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;
21
22
23/**
24 * <p>
25 * A radio button is a two-states button that can be either checked or
26 * unchecked. When the radio button is unchecked, the user can press or click it
27 * to check it. However, contrary to a {@link android.widget.CheckBox}, a radio
28 * button cannot be unchecked by the user once checked.
29 * </p>
30 *
31 * <p>
32 * Radio buttons are normally used together in a
33 * {@link android.widget.RadioGroup}. When several radio buttons live inside
34 * a radio group, checking one radio button unchecks all the others.</p>
35 * </p>
36 *
37 * <p>See the <a href="{@docRoot}guide/topics/ui/controls/radiobutton.html">Radio Buttons</a>
38 * guide.</p>
39 *
40 * <p><strong>XML attributes</strong></p>
41 * <p>
42 * See {@link android.R.styleable#CompoundButton CompoundButton Attributes},
43 * {@link android.R.styleable#Button Button Attributes},
44 * {@link android.R.styleable#TextView TextView Attributes},
45 * {@link android.R.styleable#View View Attributes}
46 * </p>
47 */
48public class RadioButton extends CompoundButton {
49
50    public RadioButton(Context context) {
51        this(context, null);
52    }
53
54    public RadioButton(Context context, AttributeSet attrs) {
55        this(context, attrs, com.android.internal.R.attr.radioButtonStyle);
56    }
57
58    public RadioButton(Context context, AttributeSet attrs, int defStyleAttr) {
59        this(context, attrs, defStyleAttr, 0);
60    }
61
62    public RadioButton(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
63        super(context, attrs, defStyleAttr, defStyleRes);
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 CharSequence getAccessibilityClassName() {
82        return RadioButton.class.getName();
83    }
84}
85