Class List
- All Implemented Interfaces:
ImageObserver
,ItemSelectable
,MenuContainer
,Serializable
,Accessible
List
component presents the user with a
scrolling list of text items. The list can be set up so that
the user can choose either one item or multiple items.
For example, the code . . .
List lst = new List(4, false); lst.add("Mercury"); lst.add("Venus"); lst.add("Earth"); lst.add("JavaSoft"); lst.add("Mars"); lst.add("Jupiter"); lst.add("Saturn"); lst.add("Uranus"); lst.add("Neptune"); lst.add("Pluto"); cnt.add(lst);
where cnt
is a container, produces the following
scrolling list:
If the List allows multiple selections, then clicking on
an item that is already selected deselects it. In the preceding
example, only one item from the scrolling list can be selected
at a time, since the second argument when creating the new scrolling
list is false
. If the List does not allow multiple
selections, selecting an item causes any other selected item
to be deselected.
Note that the list in the example shown was created with four visible
rows. Once the list has been created, the number of visible rows
cannot be changed. A default List
is created with
four rows, so that lst = new List()
is equivalent to
list = new List(4, false)
.
Beginning with Java 1.1, the Abstract Window Toolkit
sends the List
object all mouse, keyboard, and focus events
that occur over it. (The old AWT event model is being maintained
only for backwards compatibility, and its use is discouraged.)
When an item is selected or deselected by the user, AWT sends an instance
of ItemEvent
to the list.
When the user double-clicks on an item in a scrolling list,
AWT sends an instance of ActionEvent
to the
list following the item event. AWT also generates an action event
when the user presses the return key while an item in the
list is selected.
If an application wants to perform some action based on an item
in this list being selected or activated by the user, it should implement
ItemListener
or ActionListener
as appropriate and register the new listener to receive
events from this list.
For multiple-selection scrolling lists, it is considered a better user interface to use an external gesture (such as clicking on a button) to trigger the action.
- Since:
- 1.0
- See Also:
-
Nested Class Summary
Modifier and TypeClassDescriptionprotected class
This class implements accessibility support for theList
class.Nested classes/interfaces declared in class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
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Field Summary
Fields declared in class java.awt.Component
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
Fields declared in interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
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Constructor Summary
-
Method Summary
Modifier and TypeMethodDescriptionvoid
Adds the specified item to the end of scrolling list.void
Adds the specified item to the scrolling list at the position indicated by the index.void
Adds the specified action listener to receive action events from this list.void
Deprecated.void
Deprecated.replaced byadd(String, int)
.void
Adds the specified item listener to receive item events from this list.void
Creates the peer for the list.boolean
Deprecated.As of JDK version 1.1, replaced byisMultipleMode()
.void
clear()
Deprecated.As of JDK version 1.1, replaced byremoveAll()
.int
Deprecated.As of JDK version 1.1, replaced bygetItemCount()
.void
delItem
(int position) Deprecated.replaced byremove(String)
andremove(int)
.void
delItems
(int start, int end) Deprecated.As of JDK version 1.1, Not for public use in the future.void
deselect
(int index) Deselects the item at the specified index.Gets theAccessibleContext
associated with thisList
.Returns an array of all the action listeners registered on this list.getItem
(int index) Gets the item associated with the specified index.int
Gets the number of items in the list.Returns an array of all the item listeners registered on this list.String[]
getItems()
Gets the items in the list.<T extends EventListener>
T[]getListeners
(Class<T> listenerType) Returns an array of all the objects currently registered asFooListener
s upon thisList
.Determines the minimum size of this scrolling list.getMinimumSize
(int rows) Gets the minimum dimensions for a list with the specified number of rows.Gets the preferred size of this scrolling list.getPreferredSize
(int rows) Gets the preferred dimensions for a list with the specified number of rows.int
getRows()
Gets the number of visible lines in this list.int
Gets the index of the selected item on the list,int[]
Gets the selected indexes on the list.Gets the selected item on this scrolling list.String[]
Gets the selected items on this scrolling list.Object[]
Gets the selected items on this scrolling list in an array of Objects.int
Gets the index of the item that was last made visible by the methodmakeVisible
.boolean
isIndexSelected
(int index) Determines if the specified item in this scrolling list is selected.boolean
Determines whether this list allows multiple selections.boolean
isSelected
(int index) Deprecated.As of JDK version 1.1, replaced byisIndexSelected(int)
.void
makeVisible
(int index) Makes the item at the specified index visible.Deprecated.As of JDK version 1.1, replaced bygetMinimumSize()
.minimumSize
(int rows) Deprecated.As of JDK version 1.1, replaced bygetMinimumSize(int)
.protected String
Returns the parameter string representing the state of this scrolling list.Deprecated.As of JDK version 1.1, replaced bygetPreferredSize()
.preferredSize
(int rows) Deprecated.As of JDK version 1.1, replaced bygetPreferredSize(int)
.protected void
Processes action events occurring on this component by dispatching them to any registeredActionListener
objects.protected void
Processes events on this scrolling list.protected void
Processes item events occurring on this list by dispatching them to any registeredItemListener
objects.void
remove
(int position) Removes the item at the specified position from this scrolling list.void
Removes the first occurrence of an item from the list.void
Removes the specified action listener so that it no longer receives action events from this list.void
