversalPolicy() {
    }

    
Constructs a SortingFocusTraversalPolicy with the specified Comparator.

Params:
  • comparator – the Comparator to sort by
/**
     * Constructs a SortingFocusTraversalPolicy with the specified Comparator.
     *
     * @param comparator the {@code Comparator} to sort by
     */
    public SortingFocusTraversalPolicy(Comparator<? super Component> comparator) {
        this.comparator = comparator;
    }

    private List<Component> getFocusTraversalCycle(Container aContainer) {
        List<Component> cycle = new ArrayList<Component>();
        enumerateAndSortCycle(aContainer, cycle);
        return cycle;
    }
    private int getComponentIndex(List<Component> cycle, Component aComponent) {
        int index;
        try {
            index = Collections.binarySearch(cycle, aComponent, comparator);
        } catch (ClassCastException e) {
            if (log.isLoggable(PlatformLogger.Level.FINE)) {
                log.fine("### During the binary search for " + aComponent + " the exception occurred: ", e);
            }
            return -1;
        }
        if (index < 0) {
            // Fix for 5070991.
            // A workaround for a transitivity problem caused by ROW_TOLERANCE,
            // because of that the component may be missed in the binary search.
            // Try to search it again directly.
            index = cycle.indexOf(aComponent);
        }
        return index;
    }

    private void enumerateAndSortCycle(Container focusCycleRoot, List<Component> cycle) {
        if (focusCycleRoot.isShowing()) {
            enumerateCycle(focusCycleRoot, cycle);
            if (legacySortingFTPEnabled) {
                legacySort(cycle, comparator);
            } else {
                cycle.sort(comparator);
            }
        }
    }

    private void legacySort(List<Component> l,
                                              Comparator<? super Component> c) {
        if (c != null && l.size() > 1) {
            Component[] a = l.toArray(new Component[l.size()]);
            mergeSort(a.clone(), a, 0, a.length, 0, c);
            ListIterator<Component> i = l.listIterator();
            for (Component e : a) {
                i.next();
                i.set(e);
            }
        }
    }

    @SuppressWarnings("deprecation")
    private void enumerateCycle(Container container, List<Component> cycle) {
        if (!(container.isVisible() && container.isDisplayable())) {
            return;
        }

        cycle.add(container);

        Component[] components = container.getComponents();
        for (Component comp : components) {
            if (comp instanceof Container) {
                Container cont = (Container)comp;

                if (!cont.isFocusCycleRoot() &&
                    !cont.isFocusTraversalPolicyProvider() &&
                    !((cont instanceof JComponent) && ((JComponent)cont).isManagingFocus()))
                {
                    enumerateCycle(cont, cycle);
                    continue;
                }
            }
            cycle.add(comp);
        }
    }

    Container getTopmostProvider(Container focusCycleRoot, Component aComponent) {
        Container aCont = aComponent.getParent();
        Container ftp = null;
        while (aCont  != focusCycleRoot && aCont != null) {
            if (aCont.isFocusTraversalPolicyProvider()) {
                ftp = aCont;
            }
            aCont = aCont.getParent();
        }
        if (aCont == null) {
            return null;
        }
        return ftp;
    }

    /*
     * Checks if a new focus cycle takes place and returns a Component to traverse focus to.
     * @param comp a possible focus cycle root or policy provider
     * @param traversalDirection the direction of the traversal
     * @return a Component to traverse focus to if {@code comp} is a root or provider
     *         and implicit down-cycle is set, otherwise {@code null}
     */
    private Component getComponentDownCycle(Component comp, int traversalDirection) {
        Component retComp = null;

        if (comp instanceof Container) {
            Container cont = (Container)comp;

            if (cont.isFocusCycleRoot()) {
                if (getImplicitDownCycleTraversal()) {
                    retComp = cont.getFocusTraversalPolicy().getDefaultComponent(cont);

                    if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {
                        log.fine("### Transfered focus down-cycle to " + retComp +
                                 " in the focus cycle root " + cont);
                    }
                } else {
                    return null;
                }
            } else if (cont.isFocusTraversalPolicyProvider()) {
                retComp = (traversalDirection == FORWARD_TRAVERSAL ?
                           cont.getFocusTraversalPolicy().getDefaultComponent(cont) :
                           cont.getFocusTraversalPolicy().getLastComponent(cont));

                if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {
                    log.fine("### Transfered focus to " + retComp + " in the FTP provider " + cont);
                }
            }
        }
        return retComp;
    }

    
Returns the Component that should receive the focus after aComponent.
aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.


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.


If aContainer is focus
traversal policy provider, the focus is always transferred down-cycle.

