https://openjdk.java.net/ 
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 * 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,
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 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */
package java.awt;

import java.awt.peer.CheckboxPeer;
import java.awt.event.*;
import java.util.EventListener;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import javax.accessibility.*;



A check box is a graphical component that can be in either an
"on" (true) or "off" (false) state.
Clicking on a check box changes its state from
"on" to "off," or from "off" to "on."


The following code example creates a set of check boxes in
a grid layout:

setLayout(new GridLayout(3, 1));
add(new Checkbox("one", null, true));
add(new Checkbox("two"));
add(new Checkbox("three"));




This image depicts the check boxes and grid layout
created by this code example:





The button labeled one is in the "on" state, and the
other two are in the "off" state. In this example, which uses the
GridLayout class, the states of the three check
boxes are set independently.


Alternatively, several check boxes can be grouped together under
the control of a single object, using the
CheckboxGroup class.
In a check box group, at most one button can be in the "on"
state at any given time. Clicking on a check box to turn it on
forces any other check box in the same group that is on
into the "off" state.

Author:     Sami Shaio
See Also:
Since:      JDK1.0
/**
 * A check box is a graphical component that can be in either an
 * "on" (<code>true</code>) or "off" (<code>false</code>) state.
 * Clicking on a check box changes its state from
 * "on" to "off," or from "off" to "on."
 * <p>
 * The following code example creates a set of check boxes in
 * a grid layout:
 *
 * <hr><blockquote><pre>
 * setLayout(new GridLayout(3, 1));
 * add(new Checkbox("one", null, true));
 * add(new Checkbox("two"));
 * add(new Checkbox("three"));
 * </pre></blockquote><hr>
 * <p>
 * This image depicts the check boxes and grid layout
 * created by this code example:
 * <p>
 * <img src="doc-files/Checkbox-1.gif" alt="The following context describes the graphic."
 * style="float:center; margin: 7px 10px;">
 * <p>
 * The button labeled <code>one</code> is in the "on" state, and the
 * other two are in the "off" state. In this example, which uses the
 * <code>GridLayout</code> class, the states of the three check
 * boxes are set independently.
 * <p>
 * Alternatively, several check boxes can be grouped together under
 * the control of a single object, using the
 * <code>CheckboxGroup</code> class.
 * In a check box group, at most one button can be in the "on"
 * state at any given time. Clicking on a check box to turn it on
 * forces any other check box in the same group that is on
 * into the "off" state.
 *
 * @author      Sami Shaio
 * @see         java.awt.GridLayout
 * @see         java.awt.CheckboxGroup
 * @since       JDK1.0
 */
public class Checkbox extends Component implements ItemSelectable, Accessible {

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

    
The label of the Checkbox.
This field can be null.

See Also:
@serial
/**
     * The label of the Checkbox.
     * This field can be null.
     * @serial
     * @see #getLabel()
     * @see #setLabel(String)
     */
    String label;

    
The state of the Checkbox.

See Also:
@serial
/**
     * The state of the <code>Checkbox</code>.
     * @serial
     * @see #getState()
     * @see #setState(boolean)
     */
    boolean state;

    
The check box group.
This field can be null indicating that the checkbox
is not a group checkbox.

See Also:
@serial
/**
     * The check box group.
         * This field can be null indicating that the checkbox
         * is not a group checkbox.
         * @serial
     * @see #getCheckboxGroup()
     * @see #setCheckboxGroup(CheckboxGroup)
     */
    CheckboxGroup group;

    transient ItemListener itemListener;

    private static final String base = "checkbox";
    private static int nameCounter = 0;

    /*
     * JDK 1.1 serialVersionUID
     */
    private static final long serialVersionUID = 7270714317450821763L;

    
Helper function for setState and CheckboxGroup.setSelectedCheckbox
Should remain package-private.

/**
     * Helper function for setState and CheckboxGroup.setSelectedCheckbox
     * Should remain package-private.
     */
    void setStateInternal(boolean state) {
        this.state = state;
        CheckboxPeer peer = (CheckboxPeer)this.peer;
        if (peer != null) {
            peer.setState(state);
        }
    }

    
Creates a check box with an empty string for its label.
The state of this check box is set to "off," and it is not
part of any check box group.

