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Android APIs
public class

Button

extends TextView
java.lang.Object
   ↳ android.view.View
     ↳ android.widget.TextView
       ↳ android.widget.Button
Known Direct Subclasses
Known Indirect Subclasses

Class Overview

Represents a push-button widget. Push-buttons can be pressed, or clicked, by the user to perform an action.

A typical use of a push-button in an activity would be the following: 

 public class MyActivity extends Activity {
     protected void onCreate(Bundle icicle) {
         super.onCreate(icicle);

         setContentView(R.layout.content_layout_id);

         final Button button = (Button) findViewById(R.id.button_id);
         button.setOnClickListener(new View.OnClickListener() {
             public void onClick(View v) {
                 // Perform action on click
             }
         });
     }
 }

However, instead of applying an OnClickListener to the button in your activity, you can assign a method to your button in the XML layout, using the android:onClick attribute. For example:

 <Button
     android:layout_height="wrap_content"
     android:layout_width="wrap_content"
     android:text="@string/self_destruct"
     android:onClick="selfDestruct" />

Now, when a user clicks the button, the Android system calls the activity's selfDestruct(View) method. In order for this to work, the method must be public and accept a View as its only parameter. For example:

 public void selfDestruct(View view) {
     // Kabloey
 }

The View passed into the method is a reference to the widget that was clicked.

Button style

Every Button is styled using the system's default button background, which is often different from one device to another and from one version of the platform to another. If you're not satisfied with the default button style and want to customize it to match the design of your application, then you can replace the button's background image with a state list drawable. A state list drawable is a drawable resource defined in XML that changes its image based on the current state of the button. Once you've defined a state list drawable in XML, you can apply it to your Button with the android:background attribute. For more information and an example, see State List Drawable.

See the Buttons guide.

XML attributes

See Button Attributes, TextView Attributes, View Attributes

Summary

[Expand]
Inherited XML Attributes
From class android.widget.TextView
From class android.view.View
[Expand]
Inherited Constants
From class android.view.View
[Expand]
Inherited Fields
From class android.view.View
Public Constructors
Button(Context context)
Button(Context context, AttributeSet attrs)
Button(Context context, AttributeSet attrs, int defStyle)
Public Methods
void onInitializeAccessibilityEvent(AccessibilityEvent event)
Initializes an AccessibilityEvent with information about this View which is the event source.
void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info)
Initializes an AccessibilityNodeInfo with information about this view.
[Expand]
Inherited Methods
From class android.widget.TextView
From class android.view.View
From class java.lang.Object
From interface android.graphics.drawable.Drawable.Callback
From interface android.view.KeyEvent.Callback
From interface android.view.ViewTreeObserver.OnPreDrawListener
From interface android.view.accessibility.AccessibilityEventSource

Public Constructors

public Button (Context context)

Added in API level 1

public Button (Context context, AttributeSet attrs)

Added in API level 1

public Button (Context context, AttributeSet attrs, int defStyle)

Added in API level 1

Public Methods

public void onInitializeAccessibilityEvent (AccessibilityEvent event)

Added in API level 14

Initializes an AccessibilityEvent with information about this View which is the event source. In other words, the source of an accessibility event is the view whose state change triggered firing the event.

Example: Setting the password property of an event in addition to properties set by the super implementation: 

 public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
     super.onInitializeAccessibilityEvent(event);
     event.setPassword(true);
 }

If an View.AccessibilityDelegate has been specified via calling setAccessibilityDelegate(AccessibilityDelegate) its onInitializeAccessibilityEvent(View, AccessibilityEvent) is responsible for handling this call.

Note: Always call the super implementation before adding information to the event, in case the default implementation has basic information to add.

Parameters
event The event to initialize.

public void onInitializeAccessibilityNodeInfo (AccessibilityNodeInfo info)

Added in API level 14

Initializes an AccessibilityNodeInfo with information about this view. The base implementation sets:

Subclasses should override this method, call the super implementation, and set additional attributes.

If an View.AccessibilityDelegate has been specified via calling setAccessibilityDelegate(AccessibilityDelegate) its onInitializeAccessibilityNodeInfo(View, AccessibilityNodeInfo) is responsible for handling this call.

Parameters
info The instance to initialize.