Class java.awt.List - JDK 5 Documentation v1.1.8, Java 2 SDK 英文文档

All Packages  Class Hierarchy  This Package  Previous  Next  Index

Class java.awt.List

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

public class List
extends Component
implements ItemSelectable

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.

See Also:: ItemEvent, ItemListener, ActionEvent, ActionListener

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

add(String): Adds the specified item to the end of scrolling list.
add(String, int): Adds the specified item to the end of the scrolling list.
addActionListener(ActionListener): Adds the specified action listener to receive action events from this list.
addItem(String): Adds the specified item to the end of scrolling list.
addItem(String, int): Adds the specified item to the end of the scrolling list.
addItemListener(ItemListener): Adds the specified item listener to receive item events from this list.
addNotify(): Creates the peer for the list.
allowsMultipleSelections(): Deprecated.
clear(): Deprecated.
countItems(): Deprecated.
delItem(int): Removes the item at the specified position from this list.
delItems(int, int): Deprecated.
deselect(int): Deselects the item at the specified index.
getItem(int): Gets the item associated with the specified index.
getItemCount(): Gets the number of items in the list.
getItems(): Gets the items in the list.
getMinimumSize(): Determines the minimum size of this scrolling list.
getMinimumSize(int): Gets the minumum dimensions for a list with the specified number of rows.
getPreferredSize(): Gets the preferred size of this scrolling list.
getPreferredSize(int): Gets the preferred dimensions for a list with the specified number of rows.
getRows(): Get the number of visible lines in this list.
getSelectedIndex(): Gets the index of the selected item on the list,
getSelectedIndexes(): Gets the selected indexes on the list.
getSelectedItem(): Get the selected item on this scrolling list.
getSelectedItems(): Get the selected items on this scrolling list.
getSelectedObjects(): Returns the selected items on the list in an array of Objects.
getVisibleIndex(): Gets the index of the item that was last made visible by the method makeVisible.
isIndexSelected(int): Determines if the specified item in this scrolling list is selected.
isMultipleMode(): Determines whether this list allows multiple selections.
isSelected(int): Deprecated.
makeVisible(int): Makes the item at the specified index visible.
minimumSize(): Deprecated.
minimumSize(int): Deprecated.
paramString(): Returns the parameter string representing the state of this scrolling list.
preferredSize(): Deprecated.
preferredSize(int): Deprecated.
processActionEvent(ActionEvent): Processes action events occurring on this component by dispatching them to any registered ActionListener objects.
processEvent(AWTEvent): Processes events on this scrolling list.
processItemEvent(ItemEvent): Processes item events occurring on this list by dispatching them to any registered ItemListener objects.
remove(int): Remove the item at the specified position from this scrolling list.
remove(String): Removes the first occurrence of an item from the list.
removeActionListener(ActionListener): Removes the specified action listener so that it no longer receives action events from this list.
removeAll(): Removes all items from this list.
removeItemListener(ItemListener): Removes the specified item listener so that it no longer receives item events from this list.
removeNotify(): Removes the peer for this list.
replaceItem(String, int): Replaces the item at the specified index in the scrolling list with the new string.
select(int): Selects the item at the specified index in the scrolling list.
setMultipleMode(boolean): Sets the flag that determines whether this list allows multiple selections.
setMultipleSelections(boolean): Deprecated.

List

 public List()

Creates a new scrolling list. Initially there are no visible lines, and only one item can be selected from the list.

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.

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.

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

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

getItemCount

 public int getItemCount()

Gets the number of items in the list.

Returns:: the number of items in the list.
See Also:: getItem

countItems

 public int countItems()

Note: countItems() is 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 synchronized String[] getItems()

Gets the items in the list.

Returns:: a string array containing items of the list.
See Also:: select, deselect, isIndexSelected

add

 public void add(String item)

Adds the specified item to the end of scrolling list.

Parameters:: item - the item to be added.

addItem

 public void addItem(String item)

Adds the specified item to the end of scrolling list.

Parameters:: item - the item to be added.

add

 public void add(String item,
                 int index)

Adds the specified item to the end of the scrolling list. The index is zero-based. If value of the index is -1 then the item is added to the end. If value of the index is greater than the number of items in the list, the item is added at the end.

Parameters:: item - the item to be added.; index - the position at which to add the item.

addItem

 public synchronized void addItem(String item,
                                  int index)

Parameters:: item - the item to be added.; index - the position at which to add the item.

replaceItem

 public synchronized 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.

