java.awt
Class List

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.List

All Implemented Interfaces:

Accessible, ImageObserver, ItemSelectable, MenuContainer, Serializable

public class List

extends Component

implements ItemSelectable, Accessible

The 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:

Clicking on an item that isn't selected selects it. 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. Selecting an item causes any other selected item to be automatically deselected.

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, 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, 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:

JDK1.0

See Also:

ItemEvent, ItemListener, ActionEvent, ActionListener, Serialized Form

Inner Class Summary

protected class

List.AccessibleAWTList This class implements accessibility support for the List 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

List()
Creates a new scrolling list.

List(int rows)
Creates a new scrolling list initialized with the specified number of visible lines.

List(int rows, boolean multipleMode)
Creates a new scrolling list initialized to display the specified number of rows.

Method Summary

void	add(String item) Adds the specified item to the end of scrolling list.
void	add(String item, int index) Adds the specified item to the the scrolling list at the position indicated by the index.
void	addActionListener(ActionListener l) Adds the specified action listener to receive action events from this list.
void	addItem(String item) Deprecated. replaced by add(String).
void	addItem(String item, int index) Deprecated. replaced by add(String, int).
void	addItemListener(ItemListener l) Adds the specified item listener to receive item events from this list.
void	addNotify() Creates the peer for the list.
boolean	allowsMultipleSelections() Deprecated. As of JDK version 1.1, replaced by isMultipleMode().
void	clear() Deprecated. As of JDK version 1.1, replaced by removeAll().
int	countItems() Deprecated. As of JDK version 1.1, replaced by getItemCount().
void	delItem(int position) Deprecated. replaced by remove(String) and remove(int).
void	delItems(int start, int end) 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.
void	deselect(int index) Deselects the item at the specified index.
AccessibleContext	getAccessibleContext() Gets the AccessibleContext associated with this List.
String	getItem(int index) Gets the item associated with the specified index.
int	getItemCount() Gets the number of items in the list.
String[]	getItems() Gets the items in the list.
EventListener[]	getListeners(Class listenerType) Return an array of all the listeners that were added to the List with addXXXListener(), where XXX is the name of the listenerType argument.
Dimension	getMinimumSize() Determines the minimum size of this scrolling list.
Dimension	getMinimumSize(int rows) Gets the minumum dimensions for a list with the specified number of rows.
Dimension	getPreferredSize() Gets the preferred size of this scrolling list.
Dimension	getPreferredSize(int rows) Gets the preferred dimensions for a list with the specified number of rows.
int	getRows() Get the number of visible lines in this list.
int	getSelectedIndex() Gets the index of the selected item on the list,
int[]	getSelectedIndexes() Gets the selected indexes on the list.
String	getSelectedItem() Get the selected item on this scrolling list.
String[]	getSelectedItems() Get the selected items on this scrolling list.
Object[]	getSelectedObjects() Returns the selected items on the list in an array of Objects.
int	getVisibleIndex() Gets the index of the item that was last made visible by the method makeVisible.
boolean	isIndexSelected(int index) Determines if the specified item in this scrolling list is selected.
boolean	isMultipleMode() Determines whether this list allows multiple selections.
boolean	isSelected(int index) Deprecated. As of JDK version 1.1, replaced by isIndexSelected(int).
void	makeVisible(int index) Makes the item at the specified index visible.
Dimension	minimumSize() Deprecated. As of JDK version 1.1, replaced by getMinimumSize().
Dimension	minimumSize(int rows) Deprecated. As of JDK version 1.1, replaced by getMinimumSize(int).
protected String	paramString() Returns the parameter string representing the state of this scrolling list.
Dimension	preferredSize() Deprecated. As of JDK version 1.1, replaced by getPreferredSize().
Dimension	preferredSize(int rows) Deprecated. As of JDK version 1.1, replaced by getPreferredSize(int).
protected void	processActionEvent(ActionEvent e) Processes action events occurring on this component by dispatching them to any registered ActionListener objects.
protected void	processEvent(AWTEvent e) Processes events on this scrolling list.
protected void	processItemEvent(ItemEvent e) Processes item events occurring on this list by dispatching them to any registered ItemListener objects.
void	remove(int position) Remove the item at the specified position from this scrolling list.
void	remove(String item) Removes the first occurrence of an item from the list.
void	removeActionListener(ActionListener l) Removes the specified action listener so that it no longer receives action events from this list.
void	removeAll() Removes all items from this list.
void	removeItemListener(ItemListener l) Removes the specified item listener so that it no longer receives item events from this list.
void	removeNotify() 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 by setMultipleMode(boolean).

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, getName, getParent, getPeer, 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, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, postEvent, prepareImage, prepareImage, print, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, 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

List

public List()

Creates a new scrolling list. By default, there are four visible lines and multiple selections are not allowed.

List

public List(int rows)

Creates a new scrolling list initialized with the specified number of visible lines. By default, multiple selections are not allowed.

Parameters:

rows - the number of items to show.

