java.lang.Object
java.awt.Component
java.awt.List
public class 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:
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
protected class List.AccessibleAWTList
List class. Constructor Summary List()
List(int rows)
List(int rows, boolean multipleMode)
void add(String item)
void add(String item, int index)
void addActionListener(ActionListener l)
void addItem(String item)
add(String). void addItem(String item, int index)
add(String, int). void addItemListener(ItemListener l)
void addNotify()
boolean allowsMultipleSelections()
isMultipleMode(). void clear()
removeAll(). int countItems()
getItemCount(). void delItem(int position)
remove(String) and remove(int). void delItems(int start, int end)
void deselect(int index)
AccessibleContext getAccessibleContext()
AccessibleContext associated with this List. ActionListener[] getActionListeners()
String getItem(int index)
int getItemCount()
ItemListener[] getItemListeners()
String[] getItems()
<T extends EventListener>
T[] getListeners(Class<T> listenerType)
FooListeners upon this List. Dimension getMinimumSize()
Dimension getMinimumSize(int rows)
Dimension getPreferredSize()
Dimension getPreferredSize(int rows)
int getRows()
int getSelectedIndex()
int[] getSelectedIndexes()
String getSelectedItem()
String[] getSelectedItems()
Object[] getSelectedObjects()
int getVisibleIndex()
makeVisible. boolean isIndexSelected(int index)
boolean isMultipleMode()
boolean isSelected(int index)
isIndexSelected(int). void makeVisible(int index)
Dimension minimumSize()
getMinimumSize(). Dimension minimumSize(int rows)
getMinimumSize(int). protected String paramString()
Dimension preferredSize()
getPreferredSize(). Dimension preferredSize(int rows)
getPreferredSize(int). protected void processActionEvent(ActionEvent e)
ActionListener objects. protected void processEvent(AWTEvent e)
protected void processItemEvent(ItemEvent e)
ItemListener objects. void remove(int position)
void remove(String item)
void removeActionListener(ActionListener l)
void removeAll()
void removeItemListener(ItemListener l)
void removeNotify()
void replaceItem(String newValue, int index)
void select(int index)
void setMultipleMode(boolean b)
void setMultipleSelections(boolean b)
setMultipleMode(boolean). Methods inherited from class java.awt.Component 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, 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, 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, validate List
public 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()
public void removeNotify()
removeNotify in class Component
Component.isDisplayable(), Component.addNotify()
public int getItemCount()
getItem(int)
@Deprecated 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
@Deprecated 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
@Deprecated
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
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(String item)
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 String getSelectedItem()
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 Dimension getPreferredSize(int rows)
rows - number of rows in the list
Component.getPreferredSize()
@Deprecated public Dimension preferredSize(int rows)
getPreferredSize(int).
public Dimension getPreferredSize()
getPreferredSize in class Component
Component.getPreferredSize()
@Deprecated public Dimension preferredSize()
getPreferredSize().
preferredSize in class Component
public Dimension getMinimumSize(int rows)
rows - number of rows in the list
Component.getMinimumSize()
@Deprecated public Dimension minimumSize(int rows)
getMinimumSize(int).
public Dimension getMinimumSize()
getMinimumSize in class Component
Component.getMinimumSize()
@Deprecated public Dimension minimumSize()
getMinimumSize().
minimumSize in class Component
public void addItemListener(ItemListener l)
select or deselect. If listener l is null, no exception is thrown and no action is performed.
addItemListener in interface ItemSelectable
l - the item listener
removeItemListener(java.awt.event.ItemListener), getItemListeners(), select(int), deselect(int), ItemEvent, ItemListener
public void removeItemListener(ItemListener l)
l is null, no exception is thrown and no action is performed.
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(ActionListener l)
If listener l is null, no exception is thrown and no action is performed.
l - the action listener
removeActionListener(java.awt.event.ActionListener), getActionListeners(), ActionEvent, ActionListener
public void removeActionListener(ActionListener l)
l is null, no exception is thrown and no action is performed.
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(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.
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(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.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(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.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 String paramString()
paramString in class Component
@Deprecated
public void delItems(int start,
int end)
public AccessibleContext getAccessibleContext()
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
Copyright © 2004, 2010 Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
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