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JavaTM 2 Platform Standard Edition |
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SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Object | +--java.awt.Component | +--java.awt.List
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.
ItemEvent
,
ItemListener
,
ActionEvent
,
ActionListener
, Serialized FormFields 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 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. |
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()
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.lang.Object |
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
wait,
wait,
wait |
Constructor Detail |
public List()
public List(int rows)
rows
- the number of items to show.public List(int rows, boolean multipleMode)
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.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 |
public void addNotify()
public void removeNotify()
Component.isDisplayable()
,
Component.addNotify()
public int getItemCount()
getItem(int)
public int countItems()
getItemCount()
.
public String getItem(int index)
index
- the position of the item.getItemCount()
public String[] getItems()
select(int)
,
deselect(int)
,
isIndexSelected(int)
public void add(String item)
item
- the item to be added.public void addItem(String item)
add(String)
.
public void add(String item, int index)
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.public void addItem(String item, int index)
add(String, int)
.
public void replaceItem(String newValue, int index)
newValue
- a new string to replace an existing item.index
- the position of the item to replace.public void removeAll()
remove(java.lang.String)
,
delItems(int, int)
public void clear()
removeAll()
.
public void remove(String item)
item
- the item to remove from the list.public void remove(int position)
position
- the index of the item to delete.position
is less than 0 or
greater than getItemCount()-1
add(String, int)
public void delItem(int position)
remove(String)
and remove(int)
.
public int getSelectedIndex()
-1
if no item is selected,
or if more that one item is selected.select(int)
,
deselect(int)
,
isIndexSelected(int)
public int[] getSelectedIndexes()
select(int)
,
deselect(int)
,
isIndexSelected(int)
public String getSelectedItem()
select(int)
,
deselect(int)
,
isIndexSelected(int)
public String[] getSelectedItems()
select(int)
,
deselect(int)
,
isIndexSelected(int)
public Object[] getSelectedObjects()
ItemSelectable
public void select(int index)
index
- the position of the item to select.getSelectedItem()
,
deselect(int)
,
isIndexSelected(int)
public void deselect(int index)
If the item at the specified index is not selected, or if the index is out of range, then the operation is ignored.
index
- the position of the item to deselect.select(int)
,
getSelectedItem()
,
isIndexSelected(int)
public boolean isIndexSelected(int index)
index
- the item to be checked.true
if the specified item has been
selected; false
otherwise.select(int)
,
deselect(int)
public boolean isSelected(int index)
isIndexSelected(int)
.
public int getRows()
public boolean isMultipleMode()
true
if this list allows multiple
selections; otherwise, false
.setMultipleMode(boolean)
public boolean allowsMultipleSelections()
isMultipleMode()
.
public void setMultipleMode(boolean b)
b
- if true
then multiple selections
are allowed; otherwise, only one item from
the list can be selected at once.isMultipleMode()
public void setMultipleSelections(boolean b)
setMultipleMode(boolean)
.
public int getVisibleIndex()
makeVisible
.makeVisible(int)
public void makeVisible(int index)
index
- the position of the item.getVisibleIndex()
public Dimension getPreferredSize(int rows)
rows
- number of rows in the list.Component.getPreferredSize()
public Dimension preferredSize(int rows)
getPreferredSize(int)
.
public Dimension getPreferredSize()
Component.getPreferredSize()
public Dimension preferredSize()
getPreferredSize()
.
public Dimension getMinimumSize(int rows)
rows
- number of rows in the list.Component.getMinimumSize()
public Dimension minimumSize(int rows)
getMinimumSize(int)
.
public Dimension getMinimumSize()
Component.getMinimumSize()
public Dimension minimumSize()
getMinimumSize()
.
public void addItemListener(ItemListener l)
l
- the item listener.ItemEvent
,
ItemListener
,
removeItemListener(java.awt.event.ItemListener)
public void removeItemListener(ItemListener l)
l
- the item listener.ItemEvent
,
ItemListener
,
addItemListener(java.awt.event.ItemListener)
public void addActionListener(ActionListener l)
l
- the action listener.ActionEvent
,
ActionListener
,
removeActionListener(java.awt.event.ActionListener)
public void removeActionListener(ActionListener l)
l
- the action listener.ActionEvent
,
ActionListener
,
addActionListener(java.awt.event.ActionListener)
protected void processEvent(AWTEvent e)
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.e
- the event.ActionEvent
,
ItemEvent
,
processActionEvent(java.awt.event.ActionEvent)
,
processItemEvent(java.awt.event.ItemEvent)
protected void processItemEvent(ItemEvent e)
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:
ItemListener
object is registered
via addItemListener
.
enableEvents
.
e
- the item event.ItemEvent
,
ItemListener
,
addItemListener(java.awt.event.ItemListener)
,
Component.enableEvents(long)
protected void processActionEvent(ActionEvent e)
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:
ActionListener
object is registered
via addActionListener
.
enableEvents
.
e
- the action event.ActionEvent
,
ActionListener
,
addActionListener(java.awt.event.ActionListener)
,
Component.enableEvents(long)
protected String paramString()
public void delItems(int start, int end)
|
JavaTM 2 Platform Standard Edition |
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PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |