ImageObserver
, ItemSelectable
, MenuContainer
, Serializable
, Accessible
public class Choice extends Component implements ItemSelectable, Accessible
Choice
class presents a pop-up menu of choices. The current choice is displayed as the title of the menu. The following code example produces a pop-up menu:
Choice ColorChooser = new Choice(); ColorChooser.add("Green"); ColorChooser.add("Red"); ColorChooser.add("Blue");
After this choice menu has been added to a panel, it appears as follows in its normal state:
In the picture, "Green"
is the current choice. Pushing the mouse button down on the object causes a menu to appear with the current choice highlighted.
Some native platforms do not support arbitrary resizing of Choice
components and the behavior of setSize()/getSize()
is bound by such limitations. Native GUI Choice
components' size are often bound by such attributes as font size and length of items contained within the Choice
.
Modifier and Type | Class | Description |
---|---|---|
protected class |
Choice.AccessibleAWTChoice |
This class implements accessibility support for the Choice 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 |
---|---|
Choice() |
Creates a new choice menu. |
Modifier and Type | Method | Description |
---|---|---|
void |
add |
Adds an item to this Choice menu. |
void |
addItem |
Obsolete as of Java 2 platform v1.1. |
void |
addItemListener |
Adds the specified item listener to receive item events from this Choice menu. |
void |
addNotify() |
Creates the Choice 's peer. |
int |
countItems() |
Deprecated. |
AccessibleContext |
getAccessibleContext() |
Gets the AccessibleContext associated with this Choice . |
String |
getItem |
Gets the string at the specified index in this Choice menu. |
int |
getItemCount() |
Returns the number of items in this Choice menu. |
ItemListener[] |
getItemListeners() |
Returns an array of all the item listeners registered on this choice. |
<T extends EventListener> |
getListeners |
Returns an array of all the objects currently registered as FooListener s upon this Choice . |
int |
getSelectedIndex() |
Returns the index of the currently selected item. |
String |
getSelectedItem() |
Gets a representation of the current choice as a string. |
Object[] |
getSelectedObjects() |
Returns an array (length 1) containing the currently selected item. |
void |
insert |
Inserts the item into this choice at the specified position. |
protected String |
paramString() |
Returns a string representing the state of this Choice menu. |
protected void |
processEvent |
Processes events on this choice. |
protected void |
processItemEvent |
Processes item events occurring on this Choice menu by dispatching them to any registered ItemListener objects. |
void |
remove |
Removes an item from the choice menu at the specified position. |
void |
remove |
Removes the first occurrence of item from the Choice menu. |
void |
removeAll() |
Removes all items from the choice menu. |
void |
removeItemListener |
Removes the specified item listener so that it no longer receives item events from this Choice menu. |
void |
select |
Sets the selected item in this Choice menu to be the item at the specified position. |
void |
select |
Sets the selected item in this Choice menu to be the item whose name is equal to 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 Choice() throws HeadlessException
By default, the first item added to the choice menu becomes the selected item, until a different selection is made by the user by calling one of the select
methods.
HeadlessException
- if GraphicsEnvironment.isHeadless() returns truepublic void addNotify()
Choice
's peer. This peer allows us to change the look of the Choice
without changing its functionality.public int getItemCount()
Choice
menu.Choice
menu@Deprecated public int countItems()
getItemCount()
.Choice
menu.Choice
menupublic String getItem(int index)
Choice
menu.index
- the index at which to beginpublic void add(String item)
Choice
menu.item
- the item to be addedNullPointerException
- if the item's value is null
public void addItem(String item)
add
method instead. Adds an item to this Choice
menu.
item
- the item to be addedNullPointerException
- if the item's value is equal to null
public void insert(String item, int index)
index
are shifted up by one to accommodate the new item. If index
is greater than or equal to the number of items in this choice, item
is added to the end of this choice. If the item is the first one being added to the choice, then the item becomes selected. Otherwise, if the selected item was one of the items shifted, the first item in the choice becomes the selected item. If the selected item was no among those shifted, it remains the selected item.
item
- the non-null
item to be insertedindex
- the position at which the item should be insertedIllegalArgumentException
- if index is less than 0public void remove(String item)
item
from the Choice
menu. If the item being removed is the currently selected item, then the first item in the choice becomes the selected item. Otherwise, the currently selected item remains selected (and the selected index is updated accordingly).item
- the item to remove from this Choice
menuIllegalArgumentException
- if the item doesn't exist in the choice menupublic void remove(int position)
position
- the position of the itemIndexOutOfBoundsException
- if the specified position is out of boundspublic void removeAll()
public String getSelectedItem()
public Object[] getSelectedObjects()
null
.getSelectedObjects
in interface ItemSelectable
null
public int getSelectedIndex()
public void select(int pos)
Choice
menu to be the item at the specified position. Note that this method should be primarily used to initially select an item in this component. Programmatically calling this method will not trigger an ItemEvent
. The only way to trigger an ItemEvent
is by user interaction.
pos
- the position of the selected itemIllegalArgumentException
- if the specified position is greater than the number of items or less than zeropublic void select(String str)
Choice
menu to be the item whose name is equal to the specified string. If more than one item matches (is equal to) the specified string, the one with the smallest index is selected. Note that this method should be primarily used to initially select an item in this component. Programmatically calling this method will not trigger an ItemEvent
. The only way to trigger an ItemEvent
is by user interaction.
str
- the specified stringpublic void addItemListener(ItemListener l)
Choice
menu. Item events are sent in response to user input, but not in response to calls to select
. If l is null
, no exception is thrown and no action is performed. Refer to AWT Threading Issues for details on AWT's threading model.
addItemListener
in interface ItemSelectable
l
- the item listenerpublic void removeItemListener(ItemListener l)
Choice
menu. If l is null
, no exception is thrown and no action is performed. 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 Choice
. 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 Choice 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 choice, 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
, it 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)
Choice
menu by dispatching them to any registered 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()
Choice
menu. 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
Choice
menupublic AccessibleContext getAccessibleContext()
AccessibleContext
associated with this Choice
. For Choice
components, the AccessibleContext
takes the form of an AccessibleAWTChoice
. A new AccessibleAWTChoice
instance is created if necessary.getAccessibleContext
in interface Accessible
getAccessibleContext
in class Component
AccessibleAWTChoice
that serves as the AccessibleContext
of this Choice
© 1993, 2023, Oracle and/or its affiliates. All rights reserved.
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).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/java/awt/Choice.html
getItemCount()
.