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The List.java Java example source code
/*
* Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.awt;
import java.util.Vector;
import java.util.Locale;
import java.util.EventListener;
import java.awt.peer.ListPeer;
import java.awt.event.*;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import javax.accessibility.*;
/**
* The <code>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.
* <p>
* For example, the code . . .
*
* <hr> * 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);
* </pre>
* <p>
* where <code>cnt is a container, produces the following
* scrolling list:
* <p>
* <img src="doc-files/List-1.gif"
* alt="Shows a list containing: Venus, Earth, JavaSoft, and Mars. Javasoft is selected." style="float:center; margin: 7px 10px;">
* <p>
* 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 <code>false. If the List does not allow multiple
* selections, selecting an item causes any other selected item
* to be deselected.
* <p>
* 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 <code>List is created with
* four rows, so that <code>lst = new List() is equivalent to
* <code>list = new List(4, false).
* <p>
* Beginning with Java 1.1, the Abstract Window Toolkit
* sends the <code>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.)
* <p>
* When an item is selected or deselected by the user, AWT sends an instance
* of <code>ItemEvent to the list.
* When the user double-clicks on an item in a scrolling list,
* AWT sends an instance of <code>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.
* <p>
* 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
* <code>ItemListener or ActionListener
* as appropriate and register the new listener to receive
* events from this list.
* <p>
* 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.
* @author Sami Shaio
* @see java.awt.event.ItemEvent
* @see java.awt.event.ItemListener
* @see java.awt.event.ActionEvent
* @see java.awt.event.ActionListener
* @since JDK1.0
*/
public class List extends Component implements ItemSelectable, Accessible {
/**
* A vector created to contain items which will become
* part of the List Component.
*
* @serial
* @see #addItem(String)
* @see #getItem(int)
*/
Vector<String> items = new Vector<>();
/**
* This field will represent the number of visible rows in the
* <code>List Component. It is specified only once, and
* that is when the list component is actually
* created. It will never change.
*
* @serial
* @see #getRows()
*/
int rows = 0;
/**
* <code>multipleMode is a variable that will
* be set to <code>true if a list component is to be set to
* multiple selection mode, that is where the user can
* select more than one item in a list at one time.
* <code>multipleMode will be set to false if the
* list component is set to single selection, that is where
* the user can only select one item on the list at any
* one time.
*
* @serial
* @see #isMultipleMode()
* @see #setMultipleMode(boolean)
*/
boolean multipleMode = false;
/**
* <code>selected is an array that will contain
* the indices of items that have been selected.
*
* @serial
* @see #getSelectedIndexes()
* @see #getSelectedIndex()
*/
int selected[] = new int[0];
/**
* This variable contains the value that will be used
* when trying to make a particular list item visible.
*
* @serial
* @see #makeVisible(int)
*/
int visibleIndex = -1;
transient ActionListener actionListener;
transient ItemListener itemListener;
private static final String base = "list";
private static int nameCounter = 0;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = -3304312411574666869L;
/**
* Creates a new scrolling list.
* By default, there are four visible lines and multiple selections are
* not allowed. Note that this is a convenience method for
* <code>List(0, false). Also note that the number of visible
* lines in the list cannot be changed after it has been created.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public List() throws HeadlessException {
this(0, false);
}
/**
* Creates a new scrolling list initialized with the specified
* number of visible lines. By default, multiple selections are
* not allowed. Note that this is a convenience method for
* <code>List(rows, false). Also note that the number
* of visible rows in the list cannot be changed after it has
* been created.
* @param rows the number of items to show.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
* @since JDK1.1
*/
public List(int rows) throws HeadlessException {
this(rows, false);
}
/**
* The default number of visible rows is 4. A list with
* zero rows is unusable and unsightly.
*/
final static int DEFAULT_VISIBLE_ROWS = 4;
/**
* Creates a new scrolling list initialized to display the specified
* number of rows. Note that if zero rows are specified, then
* the list will be created with a default of four rows.
* Also note that the number of visible rows in the list cannot
* be changed after it has been created.
* If the value of <code>multipleMode is
* <code>true, then the user can select multiple items from
* the list. If it is <code>false, only one item at a time
* can be selected.
* @param rows the number of items to show.
* @param multipleMode if <code>true,
* then multiple selections are allowed;
* otherwise, only one item can be selected at a time.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public List(int rows, boolean multipleMode) throws HeadlessException {
GraphicsEnvironment.checkHeadless();
this.rows = (rows != 0) ? rows : DEFAULT_VISIBLE_ROWS;
this.multipleMode = multipleMode;
}
/**
* Construct a name for this component. Called by
* <code>getName when the name is null.
*/
String constructComponentName() {
synchronized (List.class) {
return base + nameCounter++;
}
}
/**
* Creates the peer for the list. The peer allows us to modify the
* list's appearance without changing its functionality.
