Java example source code file (Container.java)

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Java - Java tags/keywords

accessible, awt, component, container, containerevent, containerpeer, dimension, drag, drop, illegalargumentexception, javabean, layoutmanager2, lightweightpeer, mouseevent, objectstreamfield, override, point, security, sundroptargetevent, util

The Container.java Java example source code

/*
 * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package java.awt;

import java.awt.dnd.DropTarget;

import java.awt.event.*;

import java.awt.peer.ContainerPeer;
import java.awt.peer.ComponentPeer;
import java.awt.peer.LightweightPeer;

import java.beans.PropertyChangeListener;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamField;
import java.io.PrintStream;
import java.io.PrintWriter;

import java.security.AccessController;

import java.util.EventListener;
import java.util.HashSet;
import java.util.Set;

import javax.accessibility.*;

import sun.util.logging.PlatformLogger;

import sun.awt.AppContext;
import sun.awt.AWTAccessor;
import sun.awt.CausedFocusEvent;
import sun.awt.PeerEvent;
import sun.awt.SunToolkit;

import sun.awt.dnd.SunDropTargetEvent;

import sun.java2d.pipe.Region;

import sun.security.action.GetBooleanAction;

/**
 * A generic Abstract Window Toolkit(AWT) container object is a component
 * that can contain other AWT components.
 * <p>
 * Components added to a container are tracked in a list.  The order
 * of the list will define the components' front-to-back stacking order
 * within the container.  If no index is specified when adding a
 * component to a container, it will be added to the end of the list
 * (and hence to the bottom of the stacking order).
 * <p>
 * <b>Note: For details on the focus subsystem, see
 * <a href="http://docs.oracle.com/javase/tutorial/uiswing/misc/focus.html">
 * How to Use the Focus Subsystem</a>,
 * a section in <em>The Java Tutorial, and the
 * <a href="../../java/awt/doc-files/FocusSpec.html">Focus Specification
 * for more information.
 *
 * @author      Arthur van Hoff
 * @author      Sami Shaio
 * @see       #add(java.awt.Component, int)
 * @see       #getComponent(int)
 * @see       LayoutManager
 * @since     JDK1.0
 */
public class Container extends Component {

    private static final PlatformLogger log = PlatformLogger.getLogger("java.awt.Container");
    private static final PlatformLogger eventLog = PlatformLogger.getLogger("java.awt.event.Container");

    private static final Component[] EMPTY_ARRAY = new Component[0];

    /**
     * The components in this container.
     * @see #add
     * @see #getComponents
     */
    private java.util.List<Component> component = new java.util.ArrayList();

    /**
     * Layout manager for this container.
     * @see #doLayout
     * @see #setLayout
     * @see #getLayout
     */
    LayoutManager layoutMgr;

    /**
     * Event router for lightweight components.  If this container
     * is native, this dispatcher takes care of forwarding and
     * retargeting the events to lightweight components contained
     * (if any).
     */
    private LightweightDispatcher dispatcher;

    /**
     * The focus traversal policy that will manage keyboard traversal of this
     * Container's children, if this Container is a focus cycle root. If the
     * value is null, this Container inherits its policy from its focus-cycle-
     * root ancestor. If all such ancestors of this Container have null
     * policies, then the current KeyboardFocusManager's default policy is
     * used. If the value is non-null, this policy will be inherited by all
     * focus-cycle-root children that have no keyboard-traversal policy of
     * their own (as will, recursively, their focus-cycle-root children).
     * <p>
     * If this Container is not a focus cycle root, the value will be
     * remembered, but will not be used or inherited by this or any other
     * Containers until this Container is made a focus cycle root.
     *
     * @see #setFocusTraversalPolicy
     * @see #getFocusTraversalPolicy
     * @since 1.4
     */
    private transient FocusTraversalPolicy focusTraversalPolicy;

    /**
     * Indicates whether this Component is the root of a focus traversal cycle.
     * Once focus enters a traversal cycle, typically it cannot leave it via
     * focus traversal unless one of the up- or down-cycle keys is pressed.
     * Normal traversal is limited to this Container, and all of this
     * Container's descendants that are not descendants of inferior focus cycle
     * roots.
     *
     * @see #setFocusCycleRoot
     * @see #isFocusCycleRoot
     * @since 1.4
     */
    private boolean focusCycleRoot = false;


    /**
     * Stores the value of focusTraversalPolicyProvider property.
     * @since 1.5
     * @see #setFocusTraversalPolicyProvider
     */
    private boolean focusTraversalPolicyProvider;

    // keeps track of the threads that are printing this component
    private transient Set<Thread> printingThreads;
    // True if there is at least one thread that's printing this component
    private transient boolean printing = false;

    transient ContainerListener containerListener;

    /* HierarchyListener and HierarchyBoundsListener support */
    transient int listeningChildren;
    transient int listeningBoundsChildren;
    transient int descendantsCount;

    /* Non-opaque window support -- see Window.setLayersOpaque */
    transient Color preserveBackgroundColor = null;

    /**
     * JDK 1.1 serialVersionUID
     */
    private static final long serialVersionUID = 4613797578919906343L;

    /**
     * A constant which toggles one of the controllable behaviors
     * of <code>getMouseEventTarget. It is used to specify whether
     * the method can return the Container on which it is originally called
     * in case if none of its children are the current mouse event targets.
     *
     * @see #getMouseEventTarget(int, int, boolean)
     */
    static final boolean INCLUDE_SELF = true;

    /**
     * A constant which toggles one of the controllable behaviors
     * of <code>getMouseEventTarget. It is used to specify whether
     * the method should search only lightweight components.
     *
     * @see #getMouseEventTarget(int, int, boolean)
     */
    static final boolean SEARCH_HEAVYWEIGHTS = true;

    /*
     * Number of HW or LW components in this container (including
     * all descendant containers).
     */
    private transient int numOfHWComponents = 0;
    private transient int numOfLWComponents = 0;

    private static final PlatformLogger mixingLog = PlatformLogger.getLogger("java.awt.mixing.Container");

    /**
     * @serialField ncomponents                     int
     *       The number of components in this container.
     *       This value can be null.
     * @serialField component                       Component[]
     *       The components in this container.
     * @serialField layoutMgr                       LayoutManager
     *       Layout manager for this container.
     * @serialField dispatcher                      LightweightDispatcher
     *       Event router for lightweight components.  If this container
     *       is native, this dispatcher takes care of forwarding and
     *       retargeting the events to lightweight components contained
     *       (if any).
     * @serialField maxSize                         Dimension
     *       Maximum size of this Container.
     * @serialField focusCycleRoot                  boolean
     *       Indicates whether this Component is the root of a focus traversal cycle.
     *       Once focus enters a traversal cycle, typically it cannot leave it via
     *       focus traversal unless one of the up- or down-cycle keys is pressed.
     *       Normal traversal is limited to this Container, and all of this
     *       Container's descendants that are not descendants of inferior focus cycle
     *       roots.
     * @serialField containerSerializedDataVersion  int
     *       Container Serial Data Version.
     * @serialField focusTraversalPolicyProvider    boolean
     *       Stores the value of focusTraversalPolicyProvider property.
     */
    private static final ObjectStreamField[] serialPersistentFields = {
        new ObjectStreamField("ncomponents", Integer.TYPE),
        new ObjectStreamField("component", Component[].class),
        new ObjectStreamField("layoutMgr", LayoutManager.class),
        new ObjectStreamField("dispatcher", LightweightDispatcher.class),
        new ObjectStreamField("maxSize", Dimension.class),
        new ObjectStreamField("focusCycleRoot", Boolean.TYPE),
        new ObjectStreamField("containerSerializedDataVersion", Integer.TYPE),
        new ObjectStreamField("focusTraversalPolicyProvider", Boolean.TYPE),
    };

    static {
        /* ensure that the necessary native libraries are loaded */
        Toolkit.loadLibraries();
        if (!GraphicsEnvironment.isHeadless()) {
            initIDs();
        }

        AWTAccessor.setContainerAccessor(new AWTAccessor.ContainerAccessor() {
            @Override
            public void validateUnconditionally(Container cont) {
                cont.validateUnconditionally();
            }

            @Override
            public Component findComponentAt(Container cont, int x, int y,
                    boolean ignoreEnabled) {
                return cont.findComponentAt(x, y, ignoreEnabled);
            }
        });
    }

    /**
     * Initialize JNI field and method IDs for fields that may be
       called from C.
     */
    private static native void initIDs();

