Class Choice
- All Implemented Interfaces:
ImageObserver
,ItemSelectable
,MenuContainer
,Serializable
,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
.
- Since:
- 1.0
- See Also:
-
Nested Class Summary
Modifier and TypeClassDescriptionprotected class
This class implements accessibility support for theChoice
class.Nested classes/interfaces inherited from class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
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Field Summary
Fields inherited from class java.awt.Component
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
Fields inherited from interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionvoid
Adds an item to thisChoice
menu.void
Obsolete as of Java 2 platform v1.1.void
Adds the specified item listener to receive item events from thisChoice
menu.void
Creates theChoice
's peer.int
Deprecated.Gets theAccessibleContext
associated with thisChoice
.getItem
(int index) Gets the string at the specified index in thisChoice
menu.int
Returns the number of items in thisChoice
menu.Returns an array of all the item listeners registered on this choice.<T extends EventListener>
T[]getListeners
(Class<T> listenerType) Returns an array of all the objects currently registered asFooListener
s upon thisChoice
.int
Returns the index of the currently selected item.Gets a representation of the current choice as a string.Object[]
Returns an array (length 1) containing the currently selected item.void
Inserts the item into this choice at the specified position.protected String
Returns a string representing the state of thisChoice
menu.protected void
Processes events on this choice.protected void
Processes item events occurring on thisChoice
menu by dispatching them to any registeredItemListener
objects.void
remove
(int position) Removes an item from the choice menu at the specified position.void
Removes the first occurrence ofitem
from theChoice
menu.void
Removes all items from the choice menu.void
Removes the specified item listener so that it no longer receives item events from thisChoice
menu.void
select
(int pos) Sets the selected item in thisChoice
menu to be the item at the specified position.void
Sets the selected item in thisChoice
menu to be the item whose name is equal to the specified string.Methods inherited from class java.awt.Component
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
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Constructor Details
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Choice
Creates a new choice menu. The menu initially has no items in it.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.- Throws:
HeadlessException
- if GraphicsEnvironment.isHeadless() returns true- See Also:
-
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Method Details
-
addNotify
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getItemCount
public int getItemCount()Returns the number of items in thisChoice
menu.- Returns:
- the number of items in this
Choice
menu - Since:
- 1.1
- See Also:
-
countItems
Deprecated.As of JDK version 1.1, replaced bygetItemCount()
.Returns the number of items in thisChoice
menu.- Returns:
- the number of items in this
Choice
menu
-
getItem
Gets the string at the specified index in thisChoice
menu.- Parameters:
index
- the index at which to begin- Returns:
- the item at the specified index
- See Also:
-
add
Adds an item to thisChoice
menu.- Parameters:
item
- the item to be added- Throws:
NullPointerException
- if the item's value isnull
- Since:
- 1.1
-
addItem
Obsolete as of Java 2 platform v1.1. Please use theadd
method instead.Adds an item to this
Choice
menu.- Parameters:
item
- the item to be added- Throws:
NullPointerException
- if the item's value is equal tonull
-
insert
Inserts the item into this choice at the specified position. Existing items at an index greater than or equal toindex
are shifted up by one to accommodate the new item. Ifindex
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.