Throws:
  • HeadlessException – if GraphicsEnvironment.isHeadless()
returns true
See Also:
/**
     * Creates a check box with an empty string for its label.
     * The state of this check box is set to "off," and it is not
     * part of any check box group.
     * @exception HeadlessException if GraphicsEnvironment.isHeadless()
     * returns true
     * @see java.awt.GraphicsEnvironment#isHeadless
     */
    public Checkbox() throws HeadlessException {
        this("", false, null);
    }

    
Creates a check box with the specified label.  The state
of this check box is set to "off," and it is not part of
any check box group.

Params:
  • label –   a string label for this check box,
                       or null for no label.
Throws:
See Also:
/**
     * Creates a check box with the specified label.  The state
     * of this check box is set to "off," and it is not part of
     * any check box group.
     *
     * @param     label   a string label for this check box,
     *                        or <code>null</code> for no label.
     * @exception HeadlessException if
     *      <code>GraphicsEnvironment.isHeadless</code>
     *      returns <code>true</code>
     * @see java.awt.GraphicsEnvironment#isHeadless
     */
    public Checkbox(String label) throws HeadlessException {
        this(label, false, null);
    }

    
Creates a check box with the specified label
and sets the specified state.
This check box is not part of any check box group.

Params:
  • label –   a string label for this check box,
                       or null for no label
  • state –    the initial state of this check box
Throws:
See Also:
/**
     * Creates a check box with the specified label
     * and sets the specified state.
     * This check box is not part of any check box group.
     *
     * @param     label   a string label for this check box,
     *                        or <code>null</code> for no label
     * @param     state    the initial state of this check box
     * @exception HeadlessException if
     *     <code>GraphicsEnvironment.isHeadless</code>
     *     returns <code>true</code>
     * @see java.awt.GraphicsEnvironment#isHeadless
     */
    public Checkbox(String label, boolean state) throws HeadlessException {
        this(label, state, null);
    }

    
Constructs a Checkbox with the specified label, set to the
specified state, and in the specified check box group.

Params:
  • label –   a string label for this check box,
                       or null for no label.
  • state –   the initial state of this check box.
  • group –   a check box group for this check box,
                          or null for no group.
Throws:
See Also:
Since:    JDK1.1
/**
     * Constructs a Checkbox with the specified label, set to the
     * specified state, and in the specified check box group.
     *
     * @param     label   a string label for this check box,
     *                        or <code>null</code> for no label.
     * @param     state   the initial state of this check box.
     * @param     group   a check box group for this check box,
     *                           or <code>null</code> for no group.
     * @exception HeadlessException if
     *     <code>GraphicsEnvironment.isHeadless</code>
     *     returns <code>true</code>
     * @see java.awt.GraphicsEnvironment#isHeadless
     * @since     JDK1.1
     */
    public Checkbox(String label, boolean state, CheckboxGroup group)
        throws HeadlessException {
        GraphicsEnvironment.checkHeadless();
        this.label = label;
        this.state = state;
        this.group = group;
        if (state && (group != null)) {
            group.setSelectedCheckbox(this);
        }
    }

    
Creates a check box with the specified label, in the specified
check box group, and set to the specified state.

Params:
  • label –   a string label for this check box,
                       or null for no label.
  • group –   a check box group for this check box,
                          or null for no group.
  • state –   the initial state of this check box.
Throws:
See Also:
Since:    JDK1.1
/**
     * Creates a check box with the specified label, in the specified
     * check box group, and set to the specified state.
     *
     * @param     label   a string label for this check box,
     *                        or <code>null</code> for no label.
     * @param     group   a check box group for this check box,
     *                           or <code>null</code> for no group.
     * @param     state   the initial state of this check box.
     * @exception HeadlessException if
     *    <code>GraphicsEnvironment.isHeadless</code>
     *    returns <code>true</code>
     * @see java.awt.GraphicsEnvironment#isHeadless
     * @since     JDK1.1
     */
    public Checkbox(String label, CheckboxGroup group, boolean state)
        throws HeadlessException {
        this(label, state, group);
    }

    
Constructs a name for this component.  Called by
getName when the name is null.

