1/*
2 * Copyright (C) 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.widget;
18
19import android.content.Context;
20import android.util.AttributeSet;
21import android.view.accessibility.AccessibilityEvent;
22import android.view.accessibility.AccessibilityNodeInfo;
23
24import com.android.internal.R;
25
26
27/**
28 * <p>
29 * A radio button is a two-states button that can be either checked or
30 * unchecked. When the radio button is unchecked, the user can press or click it
31 * to check it. However, contrary to a {@link android.widget.CheckBox}, a radio
32 * button cannot be unchecked by the user once checked.
33 * </p>
34 *
35 * <p>
36 * Radio buttons are normally used together in a
37 * {@link android.widget.RadioGroup}. When several radio buttons live inside
38 * a radio group, checking one radio button unchecks all the others.</p>
39 * </p>
40 *
41 * <p>See the <a href="{@docRoot}guide/topics/ui/controls/radiobutton.html">Radio Buttons</a>
42 * guide.</p>
43 *
44 * <p><strong>XML attributes</strong></p>
45 * <p>
46 * See {@link android.R.styleable#CompoundButton CompoundButton Attributes},
47 * {@link android.R.styleable#Button Button Attributes},
48 * {@link android.R.styleable#TextView TextView Attributes},
49 * {@link android.R.styleable#View View Attributes}
50 * </p>
51 */
52public class RadioButton extends CompoundButton {
53
54    public RadioButton(Context context) {
55        this(context, null);
56    }
57
58    public RadioButton(Context context, AttributeSet attrs) {
59        this(context, attrs, com.android.internal.R.attr.radioButtonStyle);
60    }
61
62    public RadioButton(Context context, AttributeSet attrs, int defStyle) {
63        super(context, attrs, defStyle);
64    }
65
66    /**
67     * {@inheritDoc}
68     * <p>
69     * If the radio button is already checked, this method will not toggle the radio button.
70     */
71    @Override
72    public void toggle() {
73        // we override to prevent toggle when the radio is already
74        // checked (as opposed to check boxes widgets)
75        if (!isChecked()) {
76            super.toggle();
77        }
78    }
79
80    @Override
81    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
82        super.onInitializeAccessibilityEvent(event);
83        event.setClassName(RadioButton.class.getName());
84    }
85
86    @Override
87    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
88        super.onInitializeAccessibilityNodeInfo(info);
89        info.setClassName(RadioButton.class.getName());
90    }
91}
92