/*
* @(#)Checkbox.java 1.59 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program 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.
*
* This program 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 at /legal/license.txt).
*
* 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 Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package java.awt;
import sun.awt.peer.CheckboxPeer;
import sun.awt.PeerBasedToolkit;
import java.awt.event.*;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import java.util.EventListener;
import java.awt.AWTEventMulticaster;
/**
* 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:
* <p>
* <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="images-awt/Checkbox-1.gif"
* ALIGN=center HSPACE=10 VSPACE=7>
* <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.
*
* @version 1.51 08/19/02
* @author Sami Shaio
* @see java.awt.GridLayout
* @see java.awt.CheckboxGroup
* @since JDK1.0
*/
public class Checkbox extends Component implements ItemSelectable {
/**
* The label of the Checkbox.
*/
String label;
/**
* The state of the Checkbox.
*/
boolean state;
/**
* The check box group.
*/
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 no label. The state of this
* check box is set to "off," and it is not part of any
* check box group.
* @since JDK1.0
*/
public Checkbox() {
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.
* @since JDK1.0
*/
public Checkbox(String label) {
this(label, false, null);
}
/**
* Creates a check box with the specified label. The state
* of this check box is as specified by the <code>state</code>
* argument, 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.
* @param state the initial state of this check box.
* @since JDK1.0
*/
public Checkbox(String label, boolean state) {
this(label, state, null);
}
/**
* 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 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.
* @since JDK1.1
*/
public Checkbox(String label, boolean state, CheckboxGroup group) {
this.label = label;
this.state = state;
this.group = group;
if (state && (group != null)) {
group.setSelectedCheckbox(this);
}
}
/**
* Constructs a Checkbox with the specified label, set to the
* specified state, and in the specified check box group.
*/
public Checkbox(String label, CheckboxGroup group, boolean state) {
this(label, state, group);
}
/**
* Construct a name for this component. Called by getName() when the
* name is null.
*/
String constructComponentName() {
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()
* @since JDK1.0
*/
public void addNotify() {
synchronized (getTreeLock()) {
if (peer == null)
peer = ((PeerBasedToolkit) 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 java.awt.Checkbox#setLabel
* @since JDK1.0
*/
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 java.awt.Checkbox#getLabel
* @since JDK1.0
*/
public synchronized void setLabel(String label) {
this.label = label;
CheckboxPeer peer = (CheckboxPeer) this.peer;
if (peer != null) {
peer.setLabel(label);
}
}
/**
* 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 java.awt.Checkbox#setState
* @since JDK1.0
*/
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.
* @param state the boolean state of the check box.
* @see java.awt.Checkbox#getState
* @since JDK1.0
*/
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 the 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 java.awt.Checkbox#setCheckboxGroup
* @since JDK1.0
*/
public CheckboxGroup getCheckboxGroup() {
return group;
}
/**
* Sets this check box's group to be 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.
* @param g the new check box group, or <code>null</code>
* to remove this check box from any check box group.
* @see java.awt.Checkbox#getCheckboxGroup
* @since JDK1.0
*/
public void setCheckboxGroup(CheckboxGroup g) {
// 6257119 : Brought over the code from j2se 1.4.2 to fix the
// bug
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);
}
// 6257119
}
/**
* Adds the specified item listener to receive item events from
* this check box.
* @param l the item listener.
* @see java.awt.event.ItemEvent
* @see java.awt.event.ItemListener
* @see java.awt.Checkbox#removeItemListener
* @since JDK1.1
*/
public synchronized void addItemListener(ItemListener l) {
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.
* @param l the item listener.
* @see java.awt.event.ItemEvent
* @see java.awt.event.ItemListener
* @see java.awt.Checkbox#addItemListener
* @since JDK1.1
*/
public synchronized void removeItemListener(ItemListener l) {
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 (ItemListener[]) AWTEventMulticaster.getListeners(
(EventListener)itemListener,
ItemListener.class);
}
// 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.
* @param e the event.
* @see java.awt.event.ItemEvent
* @see java.awt.Checkbox#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:
* <p><ul>
* <li>An <code>ItemListener</code> object is registered
* via <code>addItemListener</code>.
* <li>Item events are enabled via <code>enableEvents</code>.
* </ul>
* @param e the item event.
* @see java.awt.event.ItemEvent
* @see java.awt.event.ItemListener
* @see java.awt.Checkbox#addItemListener
* @see java.awt.Component#enableEvents
* @since JDK1.1
*/
protected void processItemEvent(ItemEvent e) {
if (itemListener != null) {
itemListener.itemStateChanged(e);
}
}
/**
* Returns the parameter string representing the state of
* this check box. This string is useful for debugging.
* @return the parameter string of this check box.
* @since JDK1.0
*/
protected String paramString() {
String str = super.paramString();
String label = this.label;
if (label != null) {
str += ",label=" + label;
}
return str + ",state=" + state;
}
/* Serialization support.
*/
private int checkboxSerializedDataVersion = 1;
private void writeObject(ObjectOutputStream s)
throws java.io.IOException {
s.defaultWriteObject();
AWTEventMulticaster.save(s, itemListenerK, itemListener);
s.writeObject(null);
}
private void readObject(ObjectInputStream s)
throws ClassNotFoundException, IOException {
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();
}
}
}