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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  *
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  * style="float:center; margin: 7px 10px;">
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      */
CheckboxGroup()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      */
getSelectedCheckbox()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
getCurrent()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      */
setSelectedCheckbox(Checkbox box)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
setCurrent(Checkbox box)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      */
toString()146     public String toString() {
147         return getClass().getName() + "[selectedCheckbox=" + selectedCheckbox + "]";
148     }
149 
150 }
151