    /**
     * Constructs a new Container. Containers can be extended directly,
     * but are lightweight in this case and must be contained by a parent
     * somewhere higher up in the component tree that is native.
     * (such as Frame for example).
     */
    public Container() {
    }
    @SuppressWarnings({"unchecked","rawtypes"})
    void initializeFocusTraversalKeys() {
        focusTraversalKeys = new Set[4];
    }

    /**
     * Gets the number of components in this panel.
     * <p>
     * Note: This method should be called under AWT tree lock.
     *
     * @return    the number of components in this panel.
     * @see       #getComponent
     * @since     JDK1.1
     * @see Component#getTreeLock()
     */
    public int getComponentCount() {
        return countComponents();
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by getComponentCount().
     */
    @Deprecated
    public int countComponents() {
        // This method is not synchronized under AWT tree lock.
        // Instead, the calling code is responsible for the
        // synchronization. See 6784816 for details.
        return component.size();
    }

    /**
     * Gets the nth component in this container.
     * <p>
     * Note: This method should be called under AWT tree lock.
     *
     * @param      n   the index of the component to get.
     * @return     the n<sup>th component in this container.
     * @exception  ArrayIndexOutOfBoundsException
     *                 if the n<sup>th value does not exist.
     * @see Component#getTreeLock()
     */
    public Component getComponent(int n) {
        // This method is not synchronized under AWT tree lock.
        // Instead, the calling code is responsible for the
        // synchronization. See 6784816 for details.
        try {
            return component.get(n);
        } catch (IndexOutOfBoundsException z) {
            throw new ArrayIndexOutOfBoundsException("No such child: " + n);
        }
    }

    /**
     * Gets all the components in this container.
     * <p>
     * Note: This method should be called under AWT tree lock.
     *
     * @return    an array of all the components in this container.
     * @see Component#getTreeLock()
     */
    public Component[] getComponents() {
        // This method is not synchronized under AWT tree lock.
        // Instead, the calling code is responsible for the
        // synchronization. See 6784816 for details.
        return getComponents_NoClientCode();
    }

    // NOTE: This method may be called by privileged threads.
    //       This functionality is implemented in a package-private method
    //       to insure that it cannot be overridden by client subclasses.
    //       DO NOT INVOKE CLIENT CODE ON THIS THREAD!
    final Component[] getComponents_NoClientCode() {
        return component.toArray(EMPTY_ARRAY);
    }

    /*
     * Wrapper for getComponents() method with a proper synchronization.
     */
    Component[] getComponentsSync() {
        synchronized (getTreeLock()) {
            return getComponents();
        }
    }

    /**
     * Determines the insets of this container, which indicate the size
     * of the container's border.
     * <p>
     * A <code>Frame object, for example, has a top inset that
     * corresponds to the height of the frame's title bar.
     * @return    the insets of this container.
     * @see       Insets
     * @see       LayoutManager
     * @since     JDK1.1
     */
    public Insets getInsets() {
        return insets();
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by <code>getInsets().
     */
    @Deprecated
    public Insets insets() {
        ComponentPeer peer = this.peer;
        if (peer instanceof ContainerPeer) {
            ContainerPeer cpeer = (ContainerPeer)peer;
            return (Insets)cpeer.getInsets().clone();
        }
        return new Insets(0, 0, 0, 0);
    }

    /**
     * Appends the specified component to the end of this container.
     * This is a convenience method for {@link #addImpl}.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy. If the container has already been
     * displayed, the hierarchy must be validated thereafter in order to
     * display the added component.
     *
     * @param     comp   the component to be added
     * @exception NullPointerException if {@code comp} is {@code null}
     * @see #addImpl
     * @see #invalidate
     * @see #validate
     * @see javax.swing.JComponent#revalidate()
     * @return    the component argument
     */
    public Component add(Component comp) {
        addImpl(comp, null, -1);
        return comp;
    }

    /**
     * Adds the specified component to this container.
     * This is a convenience method for {@link #addImpl}.
     * <p>
     * This method is obsolete as of 1.1.  Please use the
     * method <code>add(Component, Object) instead.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy. If the container has already been
     * displayed, the hierarchy must be validated thereafter in order to
     * display the added component.
     *
     * @exception NullPointerException if {@code comp} is {@code null}
     * @see #add(Component, Object)
     * @see #invalidate
     */
    public Component add(String name, Component comp) {
        addImpl(comp, name, -1);
        return comp;
    }

    /**
     * Adds the specified component to this container at the given
     * position.
     * This is a convenience method for {@link #addImpl}.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy. If the container has already been
     * displayed, the hierarchy must be validated thereafter in order to
     * display the added component.
     *
     *
     * @param     comp   the component to be added
     * @param     index    the position at which to insert the component,
     *                   or <code>-1 to append the component to the end
     * @exception NullPointerException if {@code comp} is {@code null}
     * @exception IllegalArgumentException if {@code index} is invalid (see
     *            {@link #addImpl} for details)
     * @return    the component <code>comp
     * @see #addImpl
     * @see #remove
     * @see #invalidate
     * @see #validate
     * @see javax.swing.JComponent#revalidate()
     */
    public Component add(Component comp, int index) {
        addImpl(comp, null, index);
        return comp;
    }

    /**
     * Checks that the component
     * isn't supposed to be added into itself.
     */
    private void checkAddToSelf(Component comp){
        if (comp instanceof Container) {
            for (Container cn = this; cn != null; cn=cn.parent) {
                if (cn == comp) {
                    throw new IllegalArgumentException("adding container's parent to itself");
                }
            }
        }
    }

    /**
     * Checks that the component is not a Window instance.
     */
    private void checkNotAWindow(Component comp){
        if (comp instanceof Window) {
            throw new IllegalArgumentException("adding a window to a container");
        }
    }

    /**
     * Checks that the component comp can be added to this container
     * Checks :  index in bounds of container's size,
     * comp is not one of this container's parents,
     * and comp is not a window.
     * Comp and container must be on the same GraphicsDevice.
     * if comp is container, all sub-components must be on
     * same GraphicsDevice.
     *
     * @since 1.5
     */
    private void checkAdding(Component comp, int index) {
        checkTreeLock();

        GraphicsConfiguration thisGC = getGraphicsConfiguration();

        if (index > component.size() || index < 0) {
            throw new IllegalArgumentException("illegal component position");
        }
        if (comp.parent == this) {
            if (index == component.size()) {
                throw new IllegalArgumentException("illegal component position " +
                                                   index + " should be less then " + component.size());
            }
        }
        checkAddToSelf(comp);
        checkNotAWindow(comp);

        Window thisTopLevel = getContainingWindow();
        Window compTopLevel = comp.getContainingWindow();
        if (thisTopLevel != compTopLevel) {
            throw new IllegalArgumentException("component and container should be in the same top-level window");
        }
        if (thisGC != null) {
            comp.checkGD(thisGC.getDevice().getIDstring());
        }
    }

    /**
     * Removes component comp from this container without making unneccessary changes
     * and generating unneccessary events. This function intended to perform optimized
     * remove, for example, if newParent and current parent are the same it just changes
     * index without calling removeNotify.
     * Note: Should be called while holding treeLock
     * Returns whether removeNotify was invoked
     * @since: 1.5
     */
    private boolean removeDelicately(Component comp, Container newParent, int newIndex) {
        checkTreeLock();

        int index = getComponentZOrder(comp);
        boolean needRemoveNotify = isRemoveNotifyNeeded(comp, this, newParent);
        if (needRemoveNotify) {
            comp.removeNotify();
        }
        if (newParent != this) {
            if (layoutMgr != null) {
                layoutMgr.removeLayoutComponent(comp);
            }
            adjustListeningChildren(AWTEvent.HIERARCHY_EVENT_MASK,
                                    -comp.numListening(AWTEvent.HIERARCHY_EVENT_MASK));
            adjustListeningChildren(AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK,
                                    -comp.numListening(AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK));
            adjustDescendants(-(comp.countHierarchyMembers()));

            comp.parent = null;
            if (needRemoveNotify) {
                comp.setGraphicsConfiguration(null);
            }
            component.remove(index);

            invalidateIfValid();
        } else {
            // We should remove component and then
            // add it by the newIndex without newIndex decrement if even we shift components to the left
            // after remove. Consult the rules below:
            // 2->4: 012345 -> 013425, 2->5: 012345 -> 013452
            // 4->2: 012345 -> 014235
            component.remove(index);
            component.add(newIndex, comp);
        }
        if (comp.parent == null) { // was actually removed
            if (containerListener != null ||
                (eventMask & AWTEvent.CONTAINER_EVENT_MASK) != 0 ||
                Toolkit.enabledOnToolkit(AWTEvent.CONTAINER_EVENT_MASK)) {
                ContainerEvent e = new ContainerEvent(this,
                                                      ContainerEvent.COMPONENT_REMOVED,
                                                      comp);
                dispatchEvent(e);

