- java.lang.Object
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- java.awt.Component
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- java.awt.Choice
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- All Implemented Interfaces:
ImageObserver,ItemSelectable,MenuContainer,Serializable,Accessible
public class Choice extends Component implements ItemSelectable, Accessible
TheChoiceclass 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
Choicecomponents and the behavior ofsetSize()/getSize()is bound by such limitations. Native GUIChoicecomponents' size are often bound by such attributes as font size and length of items contained within theChoice.- Since:
- 1.0
- See Also:
- Serialized Form
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Nested Class Summary
Nested Classes Modifier and Type Class Description protected classChoice.AccessibleAWTChoiceThis class implements accessibility support for theChoiceclass.-
Nested classes/interfaces declared in class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
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Field Summary
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Fields declared in class java.awt.Component
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
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Fields declared in interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
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Constructor Summary
Constructors Constructor Description Choice()Creates a new choice menu.
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Method Summary
All Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description voidadd(String item)Adds an item to thisChoicemenu.voidaddItem(String item)Obsolete as of Java 2 platform v1.1.voidaddItemListener(ItemListener l)Adds the specified item listener to receive item events from thisChoicemenu.voidaddNotify()Creates theChoice's peer.intcountItems()Deprecated.As of JDK version 1.1, replaced bygetItemCount().AccessibleContextgetAccessibleContext()Gets theAccessibleContextassociated with thisChoice.StringgetItem(int index)Gets the string at the specified index in thisChoicemenu.intgetItemCount()Returns the number of items in thisChoicemenu.ItemListener[]getItemListeners()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 asFooListeners upon thisChoice.intgetSelectedIndex()Returns the index of the currently selected item.StringgetSelectedItem()Gets a representation of the current choice as a string.Object[]getSelectedObjects()Returns an array (length 1) containing the currently selected item.voidinsert(String item, int index)Inserts the item into this choice at the specified position.protected StringparamString()Returns a string representing the state of thisChoicemenu.protected voidprocessEvent(AWTEvent e)Processes events on this choice.protected voidprocessItemEvent(ItemEvent e)Processes item events occurring on thisChoicemenu by dispatching them to any registeredItemListenerobjects.voidremove(int position)Removes an item from the choice menu at the specified position.voidremove(String item)Removes the first occurrence ofitemfrom theChoicemenu.voidremoveAll()Removes all items from the choice menu.voidremoveItemListener(ItemListener l)Removes the specified item listener so that it no longer receives item events from thisChoicemenu.voidselect(int pos)Sets the selected item in thisChoicemenu to be the item at the specified position.voidselect(String str)Sets the selected item in thisChoicemenu to be the item whose name is equal to the specified string.-
Methods declared in 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 Detail
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Choice
public Choice() throws HeadlessExceptionCreates 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
selectmethods.- Throws:
HeadlessException- if GraphicsEnvironment.isHeadless() returns true- See Also:
GraphicsEnvironment.isHeadless(),select(int),select(java.lang.String)
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Method Detail
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addNotify
public void addNotify()
Creates theChoice's peer. This peer allows us to change the look of theChoicewithout changing its functionality.- Overrides:
addNotifyin classComponent- See Also:
Component.getToolkit()
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getItemCount
public int getItemCount()
Returns the number of items in thisChoicemenu.- Returns:
- the number of items in this
Choicemenu - Since:
- 1.1
- See Also:
getItem(int)
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countItems
@Deprecated public int countItems()
Deprecated.As of JDK version 1.1, replaced bygetItemCount().Returns the number of items in thisChoicemenu.- Returns:
- the number of items in this
Choicemenu
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getItem
public String getItem(int index)
Gets the string at the specified index in thisChoicemenu.- Parameters:
index- the index at which to begin- Returns:
- the item at the specified index
- See Also:
getItemCount()
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add
public void add(String item)
Adds an item to thisChoicemenu.- Parameters:
item- the item to be added- Throws:
NullPointerException- if the item's value isnull- Since:
- 1.1
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addItem
public void addItem(String item)
Obsolete as of Java 2 platform v1.1. Please use theaddmethod instead.Adds an item to this
Choicemenu.- Parameters:
item- the item to be added- Throws:
NullPointerException- if the item's value is equal tonull
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insert
public void insert(String item, int index)
Inserts the item into this choice at the specified position. Existing items at an index greater than or equal toindexare shifted up by one to accommodate the new item. Ifindexis greater than or equal to the number of items in this choice,itemis 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-nullitem 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