Params:
  • aContainer – a focus cycle root of aComponent or a focus traversal policy provider
  • aComponent – a (possibly indirect) child of aContainer, or
       aContainer itself
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
Returns:the Component that should receive the focus after aComponent, or
        null if no suitable Component can be found
/**
     * Returns the Component that should receive the focus after aComponent.
     * aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.
     * <p>
     * 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
     * <code>setImplicitDownCycleTraversal</code> method.
     * <p>
     * If aContainer is <a href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus
     * traversal policy provider</a>, 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.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(PlatformLogger.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(PlatformLogger.Level.FINE)) {
                    log.fine("### FTP returned " + afterComp);
                }
                return afterComp;
            }
            aComponent = provider;
        }

        List<Component> cycle = getFocusTraversalCycle(aContainer);

        if (log.isLoggable(PlatformLogger.Level.FINE)) {
            log.fine("### Cycle is " + cycle + ", component is " + aComponent);
        }

        int index = getComponentIndex(cycle, aComponent);

        if (index < 0) {
            if (log.isLoggable(PlatformLogger.Level.FINE)) {
                log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
            }
            return getFirstComponent(aContainer);
        }

        for (index++; index < cycle.size(); index++) {
            comp = cycle.get(index);
            if (accept(comp)) {
                return comp;
            } else if ((comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null) {
                return comp;
            }
        }

        if (aContainer.isFocusCycleRoot()) {
            this.cachedRoot = aContainer;
            this.cachedCycle = cycle;

            comp = getFirstComponent(aContainer);

            this.cachedRoot = null;
            this.cachedCycle = null;

            return comp;
        }
        return null;
    }

    
Returns the Component that should receive the focus before aComponent.
aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.


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.


If aContainer is focus
traversal policy provider, the focus is always transferred down-cycle.

Params:
  • aContainer – a focus cycle root of aComponent or a focus traversal policy provider
  • aComponent – a (possibly indirect) child of aContainer, or
       aContainer itself
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
Returns:the Component that should receive the focus before aComponent,
        or null if no suitable Component can be found
/**
     * Returns the Component that should receive the focus before aComponent.
     * aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.
     * <p>
     * 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
     * <code>setImplicitDownCycleTraversal</code> method.
     * <p>
     * If aContainer is <a href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus
     * traversal policy provider</a>, 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.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(PlatformLogger.Level.FINE)) {
                    log.fine("### FTP returned " + beforeComp);
                }
                return beforeComp;
            }
            aComponent = provider;

            // If the provider is traversable it's returned.
            if (accept(aComponent)) {
                return aComponent;
            }
        }

        List<Component> cycle = getFocusTraversalCycle(aContainer);

        if (log.isLoggable(PlatformLogger.Level.FINE)) {
            log.fine("### Cycle is " + cycle + ", component is " + aComponent);
        }

        int index = getComponentIndex(cycle, aComponent);

        if (index < 0) {
            if (log.isLoggable(PlatformLogger.Level.FINE)) {
                log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
            }
            return getLastComponent(aContainer);
        }

        Component comp;
        Component tryComp;

        for (index--; index>=0; index--) {
            comp = cycle.get(index);
            if (comp != aContainer && (tryComp = getComponentDownCycle(comp, BACKWARD_TRAVERSAL)) != null) {
                return tryComp;
            } else if (accept(comp)) {
                return comp;
            }
        }

        if (aContainer.isFocusCycleRoot()) {
            this.cachedRoot = aContainer;
            this.cachedCycle = cycle;

            comp = getLastComponent(aContainer);

            this.cachedRoot = null;
            this.cachedCycle = null;

            return comp;
        }
        return null;
    }

    
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.

Params:
  • aContainer – a focus cycle root of aComponent or a focus traversal policy provider whose
       first Component is to be returned
Throws:
Returns:the first Component in the traversal cycle of aContainer,
        or null if no suitable Component can be found
/**
     * 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.
     *
     * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose
     *        first Component is to be returned
     * @return the first Component in the traversal cycle of aContainer,
     *         or null if no suitable Component can be found
     * @throws IllegalArgumentException if aContainer is null
     */
    public Component getFirstComponent(Container aContainer) {
        List<Component> cycle;

        if (log.isLoggable(PlatformLogger.Level.FINE)) {
            log.fine("### Getting first component in " + aContainer);
        }
        if (aContainer == null) {
            throw new IllegalArgumentException("aContainer cannot be null");
        }

        if (this.cachedRoot == aContainer) {
            cycle = this.cachedCycle;
        } else {
            cycle = getFocusTraversalCycle(aContainer);
        }

        if (cycle.size() == 0) {
            if (log.isLoggable(PlatformLogger.Level.FINE)) {
                log.fine("### Cycle is empty");
            }
            return null;
        }
        if (log.isLoggable(PlatformLogger.Level.FINE)) {
            log.fine("### Cycle is " + cycle);
        }

        for (Component comp : cycle) {
            if (accept(comp)) {
                return comp;
            } else if (comp != aContainer &&
                       (comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null)
            {
                return comp;
            }
        }
        return null;
    }

    
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.

