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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.

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)
addItem(String, int)
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)

add

     public synchronized 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)

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 synchronized 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 synchronized 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 synchronized 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 synchronized 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.

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