See Also:: remove, delItems

clear

 public synchronized void clear()

Note: clear() is deprecated. As of JDK version 1.1, replaced by removeAll().

remove

 public synchronized 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.

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.
See Also:: add

delItem

 public void delItem(int position)

Removes the item at the specified position from this list.

getSelectedIndex

 public synchronized 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, deselect, isIndexSelected

getSelectedIndexes

 public synchronized int[] getSelectedIndexes()

Gets the selected indexes on the list.

Returns:: an array of the selected indexes of this scrolling list.
See Also:: select, deselect, isIndexSelected

getSelectedItem

 public synchronized 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, deselect, isIndexSelected

getSelectedItems

 public synchronized String[] getSelectedItems()

Get the selected items on this scrolling list.

Returns:: an array of the selected items on this scrolling list.
See Also:: select, deselect, isIndexSelected

getSelectedObjects

 public Object[] getSelectedObjects()

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

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, isIndexSelected

deselect

 public synchronized 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, getSelectedItem, isIndexSelected

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.
See Also:: select, deselect

isSelected

 public boolean isSelected(int index)

Note: isSelected() is 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.
See Also:: setMultipleMode

allowsMultipleSelections

 public boolean allowsMultipleSelections()

Note: allowsMultipleSelections() is 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.
See Also:: isMultipleMode

setMultipleSelections

 public synchronized void setMultipleSelections(boolean b)

Note: setMultipleSelections() is 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

makeVisible

 public synchronized 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.
See Also:: getPreferredSize

preferredSize

 public Dimension preferredSize(int rows)

Note: preferredSize() is deprecated. As of JDK version 1.1, replaced by getPreferredSize(int).

getPreferredSize

 public Dimension getPreferredSize()

Gets the preferred size of this scrolling list.

Returns:: the preferred dimensions for displaying this scrolling list.
Overrides:: getPreferredSize in class Component
See Also:: getPreferredSize

preferredSize

 public Dimension preferredSize()

Note: preferredSize() is 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.
See Also:: getMinimumSize

minimumSize

 public Dimension minimumSize(int rows)

Note: minimumSize() is deprecated. As of JDK version 1.1, replaced by getMinimumSize(int).

getMinimumSize

 public Dimension getMinimumSize()

Determines the minimum size of this scrolling list.

Returns:: the minimum dimensions needed to display this scrolling list.
Overrides:: getMinimumSize in class Component
See Also:: getMinimumSize

minimumSize

 public Dimension minimumSize()

Note: minimumSize() is deprecated. As of JDK version 1.1, replaced by getMinimumSize().

Overrides:: minimumSize in class Component

addItemListener

 public synchronized void addItemListener(ItemListener l)

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

Parameters:: l - the item listener.
See Also:: ItemEvent, ItemListener, removeItemListener

removeItemListener

 public synchronized void removeItemListener(ItemListener l)

Removes the specified item listener so that it no longer receives item events from this list.

Parameters:: l - the item listener.
See Also:: ItemEvent, ItemListener, addItemListener

addActionListener

 public synchronized 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.

Parameters:: l - the action listener.
See Also:: ActionEvent, ActionListener, removeActionListener

removeActionListener

 public synchronized 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.

Parameters:: l - the action listener.
See Also:: ActionEvent, ActionListener, addActionListener

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.

Parameters:: e - the event.
Overrides:: processEvent in class Component
See Also:: ActionEvent, ItemEvent, processActionEvent, processItemEvent

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.
See Also:: ItemEvent, ItemListener, addItemListener, enableEvents

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.
See Also:: ActionEvent, ActionListener, addActionListener, enableEvents

paramString

 protected String paramString()

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

Returns:: the parameter string of this scrolling list.
Overrides:: paramString in class Component

delItems

 public synchronized void delItems(int start,
                                   int end)

Note: delItems() is 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.

All Packages  Class Hierarchy  This Package  Previous  Next  Index

Submit a bug or feature - Version 1.1.8 of Java Platform API Specification
Java is a trademark or registered trademark of Sun Microsystems, Inc. in the US and other countries.
Copyright 1995-1999 Sun Microsystems, Inc. 901 San Antonio Road,
Palo Alto, California, 94303, U.S.A. All Rights Reserved.