Removes all items from this list.void
Removes the specified item listener so that it no longer receives item events from this list.void
Removes the peer for this list.void
replaceItem
(String newValue, int index) Replaces the item at the specified index in the scrolling list with the new string.void
select
(int index) Selects the item at the specified index in the scrolling list.void
setMultipleMode
(boolean b) Sets the flag that determines whether this list allows multiple selections.void
setMultipleSelections
(boolean b) Deprecated.As of JDK version 1.1, replaced bysetMultipleMode(boolean)
.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, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, 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, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, postEvent, prepareImage, prepareImage, print, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, 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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List
Creates a new scrolling list. By default, there are four visible lines and multiple selections are not allowed. Note that this is a convenience method forList(0, false)
. Also note that the number of visible lines in the list cannot be changed after it has been created.- Throws:
HeadlessException
- if GraphicsEnvironment.isHeadless() returns true.- See Also:
-
List
Creates a new scrolling list initialized with the specified number of visible lines. By default, multiple selections are not allowed. Note that this is a convenience method forList(rows, false)
. Also note that the number of visible rows in the list cannot be changed after it has been created.- Parameters:
rows
- the number of items to show.- Throws:
HeadlessException
- if GraphicsEnvironment.isHeadless() returns true.- Since:
- 1.1
- See Also:
-
List
Creates a new scrolling list initialized to display the specified number of rows. Note that if zero rows are specified, then the list will be created with a default of four rows. Also note that the number of visible rows in the list cannot be changed after it has been created. If the value ofmultipleMode
istrue
, then the user can select multiple items from the list. If it isfalse
, only one item at a time can be selected.- Parameters:
rows
- the number of items to show.multipleMode
- iftrue
, then multiple selections are allowed; otherwise, only one item can be selected at a time.- Throws:
HeadlessException
- if GraphicsEnvironment.isHeadless() returns true.- See Also:
-
-
Method Details
-
addNotify
-
removeNotify
public void removeNotify()Removes the peer for this list. The peer allows us to modify the list's appearance without changing its functionality.- Overrides:
removeNotify
in classComponent
- See Also:
-
getItemCount
public int getItemCount()Gets the number of items in the list.- Returns:
- the number of items in the list
- Since:
- 1.1
- See Also:
-
countItems
Deprecated.As of JDK version 1.1, replaced bygetItemCount()
.Returns the number of items in the list.- Returns:
- the number of items in the list
-
getItem
Gets the item associated with the specified index.- Parameters:
index
- the position of the item- Returns:
- an item that is associated with the specified index
- See Also:
-
getItems
Gets the items in the list.- Returns:
- a string array containing items of the list
- Since:
- 1.1
- See Also:
-
add
Adds the specified item to the end of scrolling list.- Parameters:
item
- the item to be added- Since:
- 1.1
-
addItem
Deprecated.replaced byadd(String)
.Adds the specified item to the end of the list.- Parameters:
item
- the item to be added
-
add
Adds the specified item to the scrolling list at the position indicated by the index. The index is zero-based. If the value of the index is less than zero, or if the value of the index is greater than or equal to the number of items in the list, then the item is added to the end of the list.- Parameters:
item
- the item to be added; if this parameter isnull
then the item is treated as an empty string,""
index
- the position at which to add the item- Since:
- 1.1
-
addItem
Deprecated.replaced byadd(String, int)
.Adds the specified item to the list at the position indicated by the index.- Parameters:
item
- the item to be addedindex
- the position at which to add the item
-
replaceItem
Replaces the item at the specified index in the scrolling list with the new string.- Parameters:
newValue
- a new string to replace an existing itemindex
- the position of the item to replace- Throws:
ArrayIndexOutOfBoundsException
- ifindex
is out of range
-
removeAll
public void removeAll()Removes all items from this list.- Since:
- 1.1
- See Also:
-
clear
Deprecated.As of JDK version 1.1, replaced byremoveAll()
. -
remove
Removes the first occurrence of an item from the list. If the specified item is selected, and is the only selected item in the list, the list is set to have no selection.- Parameters:
item
- the item to remove from the list- Throws:
IllegalArgumentException
- if the item doesn't exist in the list- Since:
- 1.1
-
remove
public void remove(int position) Removes the item at the specified position from this scrolling list. If the item with the specified position is selected, and is the only selected item in the list, the list is set to have no selection.- Parameters:
position
- the index of the item to delete- Throws:
ArrayIndexOutOfBoundsException
- if theposition
is less than 0 or greater thangetItemCount()-1
- Since:
- 1.1
- See Also:
-
delItem
Deprecated.replaced byremove(String)
andremove(int)
.Removes the item at the specified position.- Parameters:
position
- the index of the item to delete
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getSelectedIndex
public int getSelectedIndex()Gets the index of the selected item on the list,- Returns:
- the index of the selected item;
if no item is selected, or if multiple items are
selected,
-1
is returned. - See Also:
-
getSelectedIndexes
public int[] getSelectedIndexes()Gets the selected indexes on the list.- Returns:
- an array of the selected indexes on this scrolling list; if no item is selected, a zero-length array is returned.