Returns:a name for this component
/**
     * Constructs a name for this component.  Called by
     * <code>getName</code> when the name is <code>null</code>.
     *
     * @return a name for this component
     */
    String constructComponentName() {
        synchronized (Checkbox.class) {
            return base + nameCounter++;
        }
    }

    
Creates the peer of the Checkbox. The peer allows you to change the
look of the Checkbox without changing its functionality.

See Also:
/**
     * Creates the peer of the Checkbox. The peer allows you to change the
     * look of the Checkbox without changing its functionality.
     *
     * @see     java.awt.Toolkit#createCheckbox(java.awt.Checkbox)
     * @see     java.awt.Component#getToolkit()
     */
    public void addNotify() {
        synchronized (getTreeLock()) {
            if (peer == null)
                peer = getToolkit().createCheckbox(this);
            super.addNotify();
        }
    }

    
Gets the label of this check box.

See Also:
Returns:  the label of this check box, or null
                 if this check box has no label.
/**
     * Gets the label of this check box.
     *
     * @return   the label of this check box, or <code>null</code>
     *                  if this check box has no label.
     * @see      #setLabel(String)
     */
    public String getLabel() {
        return label;
    }

    
Sets this check box's label to be the string argument.

Params:
  • label –   a string to set as the new label, or
                       null for no label.
See Also:
/**
     * Sets this check box's label to be the string argument.
     *
     * @param    label   a string to set as the new label, or
     *                        <code>null</code> for no label.
     * @see      #getLabel
     */
    public void setLabel(String label) {
        boolean testvalid = false;

        synchronized (this) {
            if (label != this.label && (this.label == null ||
                                        !this.label.equals(label))) {
                this.label = label;
                CheckboxPeer peer = (CheckboxPeer)this.peer;
                if (peer != null) {
                    peer.setLabel(label);
                }
                testvalid = true;
            }
        }

        // This could change the preferred size of the Component.
        if (testvalid) {
            invalidateIfValid();
        }
    }

    
Determines whether this check box is in the "on" or "off" state.
The boolean value true indicates the "on" state,
and false indicates the "off" state.

See Also:
Returns:   the state of this check box, as a boolean value
/**
     * Determines whether this check box is in the "on" or "off" state.
     * The boolean value <code>true</code> indicates the "on" state,
     * and <code>false</code> indicates the "off" state.
     *
     * @return    the state of this check box, as a boolean value
     * @see       #setState
     */
    public boolean getState() {
        return state;
    }

    
Sets the state of this check box to the specified state.
The boolean value true indicates the "on" state,
and false indicates the "off" state.

Note that this method should be primarily used to
initialize the state of the checkbox.  Programmatically
setting the state of the checkbox will not trigger
an ItemEvent.  The only way to trigger an
ItemEvent is by user interaction.

Params:
  • state –   the boolean state of the check box
See Also:
/**
     * Sets the state of this check box to the specified state.
     * The boolean value <code>true</code> indicates the "on" state,
     * and <code>false</code> indicates the "off" state.
     *
     * <p>Note that this method should be primarily used to
     * initialize the state of the checkbox.  Programmatically
     * setting the state of the checkbox will <i>not</i> trigger
     * an <code>ItemEvent</code>.  The only way to trigger an
     * <code>ItemEvent</code> is by user interaction.
     *
     * @param     state   the boolean state of the check box
     * @see       #getState
     */
    public void setState(boolean state) {
        /* Cannot hold check box lock when calling group.setSelectedCheckbox. */
        CheckboxGroup group = this.group;
        if (group != null) {
            if (state) {
                group.setSelectedCheckbox(this);
            } else if (group.getSelectedCheckbox() == this) {
                state = true;
            }
        }
        setStateInternal(state);
    }

    
Returns an array (length 1) containing the checkbox
label or null if the checkbox is not selected.

See Also:
  • ItemSelectable
/**
     * Returns an array (length 1) containing the checkbox
     * label or null if the checkbox is not selected.
     * @see ItemSelectable
     */
    public Object[] getSelectedObjects() {
        if (state) {
            Object[] items = new Object[1];
            items[0] = label;
            return items;
        }
        return null;
    }

    
Determines this check box's group.

