JavaTM 2 Platform
Std. Ed. v1.3.1

java.awt
Class Choice

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.Choice
All Implemented Interfaces:
Accessible, ImageObserver, ItemSelectable, MenuContainer, Serializable

public class Choice
extends Component
implements ItemSelectable, Accessible

The 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:
JDK1.0
See Also:
Serialized Form

Inner Class Summary
protected  class Choice.AccessibleAWTChoice
          This class implements accessibility support for the Choice class.
 
Inner classes inherited from class java.awt.Component
Component.AccessibleAWTComponent
 
Fields inherited from class java.awt.Component
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
 
Constructor Summary
Choice()
          Creates a new choice menu.
 
Method Summary
 void add(String item)
          Adds an item to this Choice menu.
 void addItem(String item)
          Adds an item to this Choice.
 void addItemListener(ItemListener l)
          Adds the specified item listener to receive item events from this Choice menu.
 void addNotify()
          Creates the Choice's peer.
 int countItems()
          Deprecated. As of JDK version 1.1, replaced by getItemCount().
 AccessibleContext getAccessibleContext()
          Gets the AccessibleContext associated with this Choice.
 String getItem(int index)
          Gets the string at the specified index in this Choice menu.
 int getItemCount()
          Returns the number of items in this Choice menu.
 EventListener[] getListeners(Class listenerType)
          Return an array of all the listeners that were added to the Choice with addXXXListener(), where XXX is the name of the listenerType argument.
 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(String item, int index)
          Inserts the item into this choice at the specified position.
protected  String paramString()
          Returns the parameter string representing the state of this choice menu.
protected  void processEvent(AWTEvent e)
          Processes events on this choice.
protected  void processItemEvent(ItemEvent e)
          Processes item events occurring on this Choice menu by dispatching them to any registered ItemListener objects.
 void remove(int position)
          Removes an item from the choice menu at the specified position.
 void remove(String item)
          Remove the first occurrence of item from the Choice menu.
 void removeAll()
          Removes all items from the choice menu.
 void removeItemListener(ItemListener l)
          Removes the specified item listener so that it no longer receives item events from this Choice menu.
 void select(int pos)
          Sets the selected item in this Choice menu to be the item at the specified position.
 void select(String str)
          Sets the selected item in this Choice 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, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentOrientation, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getInputContext, getInputMethodRequests, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getName, getParent, getPeer, getPreferredSize, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isDisplayable, isDoubleBuffered, isEnabled, isFocusTraversable, isLightweight, isOpaque, 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, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFont, setForeground, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, show, size, toString, transferFocus, update, validate
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

Choice

public 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.

See Also:
select(int), select(java.lang.String)
Method Detail

addNotify

public void addNotify()
Creates the Choice's peer. This peer allows us to change the look of the Choice without changing its functionality.
Overrides:
addNotify in class Component
See Also:
Toolkit.createChoice(java.awt.Choice), Component.getToolkit()

getItemCount

public int getItemCount()
Returns the number of items in this Choice menu.
Since:
JDK1.1
See Also:
getItem(int)

countItems

public int countItems()
Deprecated. As of JDK version 1.1, replaced by getItemCount().


getItem

public String getItem(int index)
Gets the string at the specified index in this Choice menu.
Parameters:
index - the index at which to begin.
See Also:
getItemCount()

add

public void add(String item)
Adds an item to this Choice menu.
Parameters:
item - the item to be added
Throws:
NullPointerException - if the item's value is null.
Since:
JDK1.1

addItem

public void addItem(String item)
Adds an item to this Choice.
Parameters:
item - the item to be added
Throws:
NullPointerException - If the item's value is equal to null.

insert

public void insert(String item,
                   int index)
Inserts the item into this choice at the specified position.
Parameters:
item - the item to be inserted
index - the position at which the item should be inserted
Throws:
IllegalArgumentException - if index is less than 0.