- Parameters:
item
- the non-null
item to be insertedindex
- the position at which the item should be inserted- Throws:
IllegalArgumentException
- if index is less than 0
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remove
Removes the first occurrence ofitem
from theChoice
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).- Parameters:
item
- the item to remove from thisChoice
menu- Throws:
IllegalArgumentException
- if the item doesn't exist in the choice menu- Since:
- 1.1
-
remove
public void remove(int position) Removes an item from the choice menu at the specified position. 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).- Parameters:
position
- the position of the item- Throws:
IndexOutOfBoundsException
- if the specified position is out of bounds- Since:
- 1.1
-
removeAll
public void removeAll()Removes all items from the choice menu.- Since:
- 1.1
- See Also:
-
getSelectedItem
Gets a representation of the current choice as a string.- Returns:
- a string representation of the currently selected item in this choice menu
- See Also:
-
getSelectedObjects
Returns an array (length 1) containing the currently selected item. If this choice has no items, returnsnull
.- Specified by:
getSelectedObjects
in interfaceItemSelectable
- Returns:
- the list of selected objects, or
null
- See Also:
-
getSelectedIndex
public int getSelectedIndex()Returns the index of the currently selected item. If nothing is selected, returns -1.- Returns:
- the index of the currently selected item, or -1 if nothing is currently selected
- See Also:
-
select
public void select(int pos) Sets the selected item in thisChoice
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 anItemEvent
is by user interaction.- Parameters:
pos
- the position of the selected item- Throws:
IllegalArgumentException
- if the specified position is greater than the number of items or less than zero- See Also:
-
select
Sets the selected item in thisChoice
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 anItemEvent
is by user interaction.- Parameters:
str
- the specified string- See Also:
-
addItemListener
Adds the specified item listener to receive item events from thisChoice
menu. Item events are sent in response to user input, but not in response to calls toselect
. If l isnull
, no exception is thrown and no action is performed.Refer to AWT Threading Issues for details on AWT's threading model.
- Specified by:
addItemListener
in interfaceItemSelectable
- Parameters:
l
- the item listener- Since:
- 1.1
- See Also:
-
removeItemListener
Removes the specified item listener so that it no longer receives item events from thisChoice
menu. If l isnull
, no exception is thrown and no action is performed.Refer to AWT Threading Issues for details on AWT's threading model.
- Specified by:
removeItemListener
in interfaceItemSelectable
- Parameters:
l
- the item listener- Since:
- 1.1
- See Also:
-
getItemListeners
Returns an array of all the item listeners registered on this choice.- Returns:
- all of this choice's
ItemListener
s or an empty array if no item listeners are currently registered - Since:
- 1.4
- See Also:
-
getListeners
Returns an array of all the objects currently registered asFooListener
s upon thisChoice
.FooListener
s are registered using theaddFooListener
method.You can specify the
listenerType
argument with a class literal, such asFooListener.class
. For example, you can query aChoice 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.- Overrides:
getListeners
in classComponent
- Type Parameters:
T
- the type of the listeners- Parameters:
listenerType
- the type of listeners requested; this parameter should specify an interface that descends fromjava.util.EventListener
- Returns:
- an array of all objects registered as
FooListener
s on this choice, or an empty array if no such listeners have been added - Throws:
ClassCastException
- iflistenerType
doesn't specify a class or interface that implementsjava.util.EventListener
- Since:
- 1.3
- See Also:
-
processEvent
Processes events on this choice. If the event is an instance ofItemEvent
, it invokes theprocessItemEvent
method. Otherwise, it calls its superclass'sprocessEvent
method.Note that if the event parameter is
null
the behavior is unspecified and may result in an exception.- Overrides:
processEvent
in classComponent
- Parameters:
e
- the event- Since:
- 1.1
- See Also:
-
processItemEvent
Processes item events occurring on thisChoice
menu by dispatching them to any registeredItemListener
objects.This method is not called unless item events are enabled for this component. Item events are enabled when one of the following occurs:
- An
ItemListener
object is registered viaaddItemListener
. - Item events are enabled via
enableEvents
.
Note that if the event parameter is
null
the behavior is unspecified and may result in an exception.- Parameters:
e
- the item event- Since:
- 1.1
- See Also:
- An
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paramString
Returns a string representing the state of thisChoice
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 benull
.- Overrides:
paramString
in classComponent
- Returns:
- the parameter string of this
Choice
menu
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getAccessibleContext
Gets theAccessibleContext
associated with thisChoice
. ForChoice
components, theAccessibleContext
takes the form of anAccessibleAWTChoice
. A newAccessibleAWTChoice
instance is created if necessary.- Specified by:
getAccessibleContext
in interfaceAccessible
- Overrides:
getAccessibleContext
in classComponent
- Returns:
- an
AccessibleAWTChoice
that serves as theAccessibleContext
of thisChoice
- Since:
- 1.3
-
getItemCount()
.