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      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 
     17 package android.widget;
     18 
     19 import android.content.Context;
     20 import android.util.AttributeSet;
     21 import android.widget.RemoteViews.RemoteView;
     22 
     23 
     24 /**
     25  * Represents a push-button widget. Push-buttons can be
     26  * pressed, or clicked, by the user to perform an action.
     27 
     28  * <p>A typical use of a push-button in an activity would be the following:
     29  * </p>
     30  *
     31  * <pre>
     32  * public class MyActivity extends Activity {
     33  *     protected void onCreate(Bundle icicle) {
     34  *         super.onCreate(icicle);
     35  *
     36  *         setContentView(R.layout.content_layout_id);
     37  *
     38  *         final Button button = (Button) findViewById(R.id.button_id);
     39  *         button.setOnClickListener(new View.OnClickListener() {
     40  *             public void onClick(View v) {
     41  *                 // Perform action on click
     42  *             }
     43  *         });
     44  *     }
     45  * }</pre>
     46  *
     47  * <p>However, instead of applying an {@link android.view.View.OnClickListener OnClickListener} to
     48  * the button in your activity, you can assign a method to your button in the XML layout,
     49  * using the {@link android.R.attr#onClick android:onClick} attribute. For example:</p>
     50  *
     51  * <pre>
     52  * &lt;Button
     53  *     android:layout_height="wrap_content"
     54  *     android:layout_width="wrap_content"
     55  *     android:text="@string/self_destruct"
     56  *     android:onClick="selfDestruct" /&gt;</pre>
     57  *
     58  * <p>Now, when a user clicks the button, the Android system calls the activity's {@code
     59  * selfDestruct(View)} method. In order for this to work, the method must be public and accept
     60  * a {@link android.view.View} as its only parameter. For example:</p>
     61  *
     62  * <pre>
     63  * public void selfDestruct(View view) {
     64  *     // Kabloey
     65  * }</pre>
     66  *
     67  * <p>The {@link android.view.View} passed into the method is a reference to the widget
     68  * that was clicked.</p>
     69  *
     70  * <h3>Button style</h3>
     71  *
     72  * <p>Every Button is styled using the system's default button background, which is often different
     73  * from one device to another and from one version of the platform to another. If you're not
     74  * satisfied with the default button style and want to customize it to match the design of your
     75  * application, then you can replace the button's background image with a <a
     76  * href="{@docRoot}guide/topics/resources/drawable-resource.html#StateList">state list drawable</a>.
     77  * A state list drawable is a drawable resource defined in XML that changes its image based on
     78  * the current state of the button. Once you've defined a state list drawable in XML, you can apply
     79  * it to your Button with the {@link android.R.attr#background android:background}
     80  * attribute. For more information and an example, see <a
     81  * href="{@docRoot}guide/topics/resources/drawable-resource.html#StateList">State List
     82  * Drawable</a>.</p>
     83  *
     84  * <p>See the <a href="{@docRoot}guide/topics/ui/controls/button.html">Buttons</a>
     85  * guide.</p>
     86  *
     87  * <p><strong>XML attributes</strong></p>
     88  * <p>
     89  * See {@link android.R.styleable#Button Button Attributes},
     90  * {@link android.R.styleable#TextView TextView Attributes},
     91  * {@link android.R.styleable#View View Attributes}
     92  * </p>
     93  */
     94 @RemoteView
     95 public class Button extends TextView {
     96     public Button(Context context) {
     97         this(context, null);
     98     }
     99 
    100     public Button(Context context, AttributeSet attrs) {
    101         this(context, attrs, com.android.internal.R.attr.buttonStyle);
    102     }
    103 
    104     public Button(Context context, AttributeSet attrs, int defStyleAttr) {
    105         this(context, attrs, defStyleAttr, 0);
    106     }
    107 
    108     public Button(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
    109         super(context, attrs, defStyleAttr, defStyleRes);
    110     }
    111 
    112     @Override
    113     public CharSequence getAccessibilityClassName() {
    114         return Button.class.getName();
    115     }
    116 }
    117