ImageObserver
, MenuContainer
, Serializable
, Accessible
public class Button extends Component implements Accessible
Quit
" button as it appears under the Solaris operating system:
The first view shows the button as it appears normally. The second view shows the button when it has input focus. Its outline is darkened to let the user know that it is an active object. The third view shows the button when the user clicks the mouse over the button, and thus requests that an action be performed.
The gesture of clicking on a button with the mouse is associated with one instance of ActionEvent
, which is sent out when the mouse is both pressed and released over the button. If an application is interested in knowing when the button has been pressed but not released, as a separate gesture, it can specialize processMouseEvent
, or it can register itself as a listener for mouse events by calling addMouseListener
. Both of these methods are defined by Component
, the abstract superclass of all components.
When a button is pressed and released, AWT sends an instance of ActionEvent
to the button, by calling processEvent
on the button. The button's processEvent
method receives all events for the button; it passes an action event along by calling its own processActionEvent
method. The latter method passes the action event on to any action listeners that have registered an interest in action events generated by this button.
If an application wants to perform some action based on a button being pressed and released, it should implement ActionListener
and register the new listener to receive events from this button, by calling the button's addActionListener
method. The application can make use of the button's action command as a messaging protocol.
Modifier and Type | Class | Description |
---|---|---|
protected class |
Button.AccessibleAWTButton |
This class implements accessibility support for the Button class. |
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
Constructor | Description |
---|---|
Button() |
Constructs a button with an empty string for its label. |
Button |
Constructs a button with the specified label. |
Modifier and Type | Method | Description |
---|---|---|
void |
addActionListener |
Adds the specified action listener to receive action events from this button. |
void |
addNotify() |
Creates the peer of the button. |
AccessibleContext |
getAccessibleContext() |
Gets the AccessibleContext associated with this Button . |
String |
getActionCommand() |
Returns the command name of the action event fired by this button. |
ActionListener[] |
getActionListeners() |
Returns an array of all the action listeners registered on this button. |
String |
getLabel() |
Gets the label of this button. |
<T extends EventListener> |
getListeners |
Returns an array of all the objects currently registered as FooListener s upon this Button . |
protected String |
paramString() |
Returns a string representing the state of this Button . |
protected void |
processActionEvent |
Processes action events occurring on this button by dispatching them to any registered ActionListener objects. |
protected void |
processEvent |
Processes events on this button. |
void |
removeActionListener |
Removes the specified action listener so that it no longer receives action events from this button. |
void |
setActionCommand |
Sets the command name for the action event fired by this button. |
void |
setLabel |
Sets the button's label to be the specified string. |
action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBaseline, getBaselineResizeBehavior, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeys, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPreferredSize, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusCycleRoot, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, minimumSize, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, postEvent, preferredSize, prepareImage, prepareImage, print, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, revalidate, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setMixingCutoutShape, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, update, validate
public Button() throws HeadlessException
HeadlessException
- if GraphicsEnvironment.isHeadless() returns truepublic Button(String label) throws HeadlessException
label
- a string label for the button, or null
for no labelHeadlessException
- if GraphicsEnvironment.isHeadless() returns truepublic void addNotify()
public String getLabel()
null
if the button has no label.public void setLabel(String label)
label
- the new label, or null
if the button has no label.public void setActionCommand(String command)
command
- a string used to set the button's action command. If the string is null
then the action command is set to match the label of the button.public String getActionCommand()
null
(default) then this method returns the label of the button.public void addActionListener(ActionListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
l
- the action listenerpublic void removeActionListener(ActionListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
l
- the action listenerpublic ActionListener[] getActionListeners()
ActionListener
s or an empty array if no action listeners are currently registeredpublic <T extends EventListener> T[] getListeners(Class<T> listenerType)
FooListener
s upon this Button
. FooListener
s are registered using the addFooListener
method. You can specify the listenerType
argument with a class literal, such as FooListener.class
. For example, you can query a Button b
for its action listeners with the following code:
ActionListener[] als = (ActionListener[])(b.getListeners(ActionListener.class));If no such listeners exist, this method returns an empty array.
getListeners
in class Component
T
- the type of the listenerslistenerType
- the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener
FooListener
s on this button, or an empty array if no such listeners have been addedClassCastException
- if listenerType
doesn't specify a class or interface that implements java.util.EventListener
protected void processEvent(AWTEvent e)
ActionEvent
, this method invokes the processActionEvent
method. Otherwise, it invokes processEvent
on the superclass. Note that if the event parameter is null
the behavior is unspecified and may result in an exception.
processEvent
in class Component
e
- the eventprotected void processActionEvent(ActionEvent e)
ActionListener
objects. This method is not called unless action events are enabled for this button. Action events are enabled when one of the following occurs:
ActionListener
object is registered via addActionListener
. enableEvents
. Note that if the event parameter is null
the behavior is unspecified and may result in an exception.
e
- the action eventprotected String paramString()
Button
. This method is intended to be used only for debugging purposes, and the content and format of the returned string may vary between implementations. The returned string may be empty but may not be null
.paramString
in class Component
@BeanProperty(expert=true, description="The AccessibleContext associated with this Button.") public AccessibleContext getAccessibleContext()
AccessibleContext
associated with this Button
. For buttons, the AccessibleContext
takes the form of an AccessibleAWTButton
. A new AccessibleAWTButton
instance is created if necessary.getAccessibleContext
in interface Accessible
getAccessibleContext
in class Component
AccessibleAWTButton
that serves as the AccessibleContext
of this Button
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
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https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/java/awt/Button.html