ImageObserver
, ItemSelectable
, MenuContainer
, Serializable
, Accessible
public class Checkbox extends Component implements ItemSelectable, Accessible
true
) or "off" (false
) state. Clicking on a check box changes its state from "on" to "off," or from "off" to "on." The following code example creates a set of check boxes in a grid layout:
setLayout(new GridLayout(3, 1)); add(new Checkbox("one", null, true)); add(new Checkbox("two")); add(new Checkbox("three"));
This image depicts the check boxes and grid layout created by this code example:
The button labeled one
is in the "on" state, and the other two are in the "off" state. In this example, which uses the GridLayout
class, the states of the three check boxes are set independently.
Alternatively, several check boxes can be grouped together under the control of a single object, using the CheckboxGroup
class. In a check box group, at most one button can be in the "on" state at any given time. Clicking on a check box to turn it on forces any other check box in the same group that is on into the "off" state.
Modifier and Type | Class | Description |
---|---|---|
protected class |
Checkbox.AccessibleAWTCheckbox |
This class implements accessibility support for the Checkbox 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 |
---|---|
Checkbox() |
Creates a check box with an empty string for its label. |
Checkbox |
Creates a check box with the specified label. |
Checkbox |
Creates a check box with the specified label and sets the specified state. |
Checkbox |
Constructs a Checkbox with the specified label, set to the specified state, and in the specified check box group. |
Checkbox |
Creates a check box with the specified label, in the specified check box group, and set to the specified state. |
Modifier and Type | Method | Description |
---|---|---|
void |
addItemListener |
Adds the specified item listener to receive item events from this check box. |
void |
addNotify() |
Creates the peer of the Checkbox. |
AccessibleContext |
getAccessibleContext() |
Gets the AccessibleContext associated with this Checkbox. |
CheckboxGroup |
getCheckboxGroup() |
Determines this check box's group. |
ItemListener[] |
getItemListeners() |
Returns an array of all the item listeners registered on this checkbox. |
String |
getLabel() |
Gets the label of this check box. |
<T extends EventListener> |
getListeners |
Returns an array of all the objects currently registered as FooListener s upon this Checkbox . |
Object[] |
getSelectedObjects() |
Returns an array (length 1) containing the checkbox label or null if the checkbox is not selected. |
boolean |
getState() |
Determines whether this check box is in the "on" or "off" state. |
protected String |
paramString() |
Returns a string representing the state of this Checkbox . |
protected void |
processEvent |
Processes events on this check box. |
protected void |
processItemEvent |
Processes item events occurring on this check box by dispatching them to any registered ItemListener objects. |
void |
removeItemListener |
Removes the specified item listener so that the item listener no longer receives item events from this check box. |
void |
setCheckboxGroup |
Sets this check box's group to the specified check box group. |
void |
setLabel |
Sets this check box's label to be the string argument. |
void |
setState |
Sets the state of this check box to the specified state. |
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 Checkbox() throws HeadlessException
HeadlessException
- if GraphicsEnvironment.isHeadless() returns truepublic Checkbox(String label) throws HeadlessException
label
- a string label for this check box, or null
for no label.HeadlessException
- if GraphicsEnvironment.isHeadless
returns true
public Checkbox(String label, boolean state) throws HeadlessException
label
- a string label for this check box, or null
for no labelstate
- the initial state of this check boxHeadlessException
- if GraphicsEnvironment.isHeadless
returns true
public Checkbox(String label, boolean state, CheckboxGroup group) throws HeadlessException
label
- a string label for this check box, or null
for no label.state
- the initial state of this check box.group
- a check box group for this check box, or null
for no group.HeadlessException
- if GraphicsEnvironment.isHeadless
returns true
public Checkbox(String label, CheckboxGroup group, boolean state) throws HeadlessException
label
- a string label for this check box, or null
for no label.group
- a check box group for this check box, or null
for no group.state
- the initial state of this check box.HeadlessException
- if GraphicsEnvironment.isHeadless
returns true
public void addNotify()
public String getLabel()
null
if this check box has no label.public void setLabel(String label)
label
- a string to set as the new label, or null
for no label.public boolean getState()
true
indicates the "on" state, and false
indicates the "off" state.public void setState(boolean state)
true
indicates the "on" state, and false
indicates the "off" state. Note that this method should be primarily used to initialize the state of the checkbox. Programmatically setting the state of the checkbox will not trigger an ItemEvent
. The only way to trigger an ItemEvent
is by user interaction.
state
- the boolean state of the check boxpublic Object[] getSelectedObjects()
getSelectedObjects
in interface ItemSelectable
null
public CheckboxGroup getCheckboxGroup()
null
if the check box is not part of a check box group.public void setCheckboxGroup(CheckboxGroup g)
If the state of this check box is true
and the new group already has a check box selected, this check box's state is changed to false
. If the state of this check box is true
and the new group has no check box selected, this check box becomes the selected checkbox for the new group and its state is true
.
g
- the new check box group, or null
to remove this check box from any check box grouppublic void addItemListener(ItemListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
addItemListener
in interface ItemSelectable
l
- the item listenerpublic void removeItemListener(ItemListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
removeItemListener
in interface ItemSelectable
l
- the item listenerpublic ItemListener[] getItemListeners()
ItemListener
s or an empty array if no item listeners are currently registeredpublic <T extends EventListener> T[] getListeners(Class<T> listenerType)
FooListener
s upon this Checkbox
. 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 Checkbox c
for its item listeners with the following code:
ItemListener[] ils = (ItemListener[])(c.getListeners(ItemListener.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 checkbox, 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)
ItemEvent
, this method invokes the processItemEvent
method. Otherwise, it calls its superclass's processEvent
method. 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 processItemEvent(ItemEvent e)
ItemListener
objects. This method is not called unless item events are enabled for this component. Item events are enabled when one of the following occurs:
ItemListener
object is registered via addItemListener
. enableEvents
. Note that if the event parameter is null
the behavior is unspecified and may result in an exception.
e
- the item eventprotected String paramString()
Checkbox
. 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
public AccessibleContext getAccessibleContext()
getAccessibleContext
in interface Accessible
getAccessibleContext
in class Component
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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.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/java/awt/Checkbox.html