java.lang.Object
java.awt.Component
java.awt.Checkbox
public class Checkbox
A check box is a graphical component that can be in either an "on" (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.
GridLayout, CheckboxGroup, Serialized Form
Checkbox()
Checkbox(String label)
Checkbox(String label, boolean state)
Checkbox(String label, boolean state, CheckboxGroup group)
Checkbox(String label, CheckboxGroup group, boolean 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, 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, getPeer, 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, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, update, validate Checkbox
public Checkbox()
throws HeadlessException
HeadlessException - if GraphicsEnvironment.isHeadless() returns true
GraphicsEnvironment.isHeadless()
public Checkbox(String label)
throws HeadlessException
label - a string label for this check box, or null for no label.
HeadlessException - if GraphicsEnvironment.isHeadless returns true
GraphicsEnvironment.isHeadless()
public Checkbox(String label,
boolean state)
throws HeadlessException
label - a string label for this check box, or null for no label
state - the initial state of this check box
HeadlessException - if GraphicsEnvironment.isHeadless returns true
GraphicsEnvironment.isHeadless()
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
GraphicsEnvironment.isHeadless()
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
GraphicsEnvironment.isHeadless()
public void addNotify()
addNotify in class Component
Toolkit.createCheckbox(java.awt.Checkbox), Component.getToolkit()
public String getLabel()
null if this check box has no label.
setLabel(String)
public void setLabel(String label)
label - a string to set as the new label, or null for no label.
getLabel()
public boolean getState()
true indicates the "on" state, and false indicates the "off" state.
setState(boolean)
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 box
getState()
public Object[] getSelectedObjects()
getSelectedObjects in interface ItemSelectable
ItemSelectable
public CheckboxGroup getCheckboxGroup()
null if the check box is not part of a check box group.
setCheckboxGroup(CheckboxGroup)
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 group
getCheckboxGroup()
public void addItemListener(ItemListener l)
addItemListener in interface ItemSelectable
l - the item listener
removeItemListener(java.awt.event.ItemListener), getItemListeners(), setState(boolean), ItemEvent, ItemListener
public void removeItemListener(ItemListener l)
removeItemListener in interface ItemSelectable
l - the item listener
addItemListener(java.awt.event.ItemListener), getItemListeners(), ItemEvent, ItemListener
public ItemListener[] getItemListeners()
ItemListeners or an empty array if no item listeners are currently registered
addItemListener(java.awt.event.ItemListener), removeItemListener(java.awt.event.ItemListener), ItemEvent, ItemListener
public <T extends EventListener> T[] getListeners(Class<T> listenerType)
FooListeners upon this Checkbox. FooListeners 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
listenerType - the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener
FooListeners on this checkbox, or an empty array if no such listeners have been added
ClassCastException - if listenerType doesn't specify a class or interface that implements java.util.EventListener
getItemListeners()
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 event
ItemEvent, processItemEvent(java.awt.event.ItemEvent)
protected 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 event
ItemEvent, ItemListener, addItemListener(java.awt.event.ItemListener), Component.enableEvents(long)
protected 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
Copyright © 2004, 2010 Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
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