remove

public void remove(String item)
Remove the first occurrence of item from the Choice menu.
Parameters:
item - the item to remove from this Choice menu.
Throws:
IllegalArgumentException - if the item doesn't exist in the choice menu.
Since:
JDK1.1

remove

public void remove(int position)
Removes an item from the choice menu at the specified position.
Parameters:
position - the position of the item.
Since:
JDK1.1

removeAll

public void removeAll()
Removes all items from the choice menu.
Since:
JDK1.1
See Also:
remove(java.lang.String)

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()

getSelectedObjects

public Object[] getSelectedObjects()
Returns an array (length 1) containing the currently selected item. If this choice has no items, returns null.
Specified by:
getSelectedObjects in interface ItemSelectable
See Also:
ItemSelectable

getSelectedIndex

public int getSelectedIndex()
Returns the index of the currently selected item.
See Also:
getSelectedItem()

select

public void select(int pos)
Sets the selected item in this Choice menu to be the item at the specified position.
Parameters:
pos - the positon of the selected item.
Throws:
IllegalArgumentException - if the specified position is invalid.
See Also:
getSelectedItem(), getSelectedIndex()

select

public void select(String str)
Sets the selected item in this 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.
Parameters:
str - the specified string
See Also:
getSelectedItem(), getSelectedIndex()

addItemListener

public void addItemListener(ItemListener l)
Adds the specified item listener to receive item events from this Choice menu. If l is null, no exception is thrown and no action is performed.
Specified by:
addItemListener in interface ItemSelectable
Parameters:
l - the item listener.
Since:
JDK1.1
See Also:
ItemEvent, ItemListener, removeItemListener(java.awt.event.ItemListener)

removeItemListener

public void removeItemListener(ItemListener l)
Removes the specified item listener so that it no longer receives item events from this Choice menu. If l is null, no exception is thrown and no action is performed.
Specified by:
removeItemListener in interface ItemSelectable
Parameters:
l - the item listener.
Since:
JDK1.1
See Also:
ItemEvent, ItemListener, addItemListener(java.awt.event.ItemListener)

getListeners

public EventListener[] getListeners(Class listenerType)
Return an array of all the listeners that were added to the Choice with addXXXListener(), where XXX is the name of the listenerType argument. For example, to get all of the ItemListener(s) for the given Choice c, one would write:
 ItemListener[] ils = (ItemListener[])(c.getListeners(ItemListener.class))
 
If no such listener list exists, then an empty array is returned.
Overrides:
getListeners in class Component
Parameters:
listenerType - Type of listeners requested
Returns:
all of the listeners of the specified type supported by this choice
Since:
1.3

processEvent

protected void processEvent(AWTEvent e)
Processes events on this choice. If the event is an instance of ItemEvent, it invokes the processItemEvent method. Otherwise, it calls its superclass's processEvent method.
Overrides:
processEvent in class Component
Parameters:
e - the event.
Since:
JDK1.1
See Also:
ItemEvent, processItemEvent(java.awt.event.ItemEvent)

processItemEvent

protected void processItemEvent(ItemEvent e)
Processes item events occurring on this 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:

Parameters:
e - the item event.
Since:
JDK1.1
See Also:
ItemEvent, ItemListener, addItemListener(java.awt.event.ItemListener), Component.enableEvents(long)

paramString

protected String paramString()
Returns the parameter string representing the state of this choice menu. This string is useful for debugging.
Overrides:
paramString in class Component
Returns:
the parameter string of this Choice menu.

getAccessibleContext

public AccessibleContext getAccessibleContext()
Gets the AccessibleContext associated with this Choice. For Choice components, the AccessibleContext takes the form of an AccessibleAWTChoice. A new AccessibleAWTChoice instance is created if necessary.
Specified by:
getAccessibleContext in interface Accessible
Overrides:
getAccessibleContext in class Component
Returns:
an AccessibleAWTChoice that serves as the AccessibleContext of this Choice

JavaTM 2 Platform
Std. Ed. v1.3.1

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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