Params:
  • aContainer – a focus cycle root of aComponent or a focus traversal policy provider whose
       last Component is to be returned
Throws:
Returns:the last Component in the traversal cycle of aContainer,
        or null if no suitable Component can be found
/**
     * 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.
     *
     * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose
     *        last Component is to be returned
     * @return the last Component in the traversal cycle of aContainer,
     *         or null if no suitable Component can be found
     * @throws IllegalArgumentException if aContainer is null
     */
    public Component getLastComponent(Container aContainer) {
        List<Component> cycle;
        if (log.isLoggable(PlatformLogger.Level.FINE)) {
            log.fine("### Getting last component in " + aContainer);
        }

        if (aContainer == null) {
            throw new IllegalArgumentException("aContainer cannot be null");
        }

        if (this.cachedRoot == aContainer) {
            cycle = this.cachedCycle;
        } else {
            cycle = getFocusTraversalCycle(aContainer);
        }

        if (cycle.size() == 0) {
            if (log.isLoggable(PlatformLogger.Level.FINE)) {
                log.fine("### Cycle is empty");
            }
            return null;
        }
        if (log.isLoggable(PlatformLogger.Level.FINE)) {
            log.fine("### Cycle is " + cycle);
        }

        for (int i= cycle.size() - 1; i >= 0; i--) {
            Component comp = cycle.get(i);
            if (accept(comp)) {
                return comp;
            } else if (comp instanceof Container && comp != aContainer) {
                Container cont = (Container)comp;
                if (cont.isFocusTraversalPolicyProvider()) {
                    Component retComp = cont.getFocusTraversalPolicy().getLastComponent(cont);
                    if (retComp != null) {
                        return retComp;
                    }
                }
            }
        }
        return null;
    }

    
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.

Params:
  • aContainer – a focus cycle root of aComponent or a focus traversal policy provider whose
       default Component is to be returned
Throws:
See Also:
Returns:the default Component in the traversal cycle of aContainer,
        or null if no suitable Component can be found
/**
     * 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 <code>getFirstComponent</code>.
     *
     * @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.

Params:
  • implicitDownCycleTraversal – whether this
       SortingFocusTraversalPolicy transfers focus down-cycle implicitly
See Also:
/**
     * Sets whether this SortingFocusTraversalPolicy transfers focus down-cycle
     * implicitly. If <code>true</code>, during normal focus traversal,
     * the Component traversed after a focus cycle root will be the focus-
     * cycle-root's default Component to focus. If <code>false</code>, 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 <code>true</code>.
     *
     * @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.

See Also:
Returns:whether this SortingFocusTraversalPolicy transfers focus down-
        cycle implicitly
/**
     * Returns whether this SortingFocusTraversalPolicy transfers focus down-
     * cycle implicitly. If <code>true</code>, during normal focus
     * traversal, the Component traversed after a focus cycle root will be the
     * focus-cycle-root's default Component to focus. If <code>false</code>,
     * 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.

Params:
  • comparator – the Comparator which will be used for sorting
/**
     * 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<? super Component> comparator) {
        this.comparator = comparator;
    }

    
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
/**
     * 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<? super Component> 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.

Params:
  • 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
/**
     * 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 <code>true</code> if aComponent is visible, displayable,
     *         enabled, and focusable; <code>false</code> otherwise
     */
    protected boolean accept(Component aComponent) {
        return fitnessTestPolicy.accept(aComponent);
    }

    // merge sort implementation copied from java.utils.Arrays
    private <T> void mergeSort(T[] src, T[] dest,
                               int low, int high, int off,
                               Comparator<? super T> c) {
        int length = high - low;

        // Insertion sort on smallest arrays
        if (length < 7) {
            for (int i=low; i<high; i++)
                for (int j=i; j>low && c.compare(dest[j-1], dest[j])>0; j--) {
                    T t = dest[j];
                    dest[j] = dest[j-1];
                    dest[j-1] = t;
                }
            return;
        }

        // Recursively sort halves of dest into src
        int destLow  = low;
        int destHigh = high;
        low  += off;
        high += off;
        int mid = (low + high) >>> 1;
        mergeSort(dest, src, low, mid, -off, c);
        mergeSort(dest, src, mid, high, -off, c);

        // If list is already sorted, just copy from src to dest.  This is an
        // optimization that results in faster sorts for nearly ordered lists.
        if (c.compare(src[mid-1], src[mid]) <= 0) {
            System.arraycopy(src, low, dest, destLow, length);
            return;
        }

        // Merge sorted halves (now in src) into dest
        for(int i = destLow, p = low, q = mid; i < destHigh; i++) {
            if (q >= high || p < mid && c.compare(src[p], src[q]) <= 0)
                dest[i] = src[p++];
            else
                dest[i] = src[q++];
        }
    }
}

// Create our own subclass and change accept to public so that we can call
// accept.
@SuppressWarnings("serial") // JDK-implementation class
class SwingContainerOrderFocusTraversalPolicy
    extends java.awt.ContainerOrderFocusTraversalPolicy
{
    public boolean accept(Component aComponent) {
        return super.accept(aComponent);
    }
}