001 /*
002 * Copyright 1995-2004 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025 package java.awt;
026
027 /**
028 * The <code>CheckboxGroup</code> class is used to group together
029 * a set of <code>Checkbox</code> buttons.
030 * <p>
031 * Exactly one check box button in a <code>CheckboxGroup</code> can
032 * be in the "on" state at any given time. Pushing any
033 * button sets its state to "on" and forces any other button that
034 * is in the "on" state into the "off" state.
035 * <p>
036 * The following code example produces a new check box group,
037 * with three check boxes:
038 * <p>
039 * <hr><blockquote><pre>
040 * setLayout(new GridLayout(3, 1));
041 * CheckboxGroup cbg = new CheckboxGroup();
042 * add(new Checkbox("one", cbg, true));
043 * add(new Checkbox("two", cbg, false));
044 * add(new Checkbox("three", cbg, false));
045 * </pre></blockquote><hr>
046 * <p>
047 * This image depicts the check box group created by this example:
048 * <p>
049 * <img src="doc-files/CheckboxGroup-1.gif"
050 * alt="Shows three checkboxes, arranged vertically, labeled one, two, and three. Checkbox one is in the on state."
051 * ALIGN=center HSPACE=10 VSPACE=7>
052 * <p>
053 * @version 1.43 05/05/07
054 * @author Sami Shaio
055 * @see java.awt.Checkbox
056 * @since JDK1.0
057 */
058 public class CheckboxGroup implements java.io.Serializable {
059 /**
060 * The current choice.
061 * @serial
062 * @see #getCurrent()
063 * @see #setCurrent(Checkbox)
064 */
065 Checkbox selectedCheckbox = null;
066
067 /*
068 * JDK 1.1 serialVersionUID
069 */
070 private static final long serialVersionUID = 3729780091441768983L;
071
072 /**
073 * Creates a new instance of <code>CheckboxGroup</code>.
074 */
075 public CheckboxGroup() {
076 }
077
078 /**
079 * Gets the current choice from this check box group.
080 * The current choice is the check box in this
081 * group that is currently in the "on" state,
082 * or <code>null</code> if all check boxes in the
083 * group are off.
084 * @return the check box that is currently in the
085 * "on" state, or <code>null</code>.
086 * @see java.awt.Checkbox
087 * @see java.awt.CheckboxGroup#setSelectedCheckbox
088 * @since JDK1.1
089 */
090 public Checkbox getSelectedCheckbox() {
091 return getCurrent();
092 }
093
094 /**
095 * @deprecated As of JDK version 1.1,
096 * replaced by <code>getSelectedCheckbox()</code>.
097 */
098 @Deprecated
099 public Checkbox getCurrent() {
100 return selectedCheckbox;
101 }
102
103 /**
104 * Sets the currently selected check box in this group
105 * to be the specified check box.
106 * This method sets the state of that check box to "on" and
107 * sets all other check boxes in the group to be off.
108 * <p>
109 * If the check box argument is <tt>null</tt>, all check boxes
110 * in this check box group are deselected. If the check box argument
111 * belongs to a different check box group, this method does
112 * nothing.
113 * @param box the <code>Checkbox</code> to set as the
114 * current selection.
115 * @see java.awt.Checkbox
116 * @see java.awt.CheckboxGroup#getSelectedCheckbox
117 * @since JDK1.1
118 */
119 public void setSelectedCheckbox(Checkbox box) {
120 setCurrent(box);
121 }
122
123 /**
124 * @deprecated As of JDK version 1.1,
125 * replaced by <code>setSelectedCheckbox(Checkbox)</code>.
126 */
127 @Deprecated
128 public synchronized void setCurrent(Checkbox box) {
129 if (box != null && box.group != this ) {
130 return;
131 }
132 Checkbox oldChoice = this .selectedCheckbox;
133 this .selectedCheckbox = box;
134 if (oldChoice != null && oldChoice != box
135 && oldChoice.group == this ) {
136 oldChoice.setState(false);
137 }
138 if (box != null && oldChoice != box && !box.getState()) {
139 box.setStateInternal(true);
140 }
141 }
142
143 /**
144 * Returns a string representation of this check box group,
145 * including the value of its current selection.
146 * @return a string representation of this check box group.
147 */
148 public String toString() {
149 return getClass().getName() + "[selectedCheckbox="
150 + selectedCheckbox + "]";
151 }
152
153 }
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