public class List extends Componentimplements ItemSelectable , Accessible
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:
If the List allows multiple selections, then 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. If the List does not allow multiple selections, selecting an item causes any other selected item to be deselected.
Note that the list in the example shown was created with four visible rows. Once the list has been created, the number of visible rows cannot be changed. A default List is created with four rows, so that lst = new List() is equivalent to list = new List(4, false).
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 by the user, 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 by the user, 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 Form
| Modifier and Type | Class and Description |
|---|---|
protected class |
List
This class implements accessibility support for the
List class.
|
Component.AccessibleAWTComponent , Component.BaselineResizeBehavior , Component.BltBufferStrategy , Component.FlipBufferStrategy accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENTABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH| Constructor and Description |
|---|
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.
|
| Modifier and Type | Method and Description |
|---|---|
void |
add(String
Adds the specified item to the end of scrolling list.
|
void |
add(String
Adds the specified item to the the scrolling list at the position indicated by the index.
|
void |
addActionListener(ActionListener
Adds the specified action listener to receive action events from this list.
|
void |
addItem(String
Deprecated.
replaced by
add(String).
|
void |
addItem(String
Deprecated.
replaced by
add(String, int).
|
void |
addItemListener(ItemListener
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.
|
ActionListener |
getActionListeners()
Returns an array of all the action listeners registered on this list.
|
String |
getItem(int index)
Gets the item associated with the specified index.
|
int |
getItemCount()
Gets the number of items in the list.
|
ItemListener |
getItemListeners()
Returns an array of all the item listeners registered on this list.
|
String |
getItems()
Gets the items in the list.
|
<T extends EventListener |
getListeners(Class
Returns an array of all the objects currently registered as
FooListeners upon this
List.
|
Dimension |
getMinimumSize()
Determines the minimum size of this scrolling list.
|
Dimension |
getMinimumSize(int rows)
Gets the minimum 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()
Gets 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()
Gets the selected item on this scrolling list.
|
String |
getSelectedItems()
Gets the selected items on this scrolling list.
|
Object |
getSelectedObjects()
Gets the selected items on this scrolling 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
Processes action events occurring on this component by dispatching them to any registered
ActionListener objects.
|
protected void |
processEvent(AWTEvent
Processes events on this scrolling list.
|
protected void |
processItemEvent(ItemEvent
Processes item events occurring on this list by dispatching them to any registered
ItemListener objects.
|
void |
remove(int position)
Removes the item at the specified position from this scrolling list.
|
void |
remove(String
Removes the first occurrence of an item from the list.
|
void |
removeActionListener(ActionListener
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
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
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).
|
action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBaseline, getBaselineResizeBehavior, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeys, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusCycleRoot, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, 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, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, revalidate, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, update, validatepublic List()
throws HeadlessException
List(0, false). Also note that the number of visible lines in the list cannot be changed after it has been created.
HeadlessException - if GraphicsEnvironment.isHeadless() returns true.
GraphicsEnvironment.isHeadless()
public List(int rows)
throws HeadlessException
List(rows, false). Also note that the number of visible rows in the list cannot be changed after it has been created.
rows - the number of items to show.
HeadlessException - if GraphicsEnvironment.isHeadless() returns true.
GraphicsEnvironment.isHeadless()
public List(int rows,
boolean multipleMode)
throws HeadlessException
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.
HeadlessException - if GraphicsEnvironment.isHeadless() returns true.
GraphicsEnvironment.isHeadless()
public void addNotify()
addNotify in class
Component
Component.isDisplayable() ,
Component.removeNotify() ,
Component.invalidate()
public void removeNotify()
removeNotify in class
Component
Component.isDisplayable() ,
Component.addNotify()
public int getItemCount()
getItem(int)
@Deprecated public int countItems()
getItemCount().
public StringgetItem(int index)
index - the position of the item
getItemCount()
public String[] getItems()
select(int),
deselect(int),
isIndexSelected(int)
public void add(Stringitem)
item - the item to be added
@Deprecated public void addItem(Stringitem)
add(String).
public void add(Stringitem, 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
@Deprecated public void addItem(Stringitem, int index)
add(String, int).
public void replaceItem(StringnewValue, int index)
newValue - a new string to replace an existing item
index - the position of the item to replace
ArrayIndexOutOfBoundsException - if
index is out of range
public void removeAll()
remove(java.lang.String),
delItems(int, int)
@Deprecated public void clear()
removeAll().
public void remove(Stringitem)
item - the item to remove from the list
IllegalArgumentException - if the item doesn't exist in the list
public void remove(int position)
position - the index of the item to delete
ArrayIndexOutOfBoundsException - if the
position is less than 0 or greater than
getItemCount()-1
add(String, int)
@Deprecated public void delItem(int position)
remove(String) and remove(int).
public int getSelectedIndex()
-1 is returned.
select(int),
deselect(int),
isIndexSelected(int)
public int[] getSelectedIndexes()
select(int),
deselect(int),
isIndexSelected(int)
public StringgetSelectedItem()
null is returned.
select(int),
deselect(int),
isIndexSelected(int)
public String[] getSelectedItems()
select(int),
deselect(int),
isIndexSelected(int)
public Object[] getSelectedObjects()
getSelectedObjects in interface
ItemSelectable
Objects representing the selected items on this scrolling list; if no item is selected, a zero-length array is returned.
getSelectedItems(),
ItemSelectable
public void select(int index)
Note that passing out of range parameters is invalid, and will result in unspecified behavior.