- See Also:
-
getSelectedItem
Gets the selected item on this scrolling list.- Returns:
- the selected item on the list;
if no item is selected, or if multiple items are
selected,
null
is returned. - See Also:
-
getSelectedItems
Gets the selected items on this scrolling list.- Returns:
- an array of the selected items on this scrolling list; if no item is selected, a zero-length array is returned.
- See Also:
-
getSelectedObjects
Gets the selected items on this scrolling list in an array of Objects.- Specified by:
getSelectedObjects
in interfaceItemSelectable
- Returns:
- an array of
Object
s representing the selected items on this scrolling list; if no item is selected, a zero-length array is returned. - See Also:
-
select
public void select(int index) Selects the item at the specified index in the scrolling list.Note that passing out of range parameters is invalid, and will result in unspecified behavior.
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:
index
- the position of the item to select- See Also:
-
deselect
public void deselect(int index) Deselects the item at the specified index.Note that passing out of range parameters is invalid, and will result in unspecified behavior.
If the item at the specified index is not selected, then the operation is ignored.
- Parameters:
index
- the position of the item to deselect- See Also:
-
isIndexSelected
public boolean isIndexSelected(int index) Determines if the specified item in this scrolling list is selected.- Parameters:
index
- the item to be checked- Returns:
true
if the specified item has been selected;false
otherwise- Since:
- 1.1
- See Also:
-
isSelected
Deprecated.As of JDK version 1.1, replaced byisIndexSelected(int)
.Determines if the specified item in the list is selected.- Parameters:
index
- specifies the item to be checked- Returns:
true
if the item is selected; otherwisefalse
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getRows
public int getRows()Gets the number of visible lines in this list. Note that once theList
has been created, this number will never change.- Returns:
- the number of visible lines in this scrolling list
-
isMultipleMode
public boolean isMultipleMode()Determines whether this list allows multiple selections.- Returns:
true
if this list allows multiple selections; otherwise,false
- Since:
- 1.1
- See Also:
-
allowsMultipleSelections
Deprecated.As of JDK version 1.1, replaced byisMultipleMode()
.Determines whether this list allows multiple selections.- Returns:
true
if this list allows multiple selections; otherwisefalse
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setMultipleMode
public void setMultipleMode(boolean b) Sets the flag that determines whether this list allows multiple selections. When the selection mode is changed from multiple-selection to single-selection, the selected items change as follows: If a selected item has the location cursor, only that item will remain selected. If no selected item has the location cursor, all items will be deselected.- Parameters:
b
- iftrue
then multiple selections are allowed; otherwise, only one item from the list can be selected at once- Since:
- 1.1
- See Also:
-
setMultipleSelections
Deprecated.As of JDK version 1.1, replaced bysetMultipleMode(boolean)
.Enables or disables multiple selection mode for this list.- Parameters:
b
-true
to enable multiple mode,false
otherwise
-
getVisibleIndex
public int getVisibleIndex()Gets the index of the item that was last made visible by the methodmakeVisible
.- Returns:
- the index of the item that was last made visible
- See Also:
-
makeVisible
public void makeVisible(int index) Makes the item at the specified index visible.- Parameters:
index
- the position of the item- See Also:
-
getPreferredSize
Gets the preferred dimensions for a list with the specified number of rows.- Parameters:
rows
- number of rows in the list- Returns:
- the preferred dimensions for displaying this scrolling list given that the specified number of rows must be visible
- Since:
- 1.1
- See Also:
-
preferredSize
Deprecated.As of JDK version 1.1, replaced bygetPreferredSize(int)
.Returns the preferred size of this component assuming it has the specified number of rows.- Parameters:
rows
- the number of rows- Returns:
- the preferred dimensions for displaying this list
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getPreferredSize
Gets the preferred size of this scrolling list.- Overrides:
getPreferredSize
in classComponent
- Returns:
- the preferred dimensions for displaying this scrolling list
- Since:
- 1.1
- See Also:
-
preferredSize
Deprecated.As of JDK version 1.1, replaced bygetPreferredSize()
.Description copied from class:Component
Returns the component's preferred size.- Overrides:
preferredSize
in classComponent
- Returns:
- the component's preferred size
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getMinimumSize