See Also:
Returns:    this check box's group, or null
              if the check box is not part of a check box group.
/**
     * Determines this check box's group.
     * @return     this check box's group, or <code>null</code>
     *               if the check box is not part of a check box group.
     * @see        #setCheckboxGroup(CheckboxGroup)
     */
    public CheckboxGroup getCheckboxGroup() {
        return group;
    }

    
Sets this check box's group to the specified check box group.
If this check box is already in a different check box group,
it is first taken out of that group.


If the state of this check box is true and the new
group already has a check box selected, this check box's state
is changed to false.  If the state of this check
box is true and the new group has no check box
selected, this check box becomes the selected checkbox for
the new group and its state is true.

Params:
  • g –   the new check box group, or null
               to remove this check box from any check box group
See Also:
/**
     * Sets this check box's group to the specified check box group.
     * If this check box is already in a different check box group,
     * it is first taken out of that group.
     * <p>
     * If the state of this check box is <code>true</code> and the new
     * group already has a check box selected, this check box's state
     * is changed to <code>false</code>.  If the state of this check
     * box is <code>true</code> and the new group has no check box
     * selected, this check box becomes the selected checkbox for
     * the new group and its state is <code>true</code>.
     *
     * @param     g   the new check box group, or <code>null</code>
     *                to remove this check box from any check box group
     * @see       #getCheckboxGroup
     */
    public void setCheckboxGroup(CheckboxGroup g) {
        CheckboxGroup oldGroup;
        boolean oldState;

        /* Do nothing if this check box has already belonged
         * to the check box group g.
         */
        if (this.group == g) {
            return;
        }

        synchronized (this) {
            oldGroup = this.group;
            oldState = getState();

            this.group = g;
            CheckboxPeer peer = (CheckboxPeer)this.peer;
            if (peer != null) {
                peer.setCheckboxGroup(g);
            }
            if (this.group != null && getState()) {
                if (this.group.getSelectedCheckbox() != null) {
                    setState(false);
                } else {
                    this.group.setSelectedCheckbox(this);
                }
            }
        }

        /* Locking check box below could cause deadlock with
         * CheckboxGroup's setSelectedCheckbox method.
         *
         * Fix for 4726853 by kdm@sparc.spb.su
         * Here we should check if this check box was selected
         * in the previous group and set selected check box to
         * null for that group if so.
         */
        if (oldGroup != null && oldState) {
            oldGroup.setSelectedCheckbox(null);
        }
    }

    
Adds the specified item listener to receive item events from
this check box.  Item events are sent to listeners in response
to user input, but not in response to calls to setState().
If l is null, no exception is thrown and no action is performed.

Refer to AWT Threading Issues for details on AWT's threading model.

Params:
  • l –    the item listener
See Also:
Since:        JDK1.1
/**
     * Adds the specified item listener to receive item events from
     * this check box.  Item events are sent to listeners in response
     * to user input, but not in response to calls to setState().
     * If l is null, no exception is thrown and no action is performed.
     * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
     * >AWT Threading Issues</a> for details on AWT's threading model.
     *
     * @param         l    the item listener
     * @see           #removeItemListener
     * @see           #getItemListeners
     * @see           #setState
     * @see           java.awt.event.ItemEvent
     * @see           java.awt.event.ItemListener
     * @since         JDK1.1
     */
    public synchronized void addItemListener(ItemListener l) {
        if (l == null) {
            return;
        }
        itemListener = AWTEventMulticaster.add(itemListener, l);
        newEventsOnly = true;
    }

    
Removes the specified item listener so that the item listener
no longer receives item events from this check box.
If l is null, no exception is thrown and no action is performed.

Refer to AWT Threading Issues for details on AWT's threading model.

