diff options
| -rw-r--r-- | core/java/android/widget/Button.java | 159 |
1 files changed, 110 insertions, 49 deletions
diff --git a/core/java/android/widget/Button.java b/core/java/android/widget/Button.java index 09ba553cbf3e..452ff17ee3d9 100644 --- a/core/java/android/widget/Button.java +++ b/core/java/android/widget/Button.java @@ -24,89 +24,150 @@ import android.widget.RemoteViews.RemoteView; /** - * Represents a push-button widget. Push-buttons can be - * pressed, or clicked, by the user to perform an action. - - * <p>A typical use of a push-button in an activity would be the following: - * </p> + * A user interface element the user can tap or click to perform an action. + * + * <p>To display a button in an activity, add a button to the activity's layout XML file:</p> + * + * <pre> + * <Button + * android:id="@+id/button_id" + * android:layout_height="wrap_content" + * android:layout_width="wrap_content" + * android:text="@string/self_destruct" /></pre> + * + * <p>To specify an action when the button is pressed, set a click + * listener on the button object in the corresponding activity code:</p> * * <pre> * public class MyActivity extends Activity { - * protected void onCreate(Bundle icicle) { - * super.onCreate(icicle); + * protected void onCreate(Bundle savedInstanceState) { + * super.onCreate(savedInstanceState); * * setContentView(R.layout.content_layout_id); * * final Button button = findViewById(R.id.button_id); * button.setOnClickListener(new View.OnClickListener() { * public void onClick(View v) { - * // Perform action on click + * // Code here executes on main thread after user presses button * } * }); * } * }</pre> * - * <p>However, instead of applying an {@link android.view.View.OnClickListener OnClickListener} to - * the button in your activity, you can assign a method to your button in the XML layout, - * using the {@link android.R.attr#onClick android:onClick} attribute. For example:</p> - * - * <pre> - * <Button - * android:layout_height="wrap_content" - * android:layout_width="wrap_content" - * android:text="@string/self_destruct" - * android:onClick="selfDestruct" /></pre> - * - * <p>Now, when a user clicks the button, the Android system calls the activity's {@code - * selfDestruct(View)} method. In order for this to work, the method must be public and accept - * a {@link android.view.View} as its only parameter. For example:</p> - * - * <pre> - * public void selfDestruct(View view) { - * // Kabloey - * }</pre> - * - * <p>The {@link android.view.View} passed into the method is a reference to the widget - * that was clicked.</p> - * - * <h3>Button style</h3> + * <p>The above snippet creates an instance of {@link View.OnClickListener} and wires + * the listener to the button using + * {@link #setOnClickListener setOnClickListener(View.OnClickListener)}. + * As a result, the system executes the code you write in {@code onClick(View)} after the + * user presses the button.</p> * - * <p>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 <a - * href="{@docRoot}guide/topics/resources/drawable-resource.html#StateList">state list drawable</a>. - * 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 {@link android.R.attr#background android:background} - * attribute. For more information and an example, see <a - * href="{@docRoot}guide/topics/resources/drawable-resource.html#StateList">State List - * Drawable</a>.</p> + * <p class="note">The system executes the code in {@code onClick} on the + * <a href="{@docRoot}guide/components/processes-and-threads.html#Threads">main thread</a>. + * This means your onClick code must execute quickly to avoid delaying your app's response + * to further user actions. See + * <a href="{@docRoot}training/articles/perf-anr.html">Keeping Your App Responsive</a> + * for more details.</p> * - * <p>See the <a href="{@docRoot}guide/topics/ui/controls/button.html">Buttons</a> + * <p>Every button is styled using the system's default button background, which is often + * different from one version of the platform to another. If you are not satisfied with the + * default button style, you can customize it. For more details and code samples, see the + * <a href="{@docRoot}guide/topics/ui/controls/button.html#Style">Styling Your Button</a> * guide.