            }
            comp.createHierarchyEvents(HierarchyEvent.HIERARCHY_CHANGED, comp,
                                       this, HierarchyEvent.PARENT_CHANGED,
                                       Toolkit.enabledOnToolkit(AWTEvent.HIERARCHY_EVENT_MASK));
            if (peer != null && layoutMgr == null && isVisible()) {
                updateCursorImmediately();
            }
        }
        return needRemoveNotify;
    }

    /**
     * Checks whether this container can contain component which is focus owner.
     * Verifies that container is enable and showing, and if it is focus cycle root
     * its FTP allows component to be focus owner
     * @since 1.5
     */
    boolean canContainFocusOwner(Component focusOwnerCandidate) {
        if (!(isEnabled() && isDisplayable()
              && isVisible() && isFocusable()))
        {
            return false;
        }
        if (isFocusCycleRoot()) {
            FocusTraversalPolicy policy = getFocusTraversalPolicy();
            if (policy instanceof DefaultFocusTraversalPolicy) {
                if (!((DefaultFocusTraversalPolicy)policy).accept(focusOwnerCandidate)) {
                    return false;
                }
            }
        }
        synchronized(getTreeLock()) {
            if (parent != null) {
                return parent.canContainFocusOwner(focusOwnerCandidate);
            }
        }
        return true;
    }

    /**
     * Checks whether or not this container has heavyweight children.
     * Note: Should be called while holding tree lock
     * @return true if there is at least one heavyweight children in a container, false otherwise
     * @since 1.5
     */
    final boolean hasHeavyweightDescendants() {
        checkTreeLock();
        return numOfHWComponents > 0;
    }

    /**
     * Checks whether or not this container has lightweight children.
     * Note: Should be called while holding tree lock
     * @return true if there is at least one lightweight children in a container, false otherwise
     * @since 1.7
     */
    final boolean hasLightweightDescendants() {
        checkTreeLock();
        return numOfLWComponents > 0;
    }

    /**
     * Returns closest heavyweight component to this container. If this container is heavyweight
     * returns this.
     * @since 1.5
     */
    Container getHeavyweightContainer() {
        checkTreeLock();
        if (peer != null && !(peer instanceof LightweightPeer)) {
            return this;
        } else {
            return getNativeContainer();
        }
    }

    /**
     * Detects whether or not remove from current parent and adding to new parent requires call of
     * removeNotify on the component. Since removeNotify destroys native window this might (not)
     * be required. For example, if new container and old containers are the same we don't need to
     * destroy native window.
     * @since: 1.5
     */
    private static boolean isRemoveNotifyNeeded(Component comp, Container oldContainer, Container newContainer) {
        if (oldContainer == null) { // Component didn't have parent - no removeNotify
            return false;
        }
        if (comp.peer == null) { // Component didn't have peer - no removeNotify
            return false;
        }
        if (newContainer.peer == null) {
            // Component has peer but new Container doesn't - call removeNotify
            return true;
        }

        // If component is lightweight non-Container or lightweight Container with all but heavyweight
        // children there is no need to call remove notify
        if (comp.isLightweight()) {
            boolean isContainer = comp instanceof Container;

            if (!isContainer || (isContainer && !((Container)comp).hasHeavyweightDescendants())) {
                return false;
            }
        }

        // If this point is reached, then the comp is either a HW or a LW container with HW descendants.

        // All three components have peers, check for peer change
        Container newNativeContainer = oldContainer.getHeavyweightContainer();
        Container oldNativeContainer = newContainer.getHeavyweightContainer();
        if (newNativeContainer != oldNativeContainer) {
            // Native containers change - check whether or not current platform supports
            // changing of widget hierarchy on native level without recreation.
            // The current implementation forbids reparenting of LW containers with HW descendants
            // into another native container w/o destroying the peers. Actually such an operation
            // is quite rare. If we ever need to save the peers, we'll have to slightly change the
            // addDelicately() method in order to handle such LW containers recursively, reparenting
            // each HW descendant independently.
            return !comp.peer.isReparentSupported();
        } else {
            return false;
        }
    }

    /**
     * Moves the specified component to the specified z-order index in
     * the container. The z-order determines the order that components
     * are painted; the component with the highest z-order paints first
     * and the component with the lowest z-order paints last.
     * Where components overlap, the component with the lower
     * z-order paints over the component with the higher z-order.
     * <p>
     * If the component is a child of some other container, it is
     * removed from that container before being added to this container.
     * The important difference between this method and
     * <code>java.awt.Container.add(Component, int) is that this method
     * doesn't call <code>removeNotify on the component while
     * removing it from its previous container unless necessary and when
     * allowed by the underlying native windowing system. This way, if the
     * component has the keyboard focus, it maintains the focus when
     * moved to the new position.
     * <p>
     * This property is guaranteed to apply only to lightweight
     * non-<code>Container components.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy.
     * <p>
     * <b>Note: Not all platforms support changing the z-order of
     * heavyweight components from one container into another without
     * the call to <code>removeNotify. There is no way to detect
     * whether a platform supports this, so developers shouldn't make
     * any assumptions.
     *
     * @param     comp the component to be moved
     * @param     index the position in the container's list to
     *            insert the component, where <code>getComponentCount()
     *            appends to the end
     * @exception NullPointerException if <code>comp is
     *            <code>null
     * @exception IllegalArgumentException if <code>comp is one of the
     *            container's parents
     * @exception IllegalArgumentException if <code>index is not in
     *            the range <code>[0, getComponentCount()] for moving
     *            between containers, or not in the range
     *            <code>[0, getComponentCount()-1] for moving inside
     *            a container
     * @exception IllegalArgumentException if adding a container to itself
     * @exception IllegalArgumentException if adding a <code>Window
     *            to a container
     * @see #getComponentZOrder(java.awt.Component)
     * @see #invalidate
     * @since 1.5
     */
    public void setComponentZOrder(Component comp, int index) {
         synchronized (getTreeLock()) {
             // Store parent because remove will clear it
             Container curParent = comp.parent;
             int oldZindex = getComponentZOrder(comp);

             if (curParent == this && index == oldZindex) {
                 return;
             }
             checkAdding(comp, index);

             boolean peerRecreated = (curParent != null) ?
                 curParent.removeDelicately(comp, this, index) : false;

             addDelicately(comp, curParent, index);

             // If the oldZindex == -1, the component gets inserted,
             // rather than it changes its z-order.
             if (!peerRecreated && oldZindex != -1) {
                 // The new 'index' cannot be == -1.
                 // It gets checked at the checkAdding() method.
                 // Therefore both oldZIndex and index denote
                 // some existing positions at this point and
                 // this is actually a Z-order changing.
                 comp.mixOnZOrderChanging(oldZindex, index);
             }
         }
    }

    /**
     * Traverses the tree of components and reparents children heavyweight component
     * to new heavyweight parent.
     * @since 1.5
     */
    private void reparentTraverse(ContainerPeer parentPeer, Container child) {
        checkTreeLock();

        for (int i = 0; i < child.getComponentCount(); i++) {
            Component comp = child.getComponent(i);
            if (comp.isLightweight()) {
                // If components is lightweight check if it is container
                // If it is container it might contain heavyweight children we need to reparent
                if (comp instanceof Container) {
                    reparentTraverse(parentPeer, (Container)comp);
                }
            } else {
                // Q: Need to update NativeInLightFixer?
                comp.getPeer().reparent(parentPeer);
            }
        }
    }

    /**
     * Reparents child component peer to this container peer.
     * Container must be heavyweight.
     * @since 1.5
     */
    private void reparentChild(Component comp) {
        checkTreeLock();
        if (comp == null) {
            return;
        }
        if (comp.isLightweight()) {
            // If component is lightweight container we need to reparent all its explicit  heavyweight children
            if (comp instanceof Container) {
                // Traverse component's tree till depth-first until encountering heavyweight component
                reparentTraverse((ContainerPeer)getPeer(), (Container)comp);
            }
        } else {
            comp.getPeer().reparent((ContainerPeer)getPeer());
        }
    }