*/
public void addNotify() {
synchronized (getTreeLock()) {
if (peer == null)
peer = getToolkit().createList(this);
super.addNotify();
}
}
/**
* Removes the peer for this list. The peer allows us to modify the
* list's appearance without changing its functionality.
*/
public void removeNotify() {
synchronized (getTreeLock()) {
ListPeer peer = (ListPeer)this.peer;
if (peer != null) {
selected = peer.getSelectedIndexes();
}
super.removeNotify();
}
}
/**
* Gets the number of items in the list.
* @return the number of items in the list
* @see #getItem
* @since JDK1.1
*/
public int getItemCount() {
return countItems();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>getItemCount().
*/
@Deprecated
public int countItems() {
return items.size();
}
/**
* Gets the item associated with the specified index.
* @return an item that is associated with
* the specified index
* @param index the position of the item
* @see #getItemCount
*/
public String getItem(int index) {
return getItemImpl(index);
}
// NOTE: This method may be called by privileged threads.
// We implement this functionality in a package-private method
// to insure that it cannot be overridden by client subclasses.
// DO NOT INVOKE CLIENT CODE ON THIS THREAD!
final String getItemImpl(int index) {
return items.elementAt(index);
}
/**
* Gets the items in the list.
* @return a string array containing items of the list
* @see #select
* @see #deselect
* @see #isIndexSelected
* @since JDK1.1
*/
public synchronized String[] getItems() {
String itemCopies[] = new String[items.size()];
items.copyInto(itemCopies);
return itemCopies;
}
/**
* Adds the specified item to the end of scrolling list.
* @param item the item to be added
* @since JDK1.1
*/
public void add(String item) {
addItem(item);
}
/**
* @deprecated replaced by <code>add(String).
*/
@Deprecated
public void addItem(String item) {
addItem(item, -1);
}
/**
* Adds the specified item to the the scrolling list
* at the position indicated by the index. The index is
* zero-based. If the value of the index is less than zero,
* or if the value of the index is greater than or equal to
* the number of items in the list, then the item is added
* to the end of the list.
* @param item the item to be added;
* if this parameter is <code>null then the item is
* treated as an empty string, <code>""
* @param index the position at which to add the item
* @since JDK1.1
*/
public void add(String item, int index) {
addItem(item, index);
}
/**
* @deprecated replaced by <code>add(String, int).
*/
@Deprecated
public synchronized void addItem(String item, int index) {
if (index < -1 || index >= items.size()) {
index = -1;
}
if (item == null) {
item = "";
}
if (index == -1) {
items.addElement(item);
} else {
items.insertElementAt(item, index);
}
ListPeer peer = (ListPeer)this.peer;
if (peer != null) {
peer.add(item, index);
}
}
/**
* Replaces the item at the specified index in the scrolling list
* with the new string.
* @param newValue a new string to replace an existing item
* @param index the position of the item to replace
* @exception ArrayIndexOutOfBoundsException if <code>index
* is out of range
*/
public synchronized void replaceItem(String newValue, int index) {
remove(index);
add(newValue, index);
}
/**
* Removes all items from this list.
* @see #remove
* @see #delItems
* @since JDK1.1
*/
public void removeAll() {
clear();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>removeAll().
*/
@Deprecated
public synchronized void clear() {
ListPeer peer = (ListPeer)this.peer;
if (peer != null) {
peer.removeAll();
}
items = new Vector<>();
selected = new int[0];
}
/**
* Removes the first occurrence of an item from the list.
* If the specified item is selected, and is the only selected
* item in the list, the list is set to have no selection.
* @param item the item to remove from the list
* @exception IllegalArgumentException
* if the item doesn't exist in the list
* @since JDK1.1
*/
public synchronized void remove(String item) {
int index = items.indexOf(item);
if (index < 0) {
throw new IllegalArgumentException("item " + item +
" not found in list");
} else {
remove(index);
}
}
/**
* Removes the item at the specified position
* from this scrolling list.
* If the item with the specified position is selected, and is the
* only selected item in the list, the list is set to have no selection.
* @param position the index of the item to delete
* @see #add(String, int)
* @since JDK1.1
* @exception ArrayIndexOutOfBoundsException
* if the <code>position is less than 0 or
* greater than <code>getItemCount()-1
*/
public void remove(int position) {
delItem(position);
}
/**
* @deprecated replaced by <code>remove(String)
* and <code>remove(int).
*/
@Deprecated
public void delItem(int position) {
delItems(position, position);
}
/**
* Gets the index of the selected item on the list,
*
* @return the index of the selected item;
* if no item is selected, or if multiple items are
* selected, <code>-1 is returned.