Since:

JDK1.1

List

public List(int rows,
            boolean multipleMode)

Creates a new scrolling list initialized to display the specified number of rows. If the value of multipleMode is true, then the user can select multiple items from the list. If it is false, only one item at a time can be selected.

Parameters:

rows - the number of items to show.

multipleMode - if true, then multiple selections are allowed; otherwise, only one item can be selected at a time.

Method Detail

addNotify

public void addNotify()

Creates the peer for the list. The peer allows us to modify the list's appearance without changing its functionality.

Overrides:

addNotify in class Component

Following copied from class: java.awt.Component

See Also:

Component.isDisplayable(), Component.removeNotify()

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 class Component

Following copied from class: java.awt.Component

See Also:

Component.isDisplayable(), Component.addNotify()

getItemCount

public int getItemCount()

Gets the number of items in the list.

Returns:

the number of items in the list.

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 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:

getItemCount()

getItems

public String[] getItems()

Gets the items in the list.

Returns:

a string array containing items of the list.

Since:

JDK1.1

See Also:

select(int), deselect(int), isIndexSelected(int)

add

public void add(String item)

Adds the specified item to the end of scrolling list.

Parameters:

item - the item to be added.

Since:

JDK1.1

addItem

public void addItem(String item)

Deprecated. replaced by add(String).

add

public void add(String item,
                int index)

Adds the specified item to the 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 is null then the item is treated as an empty string, "".

index - the position at which to add the item.

Since:

JDK1.1

addItem

public void addItem(String item,
                    int index)

Deprecated. replaced by add(String, int).

replaceItem

public void replaceItem(String newValue,
                        int index)

Replaces the item at the specified index in the scrolling list with the new string.

Parameters:

newValue - a new string to replace an existing item.

index - the position of the item to replace.

removeAll

public void removeAll()

Removes all items from this list.

Since:

JDK1.1

See Also:

remove(java.lang.String), delItems(int, int)

clear

public void clear()

Deprecated. As of JDK version 1.1, replaced by removeAll().

remove

public void remove(String item)

Removes the first occurrence of an item from the list.

Parameters:

item - the item to remove from the list.

Throws:

IllegalArgumentException - if the item doesn't exist in the list.

Since:

JDK1.1

remove

public void remove(int position)

Remove the item at the specified position from this scrolling list.

Parameters:

position - the index of the item to delete.

Throws:

ArrayIndexOutOfBoundsException - if the position is less than 0 or greater than getItemCount()-1

Since:

JDK1.1

See Also:

add(String, int)

delItem

public void delItem(int position)

Deprecated. replaced by remove(String) and remove(int).

getSelectedIndex

public int getSelectedIndex()

Gets the index of the selected item on the list,

Returns:

the index of the selected item, or -1 if no item is selected, or if more that one item is selected.

See Also:

select(int), deselect(int), isIndexSelected(int)

getSelectedIndexes

public int[] getSelectedIndexes()

Gets the selected indexes on the list.

Returns:

an array of the selected indexes of this scrolling list. If no items are selected, a zero-length array is returned.

See Also:

select(int), deselect(int), isIndexSelected(int)

getSelectedItem

public String getSelectedItem()

Get the selected item on this scrolling list.

Returns:

the selected item on the list, or null if no item is selected.

See Also:

select(int), deselect(int), isIndexSelected(int)

getSelectedItems

public String[] getSelectedItems()

Get the selected items on this scrolling list.

Returns:

an array of the selected items on this scrolling list.

See Also:

select(int), deselect(int), isIndexSelected(int)

getSelectedObjects

public Object[] getSelectedObjects()

Returns the selected items on the list in an array of Objects.

Specified by:

getSelectedObjects in interface ItemSelectable

See Also:

ItemSelectable

select

public void select(int index)

Selects the item at the specified index in the scrolling list.

Parameters:

index - the position of the item to select.

See Also:

getSelectedItem(), deselect(int), isIndexSelected(int)

deselect

public void deselect(int index)

Deselects the item at the specified index.

If the item at the specified index is not selected, or if the index is out of range, then the operation is ignored.

Parameters:

index - the position of the item to deselect.

See Also:

select(int), getSelectedItem(), isIndexSelected(int)

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:

JDK1.1

See Also:

select(int), deselect(int)

isSelected

public boolean isSelected(int index)

Deprecated. As of JDK version 1.1, replaced by isIndexSelected(int).

getRows

public int getRows()

Get the number of visible lines in this list.

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:

JDK1.1

See Also:

setMultipleMode(boolean)

allowsMultipleSelections

public boolean allowsMultipleSelections()

Deprecated. As of JDK version 1.1, replaced by isMultipleMode().

setMultipleMode

public void setMultipleMode(boolean b)

Sets the flag that determines whether this list allows multiple selections.

Parameters:

b - if true then multiple selections are allowed; otherwise, only one item from the list can be selected at once.

