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JavaTM 2 Platform Std. Ed. v1.3.1 |
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java.lang.Object | +--java.awt.Component | +--java.awt.Choice
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.
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.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
public Choice()
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.
select(int)
,
select(java.lang.String)
Method Detail |
public void addNotify()
addNotify
in class Component
Toolkit.createChoice(java.awt.Choice)
,
Component.getToolkit()
public int getItemCount()
Choice
menu.getItem(int)
public int countItems()
getItemCount()
.
public String getItem(int index)
Choice
menu.index
- the index at which to begin.getItemCount()
public void add(String item)
Choice
menu.item
- the item to be addedNullPointerException
- if the item's value is null
.public void addItem(String item)
item
- the item to be addedNullPointerException
- If the item's value is equal to null.public void insert(String item, int index)
item
- the item to be insertedindex
- the position at which the item should be insertedIllegalArgumentException
- if index is less than 0.public void remove(String item)
item
from the Choice
menu.item
- the item to remove from this Choice
menu.IllegalArgumentException
- if the item doesn't
exist in the choice menu.public void remove(int position)
position
- the position of the item.public void removeAll()
remove(java.lang.String)
public String getSelectedItem()
getSelectedIndex()
public Object[] getSelectedObjects()
getSelectedObjects
in interface ItemSelectable
ItemSelectable
public int getSelectedIndex()
getSelectedItem()
public void select(int pos)
Choice
menu to be the
item at the specified position.pos
- the positon of the selected item.IllegalArgumentException
- if the specified
position is invalid.getSelectedItem()
,
getSelectedIndex()
public 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.str
- the specified stringgetSelectedItem()
,
getSelectedIndex()
public void addItemListener(ItemListener l)
Choice
menu.
If l is null, no exception is thrown and no action is performed.addItemListener
in interface ItemSelectable
l
- the item listener.ItemEvent
,
ItemListener
,
removeItemListener(java.awt.event.ItemListener)
public void removeItemListener(ItemListener l)
Choice
menu.
If l is null, no exception is thrown and no action is performed.removeItemListener
in interface ItemSelectable
l
- the item listener.ItemEvent
,
ItemListener
,
addItemListener(java.awt.event.ItemListener)
public EventListener[] getListeners(Class listenerType)
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.
getListeners
in class Component
listenerType
- Type of listeners requestedprotected void processEvent(AWTEvent e)
ItemEvent
, it invokes the
processItemEvent
method. Otherwise, it calls its
superclass's processEvent
method.processEvent
in class Component
e
- the event.ItemEvent
,
processItemEvent(java.awt.event.ItemEvent)
protected 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
.
e
- the item event.ItemEvent
,
ItemListener
,
addItemListener(java.awt.event.ItemListener)
,
Component.enableEvents(long)
protected String paramString()
paramString
in class Component
Choice
menu.public AccessibleContext getAccessibleContext()
getAccessibleContext
in interface Accessible
getAccessibleContext
in class Component
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JavaTM 2 Platform Std. Ed. v1.3.1 |
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