    /**
     * Adds component to this container. Tries to minimize side effects of this adding -
     * doesn't call remove notify if it is not required.
     * @since 1.5
     */
    private void addDelicately(Component comp, Container curParent, int index) {
        checkTreeLock();

        // Check if moving between containers
        if (curParent != this) {
            //index == -1 means add to the end.
            if (index == -1) {
                component.add(comp);
            } else {
                component.add(index, comp);
            }
            comp.parent = this;
            comp.setGraphicsConfiguration(getGraphicsConfiguration());

            adjustListeningChildren(AWTEvent.HIERARCHY_EVENT_MASK,
                                    comp.numListening(AWTEvent.HIERARCHY_EVENT_MASK));
            adjustListeningChildren(AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK,
                                    comp.numListening(AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK));
            adjustDescendants(comp.countHierarchyMembers());
        } else {
            if (index < component.size()) {
                component.set(index, comp);
            }
        }

        invalidateIfValid();
        if (peer != null) {
            if (comp.peer == null) { // Remove notify was called or it didn't have peer - create new one
                comp.addNotify();
            } else { // Both container and child have peers, it means child peer should be reparented.
                // In both cases we need to reparent native widgets.
                Container newNativeContainer = getHeavyweightContainer();
                Container oldNativeContainer = curParent.getHeavyweightContainer();
                if (oldNativeContainer != newNativeContainer) {
                    // Native container changed - need to reparent native widgets
                    newNativeContainer.reparentChild(comp);
                }
                comp.updateZOrder();

                if (!comp.isLightweight() && isLightweight()) {
                    // If component is heavyweight and one of the containers is lightweight
                    // the location of the component should be fixed.
                    comp.relocateComponent();
                }
            }
        }
        if (curParent != this) {
            /* Notify the layout manager of the added component. */
            if (layoutMgr != null) {
                if (layoutMgr instanceof LayoutManager2) {
                    ((LayoutManager2)layoutMgr).addLayoutComponent(comp, null);
                } else {
                    layoutMgr.addLayoutComponent(null, comp);
                }
            }
            if (containerListener != null ||
                (eventMask & AWTEvent.CONTAINER_EVENT_MASK) != 0 ||
                Toolkit.enabledOnToolkit(AWTEvent.CONTAINER_EVENT_MASK)) {
                ContainerEvent e = new ContainerEvent(this,
                                                      ContainerEvent.COMPONENT_ADDED,
                                                      comp);
                dispatchEvent(e);
            }
            comp.createHierarchyEvents(HierarchyEvent.HIERARCHY_CHANGED, comp,
                                       this, HierarchyEvent.PARENT_CHANGED,
                                       Toolkit.enabledOnToolkit(AWTEvent.HIERARCHY_EVENT_MASK));

            // If component is focus owner or parent container of focus owner check that after reparenting
            // focus owner moved out if new container prohibit this kind of focus owner.
            if (comp.isFocusOwner() && !comp.canBeFocusOwnerRecursively()) {
                comp.transferFocus();
            } else if (comp instanceof Container) {
                Component focusOwner = KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner();
                if (focusOwner != null && isParentOf(focusOwner) && !focusOwner.canBeFocusOwnerRecursively()) {
                    focusOwner.transferFocus();
                }
            }
        } else {
            comp.createHierarchyEvents(HierarchyEvent.HIERARCHY_CHANGED, comp,
                                       this, HierarchyEvent.HIERARCHY_CHANGED,
                                       Toolkit.enabledOnToolkit(AWTEvent.HIERARCHY_EVENT_MASK));
        }

        if (peer != null && layoutMgr == null && isVisible()) {
            updateCursorImmediately();
        }
    }

    /**
     * Returns the z-order index of the component inside the container.
     * The higher a component is in the z-order hierarchy, the lower
     * its index.  The component with the lowest z-order index is
     * painted last, above all other child components.
     *
     * @param comp the component being queried
     * @return  the z-order index of the component; otherwise
     *          returns -1 if the component is <code>null
     *          or doesn't belong to the container
     * @see #setComponentZOrder(java.awt.Component, int)
     * @since 1.5
     */
    public int getComponentZOrder(Component comp) {
        if (comp == null) {
            return -1;
        }
        synchronized(getTreeLock()) {
            // Quick check - container should be immediate parent of the component
            if (comp.parent != this) {
                return -1;
            }
            return component.indexOf(comp);
        }
    }

    /**
     * Adds the specified component to the end of this container.
     * Also notifies the layout manager to add the component to
     * this container's layout using the specified constraints object.
     * This is a convenience method for {@link #addImpl}.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy. If the container has already been
     * displayed, the hierarchy must be validated thereafter in order to
     * display the added component.
     *
     *
     * @param     comp the component to be added
     * @param     constraints an object expressing
     *                  layout constraints for this component
     * @exception NullPointerException if {@code comp} is {@code null}
     * @see #addImpl
     * @see #invalidate
     * @see #validate
     * @see javax.swing.JComponent#revalidate()
     * @see       LayoutManager
     * @since     JDK1.1
     */
    public void add(Component comp, Object constraints) {
        addImpl(comp, constraints, -1);
    }

    /**
     * Adds the specified component to this container with the specified
     * constraints at the specified index.  Also notifies the layout
     * manager to add the component to the this container's layout using
     * the specified constraints object.
     * This is a convenience method for {@link #addImpl}.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy. If the container has already been
     * displayed, the hierarchy must be validated thereafter in order to
     * display the added component.
     *
     *
     * @param comp the component to be added
     * @param constraints an object expressing layout constraints for this
     * @param index the position in the container's list at which to insert
     * the component; <code>-1 means insert at the end
     * component
     * @exception NullPointerException if {@code comp} is {@code null}
     * @exception IllegalArgumentException if {@code index} is invalid (see
     *            {@link #addImpl} for details)
     * @see #addImpl
     * @see #invalidate
     * @see #validate
     * @see javax.swing.JComponent#revalidate()
     * @see #remove
     * @see LayoutManager
     */
    public void add(Component comp, Object constraints, int index) {
       addImpl(comp, constraints, index);
    }

    /**
     * Adds the specified component to this container at the specified
     * index. This method also notifies the layout manager to add
     * the component to this container's layout using the specified
     * constraints object via the <code>addLayoutComponent
     * method.
     * <p>
     * The constraints are
     * defined by the particular layout manager being used.  For
     * example, the <code>BorderLayout class defines five
     * constraints: <code>BorderLayout.NORTH,
     * <code>BorderLayout.SOUTH, BorderLayout.EAST,
     * <code>BorderLayout.WEST, and BorderLayout.CENTER.
     * <p>
     * The <code>GridBagLayout class requires a
     * <code>GridBagConstraints object.  Failure to pass
     * the correct type of constraints object results in an
     * <code>IllegalArgumentException.
     * <p>
     * If the current layout manager implements {@code LayoutManager2}, then
     * {@link LayoutManager2#addLayoutComponent(Component,Object)} is invoked on
     * it. If the current layout manager does not implement
     * {@code LayoutManager2}, and constraints is a {@code String}, then
     * {@link LayoutManager#addLayoutComponent(String,Component)} is invoked on it.
     * <p>
     * If the component is not an ancestor of this container and has a non-null
     * parent, it is removed from its current parent before it is added to this
     * container.
     * <p>
     * This is the method to override if a program needs to track
     * every add request to a container as all other add methods defer
     * to this one. An overriding method should
     * usually include a call to the superclass's version of the method:
     *
     * <blockquote>
     * <code>super.addImpl(comp, constraints, index)
     * </blockquote>
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy. If the container has already been
     * displayed, the hierarchy must be validated thereafter in order to
     * display the added component.
     *
     * @param     comp       the component to be added
     * @param     constraints an object expressing layout constraints
     *                 for this component
     * @param     index the position in the container's list at which to
     *                 insert the component, where <code>-1
     *                 means append to the end
     * @exception IllegalArgumentException if {@code index} is invalid;
     *            if {@code comp} is a child of this container, the valid
     *            range is {@code [-1, getComponentCount()-1]}; if component is
     *            not a child of this container, the valid range is
     *            {@code [-1, getComponentCount()]}
     *
     * @exception IllegalArgumentException if {@code comp} is an ancestor of
     *                                     this container
     * @exception IllegalArgumentException if adding a window to a container
     * @exception NullPointerException if {@code comp} is {@code null}
     * @see       #add(Component)
     * @see       #add(Component, int)
     * @see       #add(Component, java.lang.Object)
     * @see #invalidate
     * @see       LayoutManager
     * @see       LayoutManager2
     * @since     JDK1.1
     */
    protected void addImpl(Component comp, Object constraints, int index) {
        synchronized (getTreeLock()) {
            /* Check for correct arguments:  index in bounds,
             * comp cannot be one of this container's parents,
             * and comp cannot be a window.
             * comp and container must be on the same GraphicsDevice.
             * if comp is container, all sub-components must be on
             * same GraphicsDevice.
             */
            GraphicsConfiguration thisGC = this.getGraphicsConfiguration();

            if (index > component.size() || (index < 0 && index != -1)) {
                throw new IllegalArgumentException(
                          "illegal component position");
            }
            checkAddToSelf(comp);
            checkNotAWindow(comp);
            if (thisGC != null) {
                comp.checkGD(thisGC.getDevice().getIDstring());
            }