Params:
  • l –    the item listener
See Also:
Since:        JDK1.1
/**
     * Removes the specified item listener so that the item listener
     * no longer receives item events from this check box.
     * If l is null, no exception is thrown and no action is performed.
     * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
     * >AWT Threading Issues</a> for details on AWT's threading model.
     *
     * @param         l    the item listener
     * @see           #addItemListener
     * @see           #getItemListeners
     * @see           java.awt.event.ItemEvent
     * @see           java.awt.event.ItemListener
     * @since         JDK1.1
     */
    public synchronized void removeItemListener(ItemListener l) {
        if (l == null) {
            return;
        }
        itemListener = AWTEventMulticaster.remove(itemListener, l);
    }

    
Returns an array of all the item listeners
registered on this checkbox.

See Also:
Returns:all of this checkbox's ItemListeners
        or an empty array if no item
        listeners are currently registered
Since:1.4
/**
     * Returns an array of all the item listeners
     * registered on this checkbox.
     *
     * @return all of this checkbox's <code>ItemListener</code>s
     *         or an empty array if no item
     *         listeners are currently registered
     *
     * @see           #addItemListener
     * @see           #removeItemListener
     * @see           java.awt.event.ItemEvent
     * @see           java.awt.event.ItemListener
     * @since 1.4
     */
    public synchronized ItemListener[] getItemListeners() {
        return getListeners(ItemListener.class);
    }

    
Returns an array of all the objects currently registered
as FooListeners
upon this Checkbox.
FooListeners are registered using the
addFooListener method.


You can specify the listenerType argument
with a class literal, such as
FooListener.class.
For example, you can query a
Checkbox c
for its item listeners with the following code:

ItemListener[] ils = (ItemListener[])(c.getListeners(ItemListener.class));

If no such listeners exist, this method returns an empty array.

Params:
  • listenerType – the type of listeners requested; this parameter
         should specify an interface that descends from
         java.util.EventListener
Throws:
  • ClassCastException – if listenerType
         doesn't specify a class or interface that implements
         java.util.EventListener
See Also:
Returns:an array of all objects registered as
         FooListeners on this checkbox,
         or an empty array if no such
         listeners have been added
Since:1.3
/**
     * Returns an array of all the objects currently registered
     * as <code><em>Foo</em>Listener</code>s
     * upon this <code>Checkbox</code>.
     * <code><em>Foo</em>Listener</code>s are registered using the
     * <code>add<em>Foo</em>Listener</code> method.
     *
     * <p>
     * You can specify the <code>listenerType</code> argument
     * with a class literal, such as
     * <code><em>Foo</em>Listener.class</code>.
     * For example, you can query a
     * <code>Checkbox</code> <code>c</code>
     * for its item listeners with the following code:
     *
     * <pre>ItemListener[] ils = (ItemListener[])(c.getListeners(ItemListener.class));</pre>
     *
     * If no such listeners exist, this method returns an empty array.
     *
     * @param listenerType the type of listeners requested; this parameter
     *          should specify an interface that descends from
     *          <code>java.util.EventListener</code>
     * @return an array of all objects registered as
     *          <code><em>Foo</em>Listener</code>s on this checkbox,
     *          or an empty array if no such
     *          listeners have been added
     * @exception ClassCastException if <code>listenerType</code>
     *          doesn't specify a class or interface that implements
     *          <code>java.util.EventListener</code>
     *
     * @see #getItemListeners
     * @since 1.3
     */
    public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
        EventListener l = null;
        if  (listenerType == ItemListener.class) {
            l = itemListener;
        } else {
            return super.getListeners(listenerType);
        }
        return AWTEventMulticaster.getListeners(l, listenerType);
    }

    // REMIND: remove when filtering is done at lower level
    boolean eventEnabled(AWTEvent e) {
        if (e.id == ItemEvent.ITEM_STATE_CHANGED) {
            if ((eventMask & AWTEvent.ITEM_EVENT_MASK) != 0 ||
                itemListener != null) {
                return true;
            }
            return false;
        }
        return super.eventEnabled(e);
    }

    
Processes events on this check box.
If the event is an instance of ItemEvent,
this method invokes the processItemEvent method.
Otherwise, it calls its superclass's processEvent method.

Note that if the event parameter is null
the behavior is unspecified and may result in an
exception.

