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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.

Since:
JDK1.0
See Also:
ItemEvent, ItemListener, ActionEvent, ActionListener

Fields inherited from class java.awt.Component
 BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
 

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 end of the scrolling list.
void  addActionListener(ActionListener l)
Adds the specified action listener to receive action events from this list.
void  addItem(String item)
  Deprecated
void  addItem(String item, int index)
  Deprecated
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
void  clear()
  Deprecated
int  countItems()
  Deprecated
void  delItem(int position)
  Deprecated
void  delItems(int start, int end)
  Deprecated
void  deselect(int index)
Deselects the item at the specified index.
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.
Dimension  getMinimumSize(int rows)
Gets the minumum dimensions for a list with the specified number of rows.
Dimension  getMinimumSize()
Determines the minimum size of this scrolling list.
Dimension  getPreferredSize(int rows)
Gets the preferred dimensions for a list with the specified number of rows.
Dimension  getPreferredSize()
Gets the preferred size of this scrolling list.
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
void  makeVisible(int index)
Makes the item at the specified index visible.
Dimension  minimumSize(int rows)
  Deprecated
Dimension  minimumSize()
  Deprecated
String  paramString()
Returns the parameter string representing the state of this scrolling list.
Dimension  preferredSize(int rows)
  Deprecated
Dimension  preferredSize()
  Deprecated
void  processActionEvent(ActionEvent e)
Processes action events occurring on this component by dispatching them to any registered ActionListener objects.
void  processEvent(AWTEvent e)
Processes events on this scrolling list.
void  processItemEvent(ItemEvent e)
Processes item events occurring on this list by dispatching them to any registered ItemListener objects.
void  remove(String item)
Removes the first occurrence of an item from the list.
void  remove(int position)
Remove the item at the specified position from this scrolling 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
 
Methods inherited from class java.awt.Component
 action, add, addComponentListener, addFocusListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addNotify, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBounds, getColorModel, getComponentAt, getComponentAt, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getHeight, getInputContext, getInputMethodRequests, getLocale, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getName, getParent, getPeer, getPreferredSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isDisplayable, 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, paramString, postEvent, preferredSize, prepareImage, prepareImage, print, printAll, processComponentEvent, processEvent, processFocusEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, remove, removeComponentListener, removeFocusListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBackground, setBounds, setBounds, 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, toString, wait, wait, wait
 

Constructor Detail

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.
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

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 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)
Note: addItem() is deprecated.replaced by add(String).


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 void addItem(String item,
                    int index)
Note: addItem() is 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.
See Also:
remove, delItems

clear

public void clear()
Note: clear() is 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.

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(String, int)

delItem

public void delItem(int position)
Note: delItem() is 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, deselect, isIndexSelected

getSelectedIndexes

public 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 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 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.
Implements:
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, isIndexSelected

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, 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 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 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 void addItemListener(ItemListener l)
Adds the specified item listener to receive item events from this list.
Implements:
addItemListener in interface ItemSelectable
Parameters:
l - the item listener.
See Also:
ItemEvent, ItemListener, removeItemListener

removeItemListener

public void removeItemListener(ItemListener l)
Removes the specified item listener so that it no longer receives item events from this list.
Implements:
removeItemListener in interface ItemSelectable
Parameters:
l - the item listener.
See Also:
ItemEvent, ItemListener, addItemListener

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

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.
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:

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:

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 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.


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