Gets the minimum dimensions for a list with the specified number of rows.- Parameters:
rows
- number of rows in the list- Returns:
- the minimum dimensions for displaying this scrolling list given that the specified number of rows must be visible
- Since:
- 1.1
- See Also:
-
minimumSize
Deprecated.As of JDK version 1.1, replaced bygetMinimumSize(int)
.Returns the minimum dimensions for the list with the specified number of rows.- Parameters:
rows
- the number of rows in the list- Returns:
- the minimum dimensions for displaying this list
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getMinimumSize
Determines the minimum size of this scrolling list.- Overrides:
getMinimumSize
in classComponent
- Returns:
- the minimum dimensions needed to display this scrolling list
- Since:
- 1.1
- See Also:
-
minimumSize
Deprecated.As of JDK version 1.1, replaced bygetMinimumSize()
.Description copied from class:Component
Returns the minimum size of this component.- Overrides:
minimumSize
in classComponent
- Returns:
- the minimum size of this component
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addItemListener
Adds the specified item listener to receive item events from this list. Item events are sent in response to user input, but not in response to calls toselect
ordeselect
. If listenerl
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 this list. If listenerl
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 list.- Returns:
- all of this list's
ItemListener
s or an empty array if no item listeners are currently registered - Since:
- 1.4
- See Also:
-
addActionListener
Adds the specified action listener to receive action events from this list. Action events occur when a user double-clicks on a list item or types Enter when the list has the keyboard focus.If listener
l
isnull
, no exception is thrown and no action is performed.Refer to AWT Threading Issues for details on AWT's threading model.
- Parameters:
l
- the action listener- Since:
- 1.1
- See Also:
-
removeActionListener
Removes the specified action listener so that it no longer receives action events from this list. Action events occur when a user double-clicks on a list item. If listenerl
isnull
, no exception is thrown and no action is performed.Refer to AWT Threading Issues for details on AWT's threading model.
- Parameters:
l
- the action listener- Since:
- 1.1
- See Also:
-
getActionListeners
Returns an array of all the action listeners registered on this list.- Returns:
- all of this list's
ActionListener
s or an empty array if no action listeners are currently registered - Since:
- 1.4
- See Also:
-
getListeners
Returns an array of all the objects currently registered asFooListener
s upon thisList
.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 aList l
for its item listeners with the following code:ItemListener[] ils = (ItemListener[])(l.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 list, 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 scrolling list. If an event is an instance ofItemEvent
, it invokes theprocessItemEvent
method. Else, if the event is an instance ofActionEvent
, it invokesprocessActionEvent
. If the event is not an item event or an action event, it invokesprocessEvent
on the superclass.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 this list 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
-
processActionEvent
Processes action events occurring on this component by dispatching them to any registeredActionListener
objects.This method is not called unless action events are enabled for this component. Action events are enabled when one of the following occurs:
- An
ActionListener
object is registered viaaddActionListener
. - Action 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 action event- Since:
- 1.1
- See Also:
- An
-
paramString
Returns the parameter string representing the state of this scrolling list. This string is useful for debugging.- Overrides:
paramString
in classComponent
- Returns:
- the parameter string of this scrolling list
-
delItems
Deprecated.As of JDK version 1.1, Not for public use in the future. This method is expected to be retained only as a package private method.Deletes the list items in the specified index range.- Parameters:
start
- the beginning index of the range to deleteend
- the ending index of the range to delete
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getAccessibleContext
Gets theAccessibleContext
associated with thisList
. For lists, theAccessibleContext
takes the form of anAccessibleAWTList
. A newAccessibleAWTList
instance is created, if necessary.- Specified by:
getAccessibleContext
in interfaceAccessible
- Overrides:
getAccessibleContext
in classComponent
- Returns:
- an
AccessibleAWTList
that serves as theAccessibleContext
of thisList
- Since:
- 1.3
-
add(String)
.