Params:
  • e – the event
See Also:
Since:        JDK1.1
/**
     * Processes events on this check box.
     * If the event is an instance of <code>ItemEvent</code>,
     * this method invokes the <code>processItemEvent</code> method.
     * Otherwise, it calls its superclass's <code>processEvent</code> method.
     * <p>Note that if the event parameter is <code>null</code>
     * the behavior is unspecified and may result in an
     * exception.
     *
     * @param         e the event
     * @see           java.awt.event.ItemEvent
     * @see           #processItemEvent
     * @since         JDK1.1
     */
    protected void processEvent(AWTEvent e) {
        if (e instanceof ItemEvent) {
            processItemEvent((ItemEvent)e);
            return;
        }
        super.processEvent(e);
    }

    
Processes item events occurring on this check box by
dispatching them to any registered
ItemListener objects.


This method is not called unless item events are
enabled for this component. Item events are enabled
when one of the following occurs:

    

  • An ItemListener object is registered
via addItemListener.

  • Item events are enabled via enableEvents.



Note that if the event parameter is null
the behavior is unspecified and may result in an
exception.

Params:
  • e – the item event
See Also:
Since:      JDK1.1
/**
     * Processes item events occurring on this check box by
     * dispatching them to any registered
     * <code>ItemListener</code> objects.
     * <p>
     * This method is not called unless item events are
     * enabled for this component. Item events are enabled
     * when one of the following occurs:
     * <ul>
     * <li>An <code>ItemListener</code> object is registered
     * via <code>addItemListener</code>.
     * <li>Item events are enabled via <code>enableEvents</code>.
     * </ul>
     * <p>Note that if the event parameter is <code>null</code>
     * the behavior is unspecified and may result in an
     * exception.
     *
     * @param       e the item event
     * @see         java.awt.event.ItemEvent
     * @see         java.awt.event.ItemListener
     * @see         #addItemListener
     * @see         java.awt.Component#enableEvents
     * @since       JDK1.1
     */
    protected void processItemEvent(ItemEvent e) {
        ItemListener listener = itemListener;
        if (listener != null) {
            listener.itemStateChanged(e);
        }
    }

    
Returns a string representing the state of this Checkbox.
This method is intended to be used only for debugging purposes, and the
content and format of the returned string may vary between
implementations. The returned string may be empty but may not be
null.

Returns:   the parameter string of this check box
/**
     * Returns a string representing the state of this <code>Checkbox</code>.
     * This method is intended to be used only for debugging purposes, and the
     * content and format of the returned string may vary between
     * implementations. The returned string may be empty but may not be
     * <code>null</code>.
     *
     * @return    the parameter string of this check box
     */
    protected String paramString() {
        String str = super.paramString();
        String label = this.label;
        if (label != null) {
            str += ",label=" + label;
        }
        return str + ",state=" + state;
    }


    /* Serialization support.
     */

    /*
     * Serialized data version
     * @serial
     */
    private int checkboxSerializedDataVersion = 1;

    
Writes default serializable fields to stream.  Writes
a list of serializable ItemListeners
as optional data.  The non-serializable
ItemListeners are detected and
no attempt is made to serialize them.

Params:
  • s – the ObjectOutputStream to write
See Also:
@serialDatanull terminated sequence of 0
  or more pairs; the pair consists of a String
  and an Object; the String indicates
  the type of object and is one of the following:
  itemListenerK indicating an
    ItemListener object
/**
     * Writes default serializable fields to stream.  Writes
     * a list of serializable <code>ItemListeners</code>
     * as optional data.  The non-serializable
     * <code>ItemListeners</code> are detected and
     * no attempt is made to serialize them.
     *
     * @param s the <code>ObjectOutputStream</code> to write
     * @serialData <code>null</code> terminated sequence of 0
     *   or more pairs; the pair consists of a <code>String</code>
     *   and an <code>Object</code>; the <code>String</code> indicates
     *   the type of object and is one of the following:
     *   <code>itemListenerK</code> indicating an
     *     <code>ItemListener</code> object
     *
     * @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
     * @see java.awt.Component#itemListenerK
     * @see #readObject(ObjectInputStream)
     */
    private void writeObject(ObjectOutputStream s)
      throws java.io.IOException
    {
      s.defaultWriteObject();

      AWTEventMulticaster.save(s, itemListenerK, itemListener);
      s.writeObject(null);
    }

    
Reads the ObjectInputStream and if it
isn't null adds a listener to receive
item events fired by the Checkbox.
Unrecognized keys or values will be ignored.