            /* Reparent the component and tidy up the tree's state. */
            if (comp.parent != null) {
                comp.parent.remove(comp);
                    if (index > component.size()) {
                        throw new IllegalArgumentException("illegal component position");
                    }
            }

            //index == -1 means add to the end.
            if (index == -1) {
                component.add(comp);
            } else {
                component.add(index, comp);
            }
            comp.parent = this;
            comp.setGraphicsConfiguration(thisGC);

            adjustListeningChildren(AWTEvent.HIERARCHY_EVENT_MASK,
                comp.numListening(AWTEvent.HIERARCHY_EVENT_MASK));
            adjustListeningChildren(AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK,
                comp.numListening(AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK));
            adjustDescendants(comp.countHierarchyMembers());

            invalidateIfValid();
            if (peer != null) {
                comp.addNotify();
            }

            /* Notify the layout manager of the added component. */
            if (layoutMgr != null) {
                if (layoutMgr instanceof LayoutManager2) {
                    ((LayoutManager2)layoutMgr).addLayoutComponent(comp, constraints);
                } else if (constraints instanceof String) {
                    layoutMgr.addLayoutComponent((String)constraints, comp);
                }
            }
            if (containerListener != null ||
                (eventMask & AWTEvent.CONTAINER_EVENT_MASK) != 0 ||
                Toolkit.enabledOnToolkit(AWTEvent.CONTAINER_EVENT_MASK)) {
                ContainerEvent e = new ContainerEvent(this,
                                     ContainerEvent.COMPONENT_ADDED,
                                     comp);
                dispatchEvent(e);
            }

            comp.createHierarchyEvents(HierarchyEvent.HIERARCHY_CHANGED, comp,
                                       this, HierarchyEvent.PARENT_CHANGED,
                                       Toolkit.enabledOnToolkit(AWTEvent.HIERARCHY_EVENT_MASK));
            if (peer != null && layoutMgr == null && isVisible()) {
                updateCursorImmediately();
            }
        }
    }

    @Override
    boolean updateGraphicsData(GraphicsConfiguration gc) {
        checkTreeLock();

        boolean ret = super.updateGraphicsData(gc);

        for (Component comp : component) {
            if (comp != null) {
                ret |= comp.updateGraphicsData(gc);
            }
        }
        return ret;
    }

    /**
     * Checks that all Components that this Container contains are on
     * the same GraphicsDevice as this Container.  If not, throws an
     * IllegalArgumentException.
     */
    void checkGD(String stringID) {
        for (Component comp : component) {
            if (comp != null) {
                comp.checkGD(stringID);
            }
        }
    }

    /**
     * Removes the component, specified by <code>index,
     * from this container.
     * This method also notifies the layout manager to remove the
     * component from this container's layout via the
     * <code>removeLayoutComponent method.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy. If the container has already been
     * displayed, the hierarchy must be validated thereafter in order to
     * reflect the changes.
     *
     *
     * @param     index   the index of the component to be removed
     * @throws ArrayIndexOutOfBoundsException if {@code index} is not in
     *         range {@code [0, getComponentCount()-1]}
     * @see #add
     * @see #invalidate
     * @see #validate
     * @see #getComponentCount
     * @since JDK1.1
     */
    public void remove(int index) {
        synchronized (getTreeLock()) {
            if (index < 0  || index >= component.size()) {
                throw new ArrayIndexOutOfBoundsException(index);
            }
            Component comp = component.get(index);
            if (peer != null) {
                comp.removeNotify();
            }
            if (layoutMgr != null) {
                layoutMgr.removeLayoutComponent(comp);
            }

            adjustListeningChildren(AWTEvent.HIERARCHY_EVENT_MASK,
                -comp.numListening(AWTEvent.HIERARCHY_EVENT_MASK));
            adjustListeningChildren(AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK,
                -comp.numListening(AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK));
            adjustDescendants(-(comp.countHierarchyMembers()));

            comp.parent = null;
            component.remove(index);
            comp.setGraphicsConfiguration(null);

            invalidateIfValid();
            if (containerListener != null ||
                (eventMask & AWTEvent.CONTAINER_EVENT_MASK) != 0 ||
                Toolkit.enabledOnToolkit(AWTEvent.CONTAINER_EVENT_MASK)) {
                ContainerEvent e = new ContainerEvent(this,
                                     ContainerEvent.COMPONENT_REMOVED,
                                     comp);
                dispatchEvent(e);
            }

            comp.createHierarchyEvents(HierarchyEvent.HIERARCHY_CHANGED, comp,
                                       this, HierarchyEvent.PARENT_CHANGED,
                                       Toolkit.enabledOnToolkit(AWTEvent.HIERARCHY_EVENT_MASK));
            if (peer != null && layoutMgr == null && isVisible()) {
                updateCursorImmediately();
            }
        }
    }

    /**
     * Removes the specified component from this container.
     * This method also notifies the layout manager to remove the
     * component from this container's layout via the
     * <code>removeLayoutComponent method.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy. If the container has already been
     * displayed, the hierarchy must be validated thereafter in order to
     * reflect the changes.
     *
     * @param comp the component to be removed
     * @throws NullPointerException if {@code comp} is {@code null}
     * @see #add
     * @see #invalidate
     * @see #validate
     * @see #remove(int)
     */
    public void remove(Component comp) {
        synchronized (getTreeLock()) {
            if (comp.parent == this)  {
                int index = component.indexOf(comp);
                if (index >= 0) {
                    remove(index);
                }
            }
        }
    }

    /**
     * Removes all the components from this container.
     * This method also notifies the layout manager to remove the
     * components from this container's layout via the
     * <code>removeLayoutComponent method.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy. If the container has already been
     * displayed, the hierarchy must be validated thereafter in order to
     * reflect the changes.
     *
     * @see #add
     * @see #remove
     * @see #invalidate
     */
    public void removeAll() {
        synchronized (getTreeLock()) {
            adjustListeningChildren(AWTEvent.HIERARCHY_EVENT_MASK,
                                    -listeningChildren);
            adjustListeningChildren(AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK,
                                    -listeningBoundsChildren);
            adjustDescendants(-descendantsCount);

            while (!component.isEmpty()) {
                Component comp = component.remove(component.size()-1);

                if (peer != null) {
                    comp.removeNotify();
                }
                if (layoutMgr != null) {
                    layoutMgr.removeLayoutComponent(comp);
                }
                comp.parent = null;
                comp.setGraphicsConfiguration(null);
                if (containerListener != null ||
                   (eventMask & AWTEvent.CONTAINER_EVENT_MASK) != 0 ||
                    Toolkit.enabledOnToolkit(AWTEvent.CONTAINER_EVENT_MASK)) {
                    ContainerEvent e = new ContainerEvent(this,
                                     ContainerEvent.COMPONENT_REMOVED,
                                     comp);
                    dispatchEvent(e);
                }

                comp.createHierarchyEvents(HierarchyEvent.HIERARCHY_CHANGED,
                                           comp, this,
                                           HierarchyEvent.PARENT_CHANGED,
                                           Toolkit.enabledOnToolkit(AWTEvent.HIERARCHY_EVENT_MASK));
            }
            if (peer != null && layoutMgr == null && isVisible()) {
                updateCursorImmediately();
            }
            invalidateIfValid();
        }
    }