Since:

JDK1.1

See Also:

isMultipleMode()

setMultipleSelections

public void setMultipleSelections(boolean b)

Deprecated. As of JDK version 1.1, replaced by setMultipleMode(boolean).

getVisibleIndex

public int getVisibleIndex()

Gets the index of the item that was last made visible by the method makeVisible.

Returns:

the index of the item that was last made visible.

See Also:

makeVisible(int)

makeVisible

public void makeVisible(int index)

Makes the item at the specified index visible.

Parameters:

index - the position of the item.

See Also:

getVisibleIndex()

getPreferredSize

public Dimension getPreferredSize(int rows)

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:

JDK1.1

See Also:

Component.getPreferredSize()

preferredSize

public Dimension preferredSize(int rows)

Deprecated. As of JDK version 1.1, replaced by getPreferredSize(int).

getPreferredSize

public Dimension getPreferredSize()

Gets the preferred size of this scrolling list.

Overrides:

getPreferredSize in class Component

Returns:

the preferred dimensions for displaying this scrolling list.

Since:

JDK1.1

See Also:

Component.getPreferredSize()

preferredSize

public Dimension preferredSize()

Deprecated. As of JDK version 1.1, replaced by getPreferredSize().

Overrides:

preferredSize in class Component

getMinimumSize

public Dimension getMinimumSize(int rows)

Gets the minumum 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:

JDK1.1

See Also:

Component.getMinimumSize()

minimumSize

public Dimension minimumSize(int rows)

Deprecated. As of JDK version 1.1, replaced by getMinimumSize(int).

getMinimumSize

public Dimension getMinimumSize()

Determines the minimum size of this scrolling list.

Overrides:

getMinimumSize in class Component

Returns:

the minimum dimensions needed to display this scrolling list.

Since:

JDK1.1

See Also:

Component.getMinimumSize()

minimumSize

public Dimension minimumSize()

Deprecated. As of JDK version 1.1, replaced by getMinimumSize().

Overrides:

minimumSize in class Component

addItemListener

public void addItemListener(ItemListener l)

Adds the specified item listener to receive item events from this list. 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 list. 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)

addActionListener

public void addActionListener(ActionListener l)

Adds the specified action listener to receive action events from this list. Action events occur when a user double-clicks on a list item. If l is null, no exception is thrown and no action is performed.

Parameters:

l - the action listener.

Since:

JDK1.1

See Also:

ActionEvent, ActionListener, removeActionListener(java.awt.event.ActionListener)

removeActionListener

public void removeActionListener(ActionListener l)

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 l is null, no exception is thrown and no action is performed.

Parameters:

l - the action listener.

Since:

JDK1.1

See Also:

ActionEvent, ActionListener, addActionListener(java.awt.event.ActionListener)

getListeners

public EventListener[] getListeners(Class listenerType)

Return an array of all the listeners that were added to the List with addXXXListener(), where XXX is the name of the listenerType argument. For example, to get all of the ItemListener(s) for the given List l, one would write:

 ItemListener[] ils = (ItemListener[])(l.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 list

Since:

1.3

processEvent

protected void processEvent(AWTEvent e)

Processes events on this scrolling list. If an event is an instance of ItemEvent, it invokes the processItemEvent method. Else, if the event is an instance of ActionEvent, it invokes processActionEvent. If the event is not an item event or an action event, it invokes processEvent on the superclass.

Overrides:

processEvent in class Component

Parameters:

e - the event.

Since:

JDK1.1

See Also:

ActionEvent, ItemEvent, processActionEvent(java.awt.event.ActionEvent), processItemEvent(java.awt.event.ItemEvent)

processItemEvent

protected void processItemEvent(ItemEvent e)

Processes item events occurring on this list 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:

• An ItemListener object is registered via addItemListener.
• Item events are enabled via enableEvents.

Parameters:

e - the item event.

Since:

JDK1.1

See Also:

ItemEvent, ItemListener, addItemListener(java.awt.event.ItemListener), Component.enableEvents(long)

processActionEvent

protected void processActionEvent(ActionEvent e)

Processes action events occurring on this component by dispatching them to any registered ActionListener 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 via addActionListener.
• Action events are enabled via enableEvents.

Parameters:

e - the action event.

Since:

JDK1.1

See Also:

ActionEvent, ActionListener, addActionListener(java.awt.event.ActionListener), Component.enableEvents(long)

paramString

protected String paramString()

Returns the parameter string representing the state of this scrolling list. This string is useful for debugging.

Overrides:

paramString in class Component

Returns:

the parameter string of this scrolling list.

delItems

public void delItems(int start,
                     int end)

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.

getAccessibleContext

public AccessibleContext getAccessibleContext()

Gets the AccessibleContext associated with this List. For lists, the AccessibleContext takes the form of an AccessibleAWTList. A new AccessibleAWTList instance is created if necessary.

Specified by:

getAccessibleContext in interface Accessible

Overrides:

getAccessibleContext in class Component

Returns:

an AccessibleAWTList that serves as the AccessibleContext of this List