Params:
  • s – the ObjectInputStream to read
Throws:
See Also:
@serial
/**
     * Reads the <code>ObjectInputStream</code> and if it
     * isn't <code>null</code> adds a listener to receive
     * item events fired by the <code>Checkbox</code>.
     * Unrecognized keys or values will be ignored.
     *
     * @param s the <code>ObjectInputStream</code> to read
     * @exception HeadlessException if
     *   <code>GraphicsEnvironment.isHeadless</code> returns
     *   <code>true</code>
     * @serial
     * @see #removeItemListener(ItemListener)
     * @see #addItemListener(ItemListener)
     * @see java.awt.GraphicsEnvironment#isHeadless
     * @see #writeObject(ObjectOutputStream)
     */
    private void readObject(ObjectInputStream s)
      throws ClassNotFoundException, IOException, HeadlessException
    {
      GraphicsEnvironment.checkHeadless();
      s.defaultReadObject();

      Object keyOrNull;
      while(null != (keyOrNull = s.readObject())) {
        String key = ((String)keyOrNull).intern();

        if (itemListenerK == key)
          addItemListener((ItemListener)(s.readObject()));

        else // skip value for unrecognized key
          s.readObject();
      }
    }

    
Initialize JNI field and method ids

/**
     * Initialize JNI field and method ids
     */
    private static native void initIDs();


/////////////////
// Accessibility support
////////////////


    
Gets the AccessibleContext associated with this Checkbox.
For checkboxes, the AccessibleContext takes the form of an
AccessibleAWTCheckbox.
A new AccessibleAWTCheckbox is created if necessary.

Returns:an AccessibleAWTCheckbox that serves as the
        AccessibleContext of this Checkbox
Since:1.3
/**
     * Gets the AccessibleContext associated with this Checkbox.
     * For checkboxes, the AccessibleContext takes the form of an
     * AccessibleAWTCheckbox.
     * A new AccessibleAWTCheckbox is created if necessary.
     *
     * @return an AccessibleAWTCheckbox that serves as the
     *         AccessibleContext of this Checkbox
     * @since 1.3
     */
    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleAWTCheckbox();
        }
        return accessibleContext;
    }

    
This class implements accessibility support for the
Checkbox class.  It provides an implementation of the
Java Accessibility API appropriate to checkbox user-interface elements.

Since:1.3
/**
     * This class implements accessibility support for the
     * <code>Checkbox</code> class.  It provides an implementation of the
     * Java Accessibility API appropriate to checkbox user-interface elements.
     * @since 1.3
     */
    protected class AccessibleAWTCheckbox extends AccessibleAWTComponent
        implements ItemListener, AccessibleAction, AccessibleValue
    {
        /*
         * JDK 1.3 serialVersionUID
         */
        private static final long serialVersionUID = 7881579233144754107L;

        public AccessibleAWTCheckbox() {
            super();
            Checkbox.this.addItemListener(this);
        }

        
Fire accessible property change events when the state of the
toggle button changes.

/**
         * Fire accessible property change events when the state of the
         * toggle button changes.
         */
        public void itemStateChanged(ItemEvent e) {
            Checkbox cb = (Checkbox) e.getSource();
            if (Checkbox.this.accessibleContext != null) {
                if (cb.getState()) {
                    Checkbox.this.accessibleContext.firePropertyChange(
                            AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                            null, AccessibleState.CHECKED);
                } else {
                    Checkbox.this.accessibleContext.firePropertyChange(
                            AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                            AccessibleState.CHECKED, null);
                }
            }
        }

        
Get the AccessibleAction associated with this object.  In the
implementation of the Java Accessibility API for this class,
return this object, which is responsible for implementing the
AccessibleAction interface on behalf of itself.