</p> * - * <p><strong>XML attributes</strong></p> - * <p> - * See {@link android.R.styleable#Button Button Attributes}, + * <p>For all XML style attributes available on Button see + * {@link android.R.styleable#Button Button Attributes}, * {@link android.R.styleable#TextView TextView Attributes}, - * {@link android.R.styleable#View View Attributes} - * </p> + * {@link android.R.styleable#View View Attributes}. See the + * {@link <a href="{@docRoot}guide/topics/ui/themes.html#ApplyingStyles">Styles and Themes</a> + * guide to learn how to implement and organize overrides to style-related attributes.</p> + * + * @see + * <a href="{@docRoot}guide/topics/ui/controls/button.html">Buttons Guide</a> + * {@link android.R.styleable#Button Styleable Button Attributes}, + * {@link android.R.styleable#TextView Styleable TextView Attributes}, + * {@link android.R.styleable#View Styleable View Attributes}, + * */ @RemoteView public class Button extends TextView { + + /** + * Simple constructor to use when creating a button from code. + * + * @param context The Context the Button is running in, through which it can + * access the current theme, resources, etc. + * + * @see #Button(Context, AttributeSet) + */ public Button(Context context) { this(context, null); } + /** + * {@link LayoutInflater} calls this constructor when inflating a Button from XML. + * The attributes defined by the current theme's + * {@link android.R.attr#buttonStyle android:buttonStyle} + * override base view attributes. + * + * You typically do not call this constructor to create your own button instance in code. + * However, you must override this constructor when + * <a href="{@docRoot}training/custom-views/index.html">creating custom views</a>. + * + * @param context The Context the view is running in, through which it can + * access the current theme, resources, etc. + * @param attrs The attributes of the XML Button tag being used to inflate the view. + * + * @see #Button(Context, AttributeSet, int) + * @see android.view.View#View(Context, AttributeSet) + */ public Button(Context context, AttributeSet attrs) { this(context, attrs, com.android.internal.R.attr.buttonStyle); } + /** + * This constructor allows a Button subclass to use its own class-specific base style from a + * theme attribute when inflating. The attributes defined by the current theme's + * {@code defStyleAttr} override base view attributes. + * + * <p>For Button's base view attributes see + * {@link android.R.styleable#Button Button Attributes}, + * {@link android.R.styleable#TextView TextView Attributes}, + * {@link android.R.styleable#View View Attributes}. + * + * @param context The Context the Button is running in, through which it can + * access the current theme, resources, etc. + * @param attrs The attributes of the XML Button tag that is inflating the view. + * @param defStyleAttr The resource identifier of an attribute in the current theme + * whose value is the the resource id of a style. The specified style’s + * attribute values serve as default values for the button. Set this parameter + * to 0 to avoid use of default values. + * @see #Button(Context, AttributeSet, int, int) + * @see android.view.View#View(Context, AttributeSet, int) + */ public Button(Context context, AttributeSet attrs, int defStyleAttr) { this(context, attrs, defStyleAttr, 0); } + /** + * This constructor allows a Button subclass to use its own class-specific base style from + * either a theme attribute or style resource when inflating. To see how the final value of a + * particular attribute is resolved based on your inputs to this constructor, see + * {@link android.view.View#View(Context, AttributeSet, int, int)}. + * + * @param context The Context the Button is running in, through which it can + * access the current theme, resources, etc. + * @param attrs The attributes of the XML Button tag that is inflating the view. + * @param defStyleAttr The resource identifier of an attribute in the current theme + * whose value is the the resource id of a style. The specified style’s + * attribute values serve as default values for the button. Set this parameter + * to 0 to avoid use of default values. + * @param defStyleRes The identifier of a style resource that + * supplies default values for the button, used only if + * defStyleAttr is 0 or cannot be found in the theme. + * Set this parameter to 0 to avoid use of default values. + * + * @see #Button(Context, AttributeSet, int) + * @see android.view.View#View(Context, AttributeSet, int, int) + */ public Button(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); } |