Note that this method should be primarily used to initially select an item in this component. Programmatically calling this method will not trigger an ItemEvent. The only way to trigger an ItemEvent is by user interaction.
index - the position of the item to select
getSelectedItem(),
deselect(int),
isIndexSelected(int)
public void deselect(int index)
Note that passing out of range parameters is invalid, and will result in unspecified behavior.
If the item at the specified index is not selected, 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)
@Deprecated public boolean isSelected(int index)
isIndexSelected(int).
public int getRows()
List has been created, this number will never change.
public boolean isMultipleMode()
true if this list allows multiple selections; otherwise,
false
setMultipleMode(boolean)
@Deprecated 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()
@Deprecated 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 DimensiongetPreferredSize(int rows)
rows - number of rows in the list
Component.getPreferredSize()
@Deprecated public DimensionpreferredSize(int rows)
getPreferredSize(int).
public DimensiongetPreferredSize()
getPreferredSize in class
Component
Component.getPreferredSize()
@Deprecated public DimensionpreferredSize()
getPreferredSize().
public DimensiongetMinimumSize(int rows)
rows - number of rows in the list
Component.getMinimumSize()
@Deprecated public DimensionminimumSize(int rows)
getMinimumSize(int).
public DimensiongetMinimumSize()
getMinimumSize in class
Component
Component.getMinimumSize()
@Deprecated public DimensionminimumSize()
getMinimumSize().
public void addItemListener(ItemListenerl)
select or
deselect. If listener
l is
null, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
addItemListener in interface
ItemSelectable
l - the item listener
removeItemListener(java.awt.event.ItemListener),
getItemListeners(),
select(int),
deselect(int),
ItemEvent,
ItemListener
public void removeItemListener(ItemListenerl)
l is
null, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
removeItemListener in interface
ItemSelectable
l - the item listener
addItemListener(java.awt.event.ItemListener),
getItemListeners(),
ItemEvent,
ItemListener
public ItemListener[] getItemListeners()
ItemListeners or an empty array if no item listeners are currently registered
addItemListener(java.awt.event.ItemListener),
removeItemListener(java.awt.event.ItemListener),
ItemEvent,
ItemListener
public void addActionListener(ActionListenerl)
If listener l is null, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the action listener
removeActionListener(java.awt.event.ActionListener),
getActionListeners(),
ActionEvent,
ActionListener
public void removeActionListener(ActionListenerl)
l is
null, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the action listener
addActionListener(java.awt.event.ActionListener),
getActionListeners(),
ActionEvent,
ActionListener
public ActionListener[] getActionListeners()
ActionListeners or an empty array if no action listeners are currently registered
addActionListener(java.awt.event.ActionListener),
removeActionListener(java.awt.event.ActionListener),
ActionEvent,
ActionListener
public <T extends EventListener> T[] getListeners(Class <T> listenerType)
FooListeners upon this
List.
FooListeners are registered using the
addFooListener method.
You can specify the listenerType argument with a class literal, such as FooListener.class. For example, you can query a List l for its item listeners with the following code:
ItemListener[] ils = (ItemListener[])(l.getListeners(ItemListener.class));If no such listeners exist, this method returns an empty array.
getListeners in class
Component
listenerType - the type of listeners requested; this parameter should specify an interface that descends from
java.util.EventListener
FooListeners on this list, or an empty array if no such listeners have been added
ClassCastException - if
listenerType doesn't specify a class or interface that implements
java.util.EventListener
getItemListeners()
protected void processEvent(AWTEvente)
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.
Note that if the event parameter is null the behavior is unspecified and may result in an exception.
processEvent in class
Component
e - the event
ActionEvent,
ItemEvent,
processActionEvent(java.awt.event.ActionEvent),
processItemEvent(java.awt.event.ItemEvent)
protected void processItemEvent(ItemEvente)
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. Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the item event
ItemEvent,
ItemListener,
addItemListener(java.awt.event.ItemListener),
Component.enableEvents(long)
protected void processActionEvent(ActionEvente)
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. Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the action event
ActionEvent,
ActionListener,
addActionListener(java.awt.event.ActionListener),
Component.enableEvents(long)
protected StringparamString()
paramString in class
Component
@Deprecated public void delItems(int start, int end)
public AccessibleContextgetAccessibleContext()
AccessibleContext associated with this
List. For lists, the
AccessibleContext takes the form of an
AccessibleAWTList. A new
AccessibleAWTList instance is created, if necessary.
getAccessibleContext in interface
Accessible
getAccessibleContext in class
Component
AccessibleAWTList that serves as the
AccessibleContext of this
List