public void remove(String item)
Removes the first occurrence ofitemfrom theChoicemenu. 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 thisChoicemenu- Throws:
IllegalArgumentException- if the item doesn't exist in the choice menu- Since:
- 1.1
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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
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removeAll
public void removeAll()
Removes all items from the choice menu.- Since:
- 1.1
- See Also:
remove(java.lang.String)
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getSelectedItem
public String 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:
getSelectedIndex()
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getSelectedObjects
public Object[] getSelectedObjects()
Returns an array (length 1) containing the currently selected item. If this choice has no items, returnsnull.- Specified by:
getSelectedObjectsin interfaceItemSelectable- Returns:
- the list of selected objects, or
null - See Also:
ItemSelectable
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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:
getSelectedItem()
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select
public void select(int pos)
Sets the selected item in thisChoicemenu 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 anItemEventis 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:
getSelectedItem(),getSelectedIndex()
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select
public void select(String str)
Sets the selected item in thisChoicemenu 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 anItemEventis by user interaction.- Parameters:
str- the specified string- See Also:
getSelectedItem(),getSelectedIndex()
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addItemListener
public void addItemListener(ItemListener l)
Adds the specified item listener to receive item events from thisChoicemenu. 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:
addItemListenerin interfaceItemSelectable- Parameters:
l- the item listener- Since:
- 1.1
- See Also:
removeItemListener(java.awt.event.ItemListener),getItemListeners(),select(int),ItemEvent,ItemListener
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removeItemListener
public void removeItemListener(ItemListener l)
Removes the specified item listener so that it no longer receives item events from thisChoicemenu. 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:
removeItemListenerin interfaceItemSelectable- Parameters:
l- the item listener- Since:
- 1.1
- See Also:
addItemListener(java.awt.event.ItemListener),getItemListeners(),ItemEvent,ItemListener
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getItemListeners
public ItemListener[] getItemListeners()
Returns an array of all the item listeners registered on this choice.- Returns:
- all of this choice's
ItemListeners or an empty array if no item listeners are currently registered - Since:
- 1.4
- See Also:
addItemListener(java.awt.event.ItemListener),removeItemListener(java.awt.event.ItemListener),ItemEvent,ItemListener
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getListeners
public <T extends EventListener> T[] getListeners(Class<T> listenerType)
Returns an array of all the objects currently registered asFooListeners upon thisChoice.FooListeners are registered using theaddFooListenermethod.You can specify the
listenerTypeargument with a class literal, such asFooListener.class. For example, you can query aChoice cfor 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:
getListenersin 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
FooListeners on this choice, or an empty array if no such listeners have been added - Throws:
ClassCastException- iflistenerTypedoesn't specify a class or interface that implementsjava.util.EventListener- Since:
- 1.3
- See Also:
getItemListeners()
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processEvent
protected void processEvent(AWTEvent e)
Processes events on this choice. If the event is an instance ofItemEvent, it invokes theprocessItemEventmethod. Otherwise, it calls its superclass'sprocessEventmethod.Note that if the event parameter is
nullthe behavior is unspecified and may result in an exception.- Overrides:
processEventin classComponent- Parameters:
e- the event- Since:
- 1.1
- See Also:
ItemEvent,processItemEvent(java.awt.event.ItemEvent)
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processItemEvent
protected void processItemEvent(ItemEvent e)
Processes item events occurring on thisChoicemenu by dispatching them to any registeredItemListenerobjects.This method is not called unless item events are enabled for this component. Item events are enabled when one of the following occurs:
- An
ItemListenerobject is registered viaaddItemListener. - Item events are enabled via
enableEvents.
Note that if the event parameter is
nullthe behavior is unspecified and may result in an exception.- Parameters:
e- the item event- Since:
- 1.1
- See Also:
ItemEvent,ItemListener,addItemListener(ItemListener),Component.enableEvents(long)
- An
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paramString
protected String paramString()
Returns a string representing the state of thisChoicemenu. 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:
paramStringin classComponent- Returns:
- the parameter string of this
Choicemenu
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getAccessibleContext
public AccessibleContext getAccessibleContext()
Gets theAccessibleContextassociated with thisChoice. ForChoicecomponents, theAccessibleContexttakes the form of anAccessibleAWTChoice. A newAccessibleAWTChoiceinstance is created if necessary.- Specified by:
getAccessibleContextin interfaceAccessible- Overrides:
getAccessibleContextin classComponent- Returns:
- an
AccessibleAWTChoicethat serves as theAccessibleContextof thisChoice - Since:
- 1.3
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