    // Should only be called while holding tree lock
    int numListening(long mask) {
        int superListening = super.numListening(mask);

        if (mask == AWTEvent.HIERARCHY_EVENT_MASK) {
            if (eventLog.isLoggable(PlatformLogger.Level.FINE)) {
                // Verify listeningChildren is correct
                int sum = 0;
                for (Component comp : component) {
                    sum += comp.numListening(mask);
                }
                if (listeningChildren != sum) {
                    eventLog.fine("Assertion (listeningChildren == sum) failed");
                }
            }
            return listeningChildren + superListening;
        } else if (mask == AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK) {
            if (eventLog.isLoggable(PlatformLogger.Level.FINE)) {
                // Verify listeningBoundsChildren is correct
                int sum = 0;
                for (Component comp : component) {
                    sum += comp.numListening(mask);
                }
                if (listeningBoundsChildren != sum) {
                    eventLog.fine("Assertion (listeningBoundsChildren == sum) failed");
                }
            }
            return listeningBoundsChildren + superListening;
        } else {
            // assert false;
            if (eventLog.isLoggable(PlatformLogger.Level.FINE)) {
                eventLog.fine("This code must never be reached");
            }
            return superListening;
        }
    }

    // Should only be called while holding tree lock
    void adjustListeningChildren(long mask, int num) {
        if (eventLog.isLoggable(PlatformLogger.Level.FINE)) {
            boolean toAssert = (mask == AWTEvent.HIERARCHY_EVENT_MASK ||
                                mask == AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK ||
                                mask == (AWTEvent.HIERARCHY_EVENT_MASK |
                                         AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK));
            if (!toAssert) {
                eventLog.fine("Assertion failed");
            }
        }

        if (num == 0)
            return;

        if ((mask & AWTEvent.HIERARCHY_EVENT_MASK) != 0) {
            listeningChildren += num;
        }
        if ((mask & AWTEvent.HIERARCHY_BOUNDS_EVENT_MASK) != 0) {
            listeningBoundsChildren += num;
        }

        adjustListeningChildrenOnParent(mask, num);
    }

    // Should only be called while holding tree lock
    void adjustDescendants(int num) {
        if (num == 0)
            return;

        descendantsCount += num;
        adjustDecendantsOnParent(num);
    }

    // Should only be called while holding tree lock
    void adjustDecendantsOnParent(int num) {
        if (parent != null) {
            parent.adjustDescendants(num);
        }
    }

    // Should only be called while holding tree lock
    int countHierarchyMembers() {
        if (log.isLoggable(PlatformLogger.Level.FINE)) {
            // Verify descendantsCount is correct
            int sum = 0;
            for (Component comp : component) {
                sum += comp.countHierarchyMembers();
            }
            if (descendantsCount != sum) {
                log.fine("Assertion (descendantsCount == sum) failed");
            }
        }
        return descendantsCount + 1;
    }

    private int getListenersCount(int id, boolean enabledOnToolkit) {
        checkTreeLock();
        if (enabledOnToolkit) {
            return descendantsCount;
        }
        switch (id) {
          case HierarchyEvent.HIERARCHY_CHANGED:
            return listeningChildren;
          case HierarchyEvent.ANCESTOR_MOVED:
          case HierarchyEvent.ANCESTOR_RESIZED:
            return listeningBoundsChildren;
          default:
            return 0;
        }
    }

    final int createHierarchyEvents(int id, Component changed,
        Container changedParent, long changeFlags, boolean enabledOnToolkit)
    {
        checkTreeLock();
        int listeners = getListenersCount(id, enabledOnToolkit);

        for (int count = listeners, i = 0; count > 0; i++) {
            count -= component.get(i).createHierarchyEvents(id, changed,
                changedParent, changeFlags, enabledOnToolkit);
        }
        return listeners +
            super.createHierarchyEvents(id, changed, changedParent,
                                        changeFlags, enabledOnToolkit);
    }

    final void createChildHierarchyEvents(int id, long changeFlags,
        boolean enabledOnToolkit)
    {
        checkTreeLock();
        if (component.isEmpty()) {
            return;
        }
        int listeners = getListenersCount(id, enabledOnToolkit);

        for (int count = listeners, i = 0; count > 0; i++) {
            count -= component.get(i).createHierarchyEvents(id, this, parent,
                changeFlags, enabledOnToolkit);
        }
    }

    /**
     * Gets the layout manager for this container.
     * @see #doLayout
     * @see #setLayout
     */
    public LayoutManager getLayout() {
        return layoutMgr;
    }

    /**
     * Sets the layout manager for this container.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy.
     *
     * @param mgr the specified layout manager
     * @see #doLayout
     * @see #getLayout
     * @see #invalidate
     */
    public void setLayout(LayoutManager mgr) {
        layoutMgr = mgr;
        invalidateIfValid();
    }

    /**
     * Causes this container to lay out its components.  Most programs
     * should not call this method directly, but should invoke
     * the <code>validate method instead.
     * @see LayoutManager#layoutContainer
     * @see #setLayout
     * @see #validate
     * @since JDK1.1
     */
    public void doLayout() {
        layout();
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by <code>doLayout().
     */
    @Deprecated
    public void layout() {
        LayoutManager layoutMgr = this.layoutMgr;
        if (layoutMgr != null) {
            layoutMgr.layoutContainer(this);
        }
    }

    /**
     * Indicates if this container is a <i>validate root.
     * <p>
     * Layout-related changes, such as bounds of the validate root descendants,
     * do not affect the layout of the validate root parent. This peculiarity
     * enables the {@code invalidate()} method to stop invalidating the
     * component hierarchy when the method encounters a validate root. However,
     * to preserve backward compatibility this new optimized behavior is
     * enabled only when the {@code java.awt.smartInvalidate} system property
     * value is set to {@code true}.
     * <p>
     * If a component hierarchy contains validate roots and the new optimized
     * {@code invalidate()} behavior is enabled, the {@code validate()} method
     * must be invoked on the validate root of a previously invalidated
     * component to restore the validity of the hierarchy later. Otherwise,
     * calling the {@code validate()} method on the top-level container (such
     * as a {@code Frame} object) should be used to restore the validity of the
     * component hierarchy.
     * <p>
     * The {@code Window} class and the {@code Applet} class are the validate
     * roots in AWT.  Swing introduces more validate roots.
     *
     * @return whether this container is a validate root
     * @see #invalidate
     * @see java.awt.Component#invalidate
     * @see javax.swing.JComponent#isValidateRoot
     * @see javax.swing.JComponent#revalidate
     * @since 1.7
     */
    public boolean isValidateRoot() {
        return false;
    }

    private static final boolean isJavaAwtSmartInvalidate;
    static {
        // Don't lazy-read because every app uses invalidate()
        isJavaAwtSmartInvalidate = AccessController.doPrivileged(
                new GetBooleanAction("java.awt.smartInvalidate"));
    }

    /**
     * Invalidates the parent of the container unless the container
     * is a validate root.
     */
    @Override
    void invalidateParent() {
        if (!isJavaAwtSmartInvalidate || !isValidateRoot()) {
            super.invalidateParent();
        }
    }

    /**
     * Invalidates the container.
     * <p>
     * If the {@code LayoutManager} installed on this container is an instance
     * of the {@code LayoutManager2} interface, then
     * the {@link LayoutManager2#invalidateLayout(Container)} method is invoked
     * on it supplying this {@code Container} as the argument.
     * <p>
     * Afterwards this method marks this container invalid, and invalidates its
     * ancestors. See the {@link Component#invalidate} method for more details.
     *
     * @see #validate
     * @see #layout
     * @see LayoutManager2
     */
    @Override
    public void invalidate() {
        LayoutManager layoutMgr = this.layoutMgr;
        if (layoutMgr instanceof LayoutManager2) {
            LayoutManager2 lm = (LayoutManager2) layoutMgr;
            lm.invalidateLayout(this);
        }
        super.invalidate();
    }

