2 * Copyright (C) 2006 The Android Open Source Project
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 package android.widget;
19 import android.content.Context;
20 import android.util.AttributeSet;
21 import android.view.MotionEvent;
22 import android.view.PointerIcon;
23 import android.widget.RemoteViews.RemoteView;
27 * A user interface element the user can tap or click to perform an action.
29 * <p>To display a button in an activity, add a button to the activity's layout XML file:</p>
33 * android:id="@+id/button_id"
34 * android:layout_height="wrap_content"
35 * android:layout_width="wrap_content"
36 * android:text="@string/self_destruct" /></pre>
38 * <p>To specify an action when the button is pressed, set a click
39 * listener on the button object in the corresponding activity code:</p>
42 * public class MyActivity extends Activity {
43 * protected void onCreate(Bundle savedInstanceState) {
44 * super.onCreate(savedInstanceState);
46 * setContentView(R.layout.content_layout_id);
48 * final Button button = findViewById(R.id.button_id);
49 * button.setOnClickListener(new View.OnClickListener() {
50 * public void onClick(View v) {
51 * // Code here executes on main thread after user presses button
57 * <p>The above snippet creates an instance of {@link View.OnClickListener} and wires
58 * the listener to the button using
59 * {@link #setOnClickListener setOnClickListener(View.OnClickListener)}.
60 * As a result, the system executes the code you write in {@code onClick(View)} after the
61 * user presses the button.</p>
63 * <p class="note">The system executes the code in {@code onClick} on the
64 * <a href="{@docRoot}guide/components/processes-and-threads.html#Threads">main thread</a>.
65 * This means your onClick code must execute quickly to avoid delaying your app's response
66 * to further user actions. See
67 * <a href="{@docRoot}training/articles/perf-anr.html">Keeping Your App Responsive</a>
68 * for more details.</p>
70 * <p>Every button is styled using the system's default button background, which is often
71 * different from one version of the platform to another. If you are not satisfied with the
72 * default button style, you can customize it. For more details and code samples, see the
73 * <a href="{@docRoot}guide/topics/ui/controls/button.html#Style">Styling Your Button</a>
76 * <p>For all XML style attributes available on Button see
77 * {@link android.R.styleable#Button Button Attributes},
78 * {@link android.R.styleable#TextView TextView Attributes},
79 * {@link android.R.styleable#View View Attributes}. See the
80 * {@link <a href="{@docRoot}guide/topics/ui/themes.html#ApplyingStyles">Styles and Themes</a>
81 * guide to learn how to implement and organize overrides to style-related attributes.</p>
84 * <a href="{@docRoot}guide/topics/ui/controls/button.html">Buttons Guide</a>
85 * {@link android.R.styleable#Button Styleable Button Attributes},
86 * {@link android.R.styleable#TextView Styleable TextView Attributes},
87 * {@link android.R.styleable#View Styleable View Attributes},
91 public class Button extends TextView {
94 * Simple constructor to use when creating a button from code.
96 * @param context The Context the Button is running in, through which it can
97 * access the current theme, resources, etc.
99 * @see #Button(Context, AttributeSet)
101 public Button(Context context) {
106 * {@link LayoutInflater} calls this constructor when inflating a Button from XML.
107 * The attributes defined by the current theme's
108 * {@link android.R.attr#buttonStyle android:buttonStyle}
109 * override base view attributes.
111 * You typically do not call this constructor to create your own button instance in code.
112 * However, you must override this constructor when
113 * <a href="{@docRoot}training/custom-views/index.html">creating custom views</a>.
115 * @param context The Context the view is running in, through which it can
116 * access the current theme, resources, etc.
117 * @param attrs The attributes of the XML Button tag being used to inflate the view.
119 * @see #Button(Context, AttributeSet, int)
120 * @see android.view.View#View(Context, AttributeSet)
122 public Button(Context context, AttributeSet attrs) {
123 this(context, attrs, com.android.internal.R.attr.buttonStyle);
127 * This constructor allows a Button subclass to use its own class-specific base style from a
128 * theme attribute when inflating. The attributes defined by the current theme's
129 * {@code defStyleAttr} override base view attributes.
131 * <p>For Button's base view attributes see
132 * {@link android.R.styleable#Button Button Attributes},
133 * {@link android.R.styleable#TextView TextView Attributes},
134 * {@link android.R.styleable#View View Attributes}.
136 * @param context The Context the Button is running in, through which it can
137 * access the current theme, resources, etc.
138 * @param attrs The attributes of the XML Button tag that is inflating the view.
139 * @param defStyleAttr The resource identifier of an attribute in the current theme
140 * whose value is the the resource id of a style. The specified style’s
141 * attribute values serve as default values for the button. Set this parameter
142 * to 0 to avoid use of default values.
143 * @see #Button(Context, AttributeSet, int, int)
144 * @see android.view.View#View(Context, AttributeSet, int)
146 public Button(Context context, AttributeSet attrs, int defStyleAttr) {
147 this(context, attrs, defStyleAttr, 0);
151 * This constructor allows a Button subclass to use its own class-specific base style from
152 * either a theme attribute or style resource when inflating. To see how the final value of a
153 * particular attribute is resolved based on your inputs to this constructor, see
154 * {@link android.view.View#View(Context, AttributeSet, int, int)}.
156 * @param context The Context the Button is running in, through which it can
157 * access the current theme, resources, etc.
158 * @param attrs The attributes of the XML Button tag that is inflating the view.
159 * @param defStyleAttr The resource identifier of an attribute in the current theme
160 * whose value is the the resource id of a style. The specified style’s
161 * attribute values serve as default values for the button. Set this parameter
162 * to 0 to avoid use of default values.
163 * @param defStyleRes The identifier of a style resource that
164 * supplies default values for the button, used only if
165 * defStyleAttr is 0 or cannot be found in the theme.
166 * Set this parameter to 0 to avoid use of default values.
168 * @see #Button(Context, AttributeSet, int)
169 * @see android.view.View#View(Context, AttributeSet, int, int)
171 public Button(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
172 super(context, attrs, defStyleAttr, defStyleRes);
176 public CharSequence getAccessibilityClassName() {
177 return Button.class.getName();
181 public PointerIcon onResolvePointerIcon(MotionEvent event, int pointerIndex) {
182 if (getPointerIcon() == null && isClickable() && isEnabled()) {
183 return PointerIcon.getSystemIcon(getContext(), PointerIcon.TYPE_HAND);
185 return super.onResolvePointerIcon(event, pointerIndex);