Returns:this object
/**
         * Get the AccessibleAction associated with this object.  In the
         * implementation of the Java Accessibility API for this class,
         * return this object, which is responsible for implementing the
         * AccessibleAction interface on behalf of itself.
         *
         * @return this object
         */
        public AccessibleAction getAccessibleAction() {
            return this;
        }

        
Get the AccessibleValue associated with this object.  In the
implementation of the Java Accessibility API for this class,
return this object, which is responsible for implementing the
AccessibleValue interface on behalf of itself.

Returns:this object
/**
         * Get the AccessibleValue associated with this object.  In the
         * implementation of the Java Accessibility API for this class,
         * return this object, which is responsible for implementing the
         * AccessibleValue interface on behalf of itself.
         *
         * @return this object
         */
        public AccessibleValue getAccessibleValue() {
            return this;
        }

        
Returns the number of Actions available in this object.
If there is more than one, the first one is the "default"
action.

Returns:the number of Actions in this object
/**
         * Returns the number of Actions available in this object.
         * If there is more than one, the first one is the "default"
         * action.
         *
         * @return the number of Actions in this object
         */
        public int getAccessibleActionCount() {
            return 0;  //  To be fully implemented in a future release
        }

        
Return a description of the specified action of the object.

Params:
  • i – zero-based index of the actions
/**
         * Return a description of the specified action of the object.
         *
         * @param i zero-based index of the actions
         */
        public String getAccessibleActionDescription(int i) {
            return null;  //  To be fully implemented in a future release
        }

        
Perform the specified Action on the object

Params:
  • i – zero-based index of actions
Returns:true if the the action was performed; else false.
/**
         * Perform the specified Action on the object
         *
         * @param i zero-based index of actions
         * @return true if the the action was performed; else false.
         */
        public boolean doAccessibleAction(int i) {
            return false;    //  To be fully implemented in a future release
        }

        
Get the value of this object as a Number.  If the value has not been
set, the return value will be null.

See Also:
Returns:value of the object
/**
         * Get the value of this object as a Number.  If the value has not been
         * set, the return value will be null.
         *
         * @return value of the object
         * @see #setCurrentAccessibleValue
         */
        public Number getCurrentAccessibleValue() {
            return null;  //  To be fully implemented in a future release
        }

        
Set the value of this object as a Number.

See Also:
Returns:True if the value was set; else False
/**
         * Set the value of this object as a Number.
         *
         * @return True if the value was set; else False
         * @see #getCurrentAccessibleValue
         */
        public boolean setCurrentAccessibleValue(Number n) {
            return false;  //  To be fully implemented in a future release
        }

        
Get the minimum value of this object as a Number.

See Also:
Returns:Minimum value of the object; null if this object does not
have a minimum value
/**
         * Get the minimum value of this object as a Number.
         *
         * @return Minimum value of the object; null if this object does not
         * have a minimum value
         * @see #getMaximumAccessibleValue
         */
        public Number getMinimumAccessibleValue() {
            return null;  //  To be fully implemented in a future release
        }

        
Get the maximum value of this object as a Number.

See Also:
Returns:Maximum value of the object; null if this object does not
have a maximum value
/**
         * Get the maximum value of this object as a Number.
         *
         * @return Maximum value of the object; null if this object does not
         * have a maximum value
         * @see #getMinimumAccessibleValue
         */
        public Number getMaximumAccessibleValue() {
            return null;  //  To be fully implemented in a future release
        }

        
Get the role of this object.

See Also:
Returns:an instance of AccessibleRole describing the role of
the object
/**
         * Get the role of this object.
         *
         * @return an instance of AccessibleRole describing the role of
         * the object
         * @see AccessibleRole
         */
        public AccessibleRole getAccessibleRole() {
            return AccessibleRole.CHECK_BOX;
        }

        
Get the state set of this object.

See Also:
Returns:an instance of AccessibleState containing the current state
of the object
/**
         * Get the state set of this object.
         *
         * @return an instance of AccessibleState containing the current state
         * of the object
         * @see AccessibleState
         */
        public AccessibleStateSet getAccessibleStateSet() {
            AccessibleStateSet states = super.getAccessibleStateSet();
            if (getState()) {
                states.add(AccessibleState.CHECKED);
            }
            return states;
        }


    } // inner class AccessibleAWTCheckbox

}