    /**
     * Validates this container and all of its subcomponents.
     * <p>
     * Validating a container means laying out its subcomponents.
     * Layout-related changes, such as setting the bounds of a component, or
     * adding a component to the container, invalidate the container
     * automatically.  Note that the ancestors of the container may be
     * invalidated also (see {@link Component#invalidate} for details.)
     * Therefore, to restore the validity of the hierarchy, the {@code
     * validate()} method should be invoked on the top-most invalid
     * container of the hierarchy.
     * <p>
     * Validating the container may be a quite time-consuming operation. For
     * performance reasons a developer may postpone the validation of the
     * hierarchy till a set of layout-related operations completes, e.g. after
     * adding all the children to the container.
     * <p>
     * If this {@code Container} is not valid, this method invokes
     * the {@code validateTree} method and marks this {@code Container}
     * as valid. Otherwise, no action is performed.
     *
     * @see #add(java.awt.Component)
     * @see #invalidate
     * @see Container#isValidateRoot
     * @see javax.swing.JComponent#revalidate()
     * @see #validateTree
     */
    public void validate() {
        boolean updateCur = false;
        synchronized (getTreeLock()) {
            if ((!isValid() || descendUnconditionallyWhenValidating)
                    && peer != null)
            {
                ContainerPeer p = null;
                if (peer instanceof ContainerPeer) {
                    p = (ContainerPeer) peer;
                }
                if (p != null) {
                    p.beginValidate();
                }
                validateTree();
                if (p != null) {
                    p.endValidate();
                    // Avoid updating cursor if this is an internal call.
                    // See validateUnconditionally() for details.
                    if (!descendUnconditionallyWhenValidating) {
                        updateCur = isVisible();
                    }
                }
            }
        }
        if (updateCur) {
            updateCursorImmediately();
        }
    }

    /**
     * Indicates whether valid containers should also traverse their
     * children and call the validateTree() method on them.
     *
     * Synchronization: TreeLock.
     *
     * The field is allowed to be static as long as the TreeLock itself is
     * static.
     *
     * @see #validateUnconditionally()
     */
    private static boolean descendUnconditionallyWhenValidating = false;

    /**
     * Unconditionally validate the component hierarchy.
     */
    final void validateUnconditionally() {
        boolean updateCur = false;
        synchronized (getTreeLock()) {
            descendUnconditionallyWhenValidating = true;

            validate();
            if (peer instanceof ContainerPeer) {
                updateCur = isVisible();
            }

            descendUnconditionallyWhenValidating = false;
        }
        if (updateCur) {
            updateCursorImmediately();
        }
    }

    /**
     * Recursively descends the container tree and recomputes the
     * layout for any subtrees marked as needing it (those marked as
     * invalid).  Synchronization should be provided by the method
     * that calls this one:  <code>validate.
     *
     * @see #doLayout
     * @see #validate
     */
    protected void validateTree() {
        checkTreeLock();
        if (!isValid() || descendUnconditionallyWhenValidating) {
            if (peer instanceof ContainerPeer) {
                ((ContainerPeer)peer).beginLayout();
            }
            if (!isValid()) {
                doLayout();
            }
            for (int i = 0; i < component.size(); i++) {
                Component comp = component.get(i);
                if (   (comp instanceof Container)
                       && !(comp instanceof Window)
                       && (!comp.isValid() ||
                           descendUnconditionallyWhenValidating))
                {
                    ((Container)comp).validateTree();
                } else {
                    comp.validate();
                }
            }
            if (peer instanceof ContainerPeer) {
                ((ContainerPeer)peer).endLayout();
            }
        }
        super.validate();
    }

    /**
     * Recursively descends the container tree and invalidates all
     * contained components.
     */
    void invalidateTree() {
        synchronized (getTreeLock()) {
            for (int i = 0; i < component.size(); i++) {
                Component comp = component.get(i);
                if (comp instanceof Container) {
                    ((Container)comp).invalidateTree();
                }
                else {
                    comp.invalidateIfValid();
                }
            }
            invalidateIfValid();
        }
    }

    /**
     * Sets the font of this container.
     * <p>
     * This method changes layout-related information, and therefore,
     * invalidates the component hierarchy.
     *
     * @param f The font to become this container's font.
     * @see Component#getFont
     * @see #invalidate
     * @since JDK1.0
     */
    public void setFont(Font f) {
        boolean shouldinvalidate = false;

        Font oldfont = getFont();
        super.setFont(f);
        Font newfont = getFont();
        if (newfont != oldfont && (oldfont == null ||
                                   !oldfont.equals(newfont))) {
            invalidateTree();
        }
    }

    /**
     * Returns the preferred size of this container.  If the preferred size has
     * not been set explicitly by {@link Component#setPreferredSize(Dimension)}
     * and this {@code Container} has a {@code non-null} {@link LayoutManager},
     * then {@link LayoutManager#preferredLayoutSize(Container)}
     * is used to calculate the preferred size.
     *
     * <p>Note: some implementations may cache the value returned from the
     * {@code LayoutManager}.  Implementations that cache need not invoke
     * {@code preferredLayoutSize} on the {@code LayoutManager} every time
     * this method is invoked, rather the {@code LayoutManager} will only
     * be queried after the {@code Container} becomes invalid.
     *
     * @return    an instance of <code>Dimension that represents
     *                the preferred size of this container.
     * @see       #getMinimumSize
     * @see       #getMaximumSize
     * @see       #getLayout
     * @see       LayoutManager#preferredLayoutSize(Container)
     * @see       Component#getPreferredSize
     */
    public Dimension getPreferredSize() {
        return preferredSize();
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by <code>getPreferredSize().
     */
    @Deprecated
    public Dimension preferredSize() {
        /* Avoid grabbing the lock if a reasonable cached size value
         * is available.
         */
        Dimension dim = prefSize;
        if (dim == null || !(isPreferredSizeSet() || isValid())) {
            synchronized (getTreeLock()) {
                prefSize = (layoutMgr != null) ?
                    layoutMgr.preferredLayoutSize(this) :
                    super.preferredSize();
                dim = prefSize;
            }
        }
        if (dim != null){
            return new Dimension(dim);
        }
        else{
            return dim;
        }
    }

    /**
     * Returns the minimum size of this container.  If the minimum size has
     * not been set explicitly by {@link Component#setMinimumSize(Dimension)}
     * and this {@code Container} has a {@code non-null} {@link LayoutManager},
     * then {@link LayoutManager#minimumLayoutSize(Container)}
     * is used to calculate the minimum size.
     *
     * <p>Note: some implementations may cache the value returned from the
     * {@code LayoutManager}.  Implementations that cache need not invoke
     * {@code minimumLayoutSize} on the {@code LayoutManager} every time
     * this method is invoked, rather the {@code LayoutManager} will only
     * be queried after the {@code Container} becomes invalid.
     *
     * @return    an instance of <code>Dimension that represents
     *                the minimum size of this container.
     * @see       #getPreferredSize
     * @see       #getMaximumSize
     * @see       #getLayout
     * @see       LayoutManager#minimumLayoutSize(Container)
     * @see       Component#getMinimumSize
     * @since     JDK1.1
     */
    public Dimension getMinimumSize() {
        return minimumSize();
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by <code>getMinimumSize().
     */
    @Deprecated
    public Dimension minimumSize() {
        /* Avoid grabbing the lock if a reasonable cached size value
         * is available.
         */
        Dimension dim = minSize;
        if (dim == null || !(isMinimumSizeSet() || isValid())) {
            synchronized (getTreeLock()) {
                minSize = (layoutMgr != null) ?
                    layoutMgr.minimumLayoutSize(this) :
                    super.minimumSize();
                dim = minSize;
            }
        }
        if (dim != null){
            return new Dimension(dim);
        }
        else{
            return dim;
        }
    }

    /**
     * Returns the maximum size of this container.  If the maximum size has
     * not been set explicitly by {@link Component#setMaximumSize(Dimension)}
     * and the {@link LayoutManager} installed on this {@code Container}
     * is an instance of {@link LayoutManager2}, then
     * {@link LayoutManager2#maximumLayoutSize(Container)}
     * is used to calculate the maximum size.
     *
     * <p>Note: some implementations may cache the value returned from the
     * {@code LayoutManager2}.  Implementations that cache need not invoke
     * {@code maximumLayoutSize} on the {@code LayoutManager2} every time
     * this method is invoked, rather the {@code LayoutManager2} will only
     * be queried after the {@code Container} becomes invalid.
     *
     * @return    an instance of <code>Dimension that represents
     *                the maximum size of this container.
     * @see       #getPreferredSize
     * @see       #getMinimumSize
     * @see       #getLayout
     * @see       LayoutManager2#maximumLayoutSize(Container)
     * @see       Component#getMaximumSize
     */
    public Dimension getMaximumSize() {
        /* Avoid grabbing the lock if a reasonable cached size value
         * is available.
         */
        Dimension dim = maxSize;
        if (dim == null || !(isMaximumSizeSet() || isValid())) {
            synchronized (getTreeLock()) {
               if (layoutMgr instanceof LayoutManager2) {
                    LayoutManager2 lm = (LayoutManager2) layoutMgr;
                    maxSize = lm.maximumLayoutSize(this);
               } else {
                    maxSize = super.getMaximumSize();
               }
               dim = maxSize;
            }
        }
        if (dim != null){
            return new Dimension(dim);
        }
        else{
            return dim;
        }
    }

