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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,
	* 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.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" (<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.
	* @serial
	* @see #getLabel()
	* @see #setLabel(String)
	*/
	String label;

	/**
	* 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.
	* @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.
	*/
	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.
	* @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.
	*
	* @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.
	*
	* @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.
	*
	* @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.
	*
	* @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
	* <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 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.
	*
	* @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.
	*
	* @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 <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 <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 ItemSelectable
	*/
	public Object[] getSelectedObjects() {
	if (state) {
	Object[] items = new Object[1];
	items[0] = label;
	return items;
	}
	return null;
	}

	/**
	* 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.
	* <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.
	* <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.
	* <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.
	*
	* @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 <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 <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
	* <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 <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 <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 <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
	*/
	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.
	*
	* @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
	* <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.
	*/
	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.
	*
	* @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.
	*
	* @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.
	*
	* @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.
	*
	* @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
	*
	* @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.
	*
	* @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.
	*
	* @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.
	*
	* @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.
	*
	* @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.
	*
	* @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.
	*
	* @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

	}

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