RadioButton.java revision 9066cfe9886ac131c34d59ed0e2d287b0e3c0087 
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><strong>XML attributes</strong></p>
38 * <p>
39 * See {@link android.R.styleable#CompoundButton CompoundButton Attributes},
40 * {@link android.R.styleable#Button Button Attributes},
41 * {@link android.R.styleable#TextView TextView Attributes},
42 * {@link android.R.styleable#View View Attributes}
43 * </p>
44 */
45public class RadioButton extends CompoundButton {
46
47    public RadioButton(Context context) {
48        this(context, null);
49    }
50
51    public RadioButton(Context context, AttributeSet attrs) {
52        this(context, attrs, com.android.internal.R.attr.radioButtonStyle);
53    }
54
55    public RadioButton(Context context, AttributeSet attrs, int defStyle) {
56        super(context, attrs, defStyle);
57    }
58
59    /**
60     * {@inheritDoc}
61     * <p>
62     * If the radio button is already checked, this method will not toggle the radio button.
63     */
64    @Override
65    public void toggle() {
66        // we override to prevent toggle when the radio is already
67        // checked (as opposed to check boxes widgets)
68        if (!isChecked()) {
69            super.toggle();
70        }
71    }
72}
73