    /**
     * Returns the alignment along the x axis.  This specifies how
     * the component would like to be aligned relative to other
     * components.  The value should be a number between 0 and 1
     * where 0 represents alignment along the origin, 1 is aligned
     * the furthest away from the origin, 0.5 is centered, etc.
     */
    public float getAlignmentX() {
        float xAlign;
        if (layoutMgr instanceof LayoutManager2) {
            synchronized (getTreeLock()) {
                LayoutManager2 lm = (LayoutManager2) layoutMgr;
                xAlign = lm.getLayoutAlignmentX(this);
            }
        } else {
            xAlign = super.getAlignmentX();
        }
        return xAlign;
    }

    /**
     * Returns the alignment along the y axis.  This specifies how
     * the component would like to be aligned relative to other
     * components.  The value should be a number between 0 and 1
     * where 0 represents alignment along the origin, 1 is aligned
     * the furthest away from the origin, 0.5 is centered, etc.
     */
    public float getAlignmentY() {
        float yAlign;
        if (layoutMgr instanceof LayoutManager2) {
            synchronized (getTreeLock()) {
                LayoutManager2 lm = (LayoutManager2) layoutMgr;
                yAlign = lm.getLayoutAlignmentY(this);
            }
        } else {
            yAlign = super.getAlignmentY();
        }
        return yAlign;
    }

    /**
     * Paints the container. This forwards the paint to any lightweight
     * components that are children of this container. If this method is
     * reimplemented, super.paint(g) should be called so that lightweight
     * components are properly rendered. If a child component is entirely
     * clipped by the current clipping setting in g, paint() will not be
     * forwarded to that child.
     *
     * @param g the specified Graphics window
     * @see   Component#update(Graphics)
     */
    public void paint(Graphics g) {
        if (isShowing()) {
            synchronized (getObjectLock()) {
                if (printing) {
                    if (printingThreads.contains(Thread.currentThread())) {
                        return;
                    }
                }
            }

            // The container is showing on screen and
            // this paint() is not called from print().
            // Paint self and forward the paint to lightweight subcomponents.

            // super.paint(); -- Don't bother, since it's a NOP.

            GraphicsCallback.PaintCallback.getInstance().
                runComponents(getComponentsSync(), g, GraphicsCallback.LIGHTWEIGHTS);
        }
    }

    /**
     * Updates the container.  This forwards the update to any lightweight
     * components that are children of this container.  If this method is
     * reimplemented, super.update(g) should be called so that lightweight
     * components are properly rendered.  If a child component is entirely
     * clipped by the current clipping setting in g, update() will not be
     * forwarded to that child.
     *
     * @param g the specified Graphics window
     * @see   Component#update(Graphics)
     */
    public void update(Graphics g) {
        if (isShowing()) {
            if (! (peer instanceof LightweightPeer)) {
                g.clearRect(0, 0, width, height);
            }
            paint(g);
        }
    }

    /**
     * Prints the container. This forwards the print to any lightweight
     * components that are children of this container. If this method is
     * reimplemented, super.print(g) should be called so that lightweight
     * components are properly rendered. If a child component is entirely
     * clipped by the current clipping setting in g, print() will not be
     * forwarded to that child.
     *
     * @param g the specified Graphics window
     * @see   Component#update(Graphics)
     */
    public void print(Graphics g) {
        if (isShowing()) {
            Thread t = Thread.currentThread();
            try {
                synchronized (getObjectLock()) {
                    if (printingThreads == null) {
                        printingThreads = new HashSet<>();
                    }
                    printingThreads.add(t);
                    printing = true;
                }
                super.print(g);  // By default, Component.print() calls paint()
            } finally {
                synchronized (getObjectLock()) {
                    printingThreads.remove(t);
                    printing = !printingThreads.isEmpty();
                }
            }

            GraphicsCallback.PrintCallback.getInstance().
                runComponents(getComponentsSync(), g, GraphicsCallback.LIGHTWEIGHTS);
        }
    }

    /**
     * Paints each of the components in this container.
     * @param     g   the graphics context.
     * @see       Component#paint
     * @see       Component#paintAll
     */
    public void paintComponents(Graphics g) {
        if (isShowing()) {
            GraphicsCallback.PaintAllCallback.getInstance().
                runComponents(getComponentsSync(), g, GraphicsCallback.TWO_PASSES);
        }
    }

    /**
     * Simulates the peer callbacks into java.awt for printing of
     * lightweight Containers.
     * @param     g   the graphics context to use for printing.
     * @see       Component#printAll
     * @see       #printComponents
     */
    void lightweightPaint(Graphics g) {
        super.lightweightPaint(g);
        paintHeavyweightComponents(g);
    }

    /**
     * Prints all the heavyweight subcomponents.
     */
    void paintHeavyweightComponents(Graphics g) {
        if (isShowing()) {
            GraphicsCallback.PaintHeavyweightComponentsCallback.getInstance().
                runComponents(getComponentsSync(), g,
                              GraphicsCallback.LIGHTWEIGHTS | GraphicsCallback.HEAVYWEIGHTS);
        }
    }

    /**
     * Prints each of the components in this container.
     * @param     g   the graphics context.
     * @see       Component#print
     * @see       Component#printAll
     */
    public void printComponents(Graphics g) {
        if (isShowing()) {
            GraphicsCallback.PrintAllCallback.getInstance().
                runComponents(getComponentsSync(), g, GraphicsCallback.TWO_PASSES);
        }
    }

    /**
     * Simulates the peer callbacks into java.awt for printing of
     * lightweight Containers.
     * @param     g   the graphics context to use for printing.
     * @see       Component#printAll
     * @see       #printComponents
     */
    void lightweightPrint(Graphics g) {
        super.lightweightPrint(g);
        printHeavyweightComponents(g);
    }

    /**
     * Prints all the heavyweight subcomponents.
     */
    void printHeavyweightComponents(Graphics g) {
        if (isShowing()) {
            GraphicsCallback.PrintHeavyweightComponentsCallback.getInstance().
                runComponents(getComponentsSync(), g,
                              GraphicsCallback.LIGHTWEIGHTS | GraphicsCallback.HEAVYWEIGHTS);
        }
    }

    /**
     * Adds the specified container listener to receive container events
     * from this container.
     * If l is null, no exception is thrown and no action is performed.
     * <p>Refer to  for details on AWT's threading model.
     *
     * @param    l the container listener
     *
     * @see #removeContainerListener
     * @see #getContainerListeners
     */
    public synchronized void addContainerListener(ContainerListener l) {
        if (l == null) {
            return;
        }
        containerListener = AWTEventMulticaster.add(containerListener, l);
        newEventsOnly = true;
    }

    /**
     * Removes the specified container listener so it no longer receives
     * container events from this container.
     * If l is null, no exception is thrown and no action is performed.
     * <p>Refer to  for details on AWT's threading model.
     *
     * @param   l the container listener
     *
     * @see #addContainerListener
     * @see #getContainerListeners
     */
    public synchronized void removeContainerListener(ContainerListener l) {
        if (l == null) {
            return;
        }
        containerListener = AWTEventMulticaster.remove(containerListener, l);
    }

    /**
     * Returns an array of all the container listeners
     * registered on this container.
     *
     * @return all of this container's <code>ContainerListeners
     *         or an empty array if no container
     *         listeners are currently registered
     *
     * @see #addContainerListener
     * @see #removeContainerListener
     * @since 1.4
     */
    public synchronized ContainerListener[] getContainerListeners() {
        return getListeners(ContainerListener.class);
    }

    /**
     * Returns an array of all the objects currently registered
     * as <code>FooListeners
     * upon this <code>Container.
     * <code>FooListeners are registered using the
     * <code>addFooListener method.
     *
     * <p>
     * You can specify the <code>listenerType argument
     * with a class literal, such as
     * <code>FooListener.class.
     * For example, you can query a
     * <code>Container c
     * for its container listeners with the following code:
     *
     * <pre>ContainerListener[] cls = (ContainerListener[])(c.getListeners(ContainerListener.class));