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    1   /*
    2    * Copyright (c) 1995, 2004, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   package java.awt;
   26   
   27   /**
   28    * The <code>CheckboxGroup</code> class is used to group together
   29    * a set of <code>Checkbox</code> buttons.
   30    * <p>
   31    * Exactly one check box button in a <code>CheckboxGroup</code> can
   32    * be in the "on" state at any given time. Pushing any
   33    * button sets its state to "on" and forces any other button that
   34    * is in the "on" state into the "off" state.
   35    * <p>
   36    * The following code example produces a new check box group,
   37    * with three check boxes:
   38    * <p>
   39    * <hr><blockquote><pre>
   40    * setLayout(new GridLayout(3, 1));
   41    * CheckboxGroup cbg = new CheckboxGroup();
   42    * add(new Checkbox("one", cbg, true));
   43    * add(new Checkbox("two", cbg, false));
   44    * add(new Checkbox("three", cbg, false));
   45    * </pre></blockquote><hr>
   46    * <p>
   47    * This image depicts the check box group created by this example:
   48    * <p>
   49    * <img src="doc-files/CheckboxGroup-1.gif"
   50    * alt="Shows three checkboxes, arranged vertically, labeled one, two, and three. Checkbox one is in the on state."
   51    * ALIGN=center HSPACE=10 VSPACE=7>
   52    * <p>
   53    * @author      Sami Shaio
   54    * @see         java.awt.Checkbox
   55    * @since       JDK1.0
   56    */
   57   public class CheckboxGroup implements java.io.Serializable {
   58       /**
   59        * The current choice.
   60        * @serial
   61        * @see #getCurrent()
   62        * @see #setCurrent(Checkbox)
   63        */
   64       Checkbox selectedCheckbox = null;
   65   
   66       /*
   67        * JDK 1.1 serialVersionUID
   68        */
   69       private static final long serialVersionUID = 3729780091441768983L;
   70   
   71       /**
   72        * Creates a new instance of <code>CheckboxGroup</code>.
   73        */
   74       public CheckboxGroup() {
   75       }
   76   
   77       /**
   78        * Gets the current choice from this check box group.
   79        * The current choice is the check box in this
   80        * group that is currently in the "on" state,
   81        * or <code>null</code> if all check boxes in the
   82        * group are off.
   83        * @return   the check box that is currently in the
   84        *                 "on" state, or <code>null</code>.
   85        * @see      java.awt.Checkbox
   86        * @see      java.awt.CheckboxGroup#setSelectedCheckbox
   87        * @since    JDK1.1
   88        */
   89       public Checkbox getSelectedCheckbox() {
   90           return getCurrent();
   91       }
   92   
   93       /**
   94        * @deprecated As of JDK version 1.1,
   95        * replaced by <code>getSelectedCheckbox()</code>.
   96        */
   97       @Deprecated
   98       public Checkbox getCurrent() {
   99           return selectedCheckbox;
  100       }
  101   
  102       /**
  103        * Sets the currently selected check box in this group
  104        * to be the specified check box.
  105        * This method sets the state of that check box to "on" and
  106        * sets all other check boxes in the group to be off.
  107        * <p>
  108        * If the check box argument is <tt>null</tt>, all check boxes
  109        * in this check box group are deselected. If the check box argument
  110        * belongs to a different check box group, this method does
  111        * nothing.
  112        * @param     box   the <code>Checkbox</code> to set as the
  113        *                      current selection.
  114        * @see      java.awt.Checkbox
  115        * @see      java.awt.CheckboxGroup#getSelectedCheckbox
  116        * @since    JDK1.1
  117        */
  118       public void setSelectedCheckbox(Checkbox box) {
  119           setCurrent(box);
  120       }
  121   
  122       /**
  123        * @deprecated As of JDK version 1.1,
  124        * replaced by <code>setSelectedCheckbox(Checkbox)</code>.
  125        */
  126       @Deprecated
  127       public synchronized void setCurrent(Checkbox box) {
  128           if (box != null && box.group != this) {
  129               return;
  130           }
  131           Checkbox oldChoice = this.selectedCheckbox;
  132           this.selectedCheckbox = box;
  133           if (oldChoice != null && oldChoice != box && oldChoice.group == this) {
  134               oldChoice.setState(false);
  135           }
  136           if (box != null && oldChoice != box && !box.getState()) {
  137               box.setStateInternal(true);
  138           }
  139       }
  140   
  141       /**
  142        * Returns a string representation of this check box group,
  143        * including the value of its current selection.
  144        * @return    a string representation of this check box group.
  145        */
  146       public String toString() {
  147           return getClass().getName() + "[selectedCheckbox=" + selectedCheckbox + "]";
  148       }
  149   
  150   }

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