* @see #select
* @see #deselect
* @see #isIndexSelected
*/
public synchronized int getSelectedIndex() {
int sel[] = getSelectedIndexes();
return (sel.length == 1) ? sel[0] : -1;
}
/**
* Gets the selected indexes on the list.
*
* @return an array of the selected indexes on this scrolling list;
* if no item is selected, a zero-length array is returned.
* @see #select
* @see #deselect
* @see #isIndexSelected
*/
public synchronized int[] getSelectedIndexes() {
ListPeer peer = (ListPeer)this.peer;
if (peer != null) {
selected = peer.getSelectedIndexes();
}
return selected.clone();
}
/**
* Gets the selected item on this scrolling list.
*
* @return the selected item on the list;
* if no item is selected, or if multiple items are
* selected, <code>null is returned.
* @see #select
* @see #deselect
* @see #isIndexSelected
*/
public synchronized String getSelectedItem() {
int index = getSelectedIndex();
return (index < 0) ? null : getItem(index);
}
/**
* Gets the selected items on this scrolling list.
*
* @return an array of the selected items on this scrolling list;
* if no item is selected, a zero-length array is returned.
* @see #select
* @see #deselect
* @see #isIndexSelected
*/
public synchronized String[] getSelectedItems() {
int sel[] = getSelectedIndexes();
String str[] = new String[sel.length];
for (int i = 0 ; i < sel.length ; i++) {
str[i] = getItem(sel[i]);
}
return str;
}
/**
* Gets the selected items on this scrolling list in an array of Objects.
* @return an array of <code>Objects representing the
* selected items on this scrolling list;
* if no item is selected, a zero-length array is returned.
* @see #getSelectedItems
* @see ItemSelectable
*/
public Object[] getSelectedObjects() {
return getSelectedItems();
}
/**
* Selects the item at the specified index in the scrolling list.
*<p>
* Note that passing out of range parameters is invalid,
* and will result in unspecified behavior.
*
* <p>Note that this method should be primarily used to
* initially select an item in this component.
* Programmatically calling this method will <i>not trigger
* an <code>ItemEvent. The only way to trigger an
* <code>ItemEvent is by user interaction.
*
* @param index the position of the item to select
* @see #getSelectedItem
* @see #deselect
* @see #isIndexSelected
*/
public void select(int index) {
// Bug #4059614: select can't be synchronized while calling the peer,
// because it is called from the Window Thread. It is sufficient to
// synchronize the code that manipulates 'selected' except for the
// case where the peer changes. To handle this case, we simply
// repeat the selection process.
ListPeer peer;
do {
peer = (ListPeer)this.peer;
if (peer != null) {
peer.select(index);
return;
}
synchronized(this)
{
boolean alreadySelected = false;
for (int i = 0 ; i < selected.length ; i++) {
if (selected[i] == index) {
alreadySelected = true;
break;
}
}
if (!alreadySelected) {
if (!multipleMode) {
selected = new int[1];
selected[0] = index;
} else {
int newsel[] = new int[selected.length + 1];
System.arraycopy(selected, 0, newsel, 0,
selected.length);
newsel[selected.length] = index;
selected = newsel;
}
}
}
} while (peer != this.peer);
}
/**
* Deselects the item at the specified index.
* <p>
* Note that passing out of range parameters is invalid,
* and will result in unspecified behavior.
* <p>
* If the item at the specified index is not selected,
* then the operation is ignored.
* @param index the position of the item to deselect
* @see #select
* @see #getSelectedItem
* @see #isIndexSelected
*/
public synchronized void deselect(int index) {
ListPeer peer = (ListPeer)this.peer;
if (peer != null) {
if (isMultipleMode() || (getSelectedIndex() == index)) {
peer.deselect(index);
}
}
for (int i = 0 ; i < selected.length ; i++) {
if (selected[i] == index) {
int newsel[] = new int[selected.length - 1];
System.arraycopy(selected, 0, newsel, 0, i);
System.arraycopy(selected, i+1, newsel, i, selected.length - (i+1));
selected = newsel;
return;
}
}
}
/**
* Determines if the specified item in this scrolling list is
* selected.
* @param index the item to be checked
* @return <code>true if the specified item has been
* selected; <code>false otherwise
* @see #select
* @see #deselect
* @since JDK1.1
*/
public boolean isIndexSelected(int index) {
return isSelected(index);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>isIndexSelected(int).
*/
@Deprecated
public boolean isSelected(int index) {
int sel[] = getSelectedIndexes();
for (int i = 0 ; i < sel.length ; i++) {
if (sel[i] == index) {
return true;
}
}
return false;
}
/**
* Gets the number of visible lines in this list. Note that
* once the <code>List has been created, this number
* will never change.
* @return the number of visible lines in this scrolling list
*/
public int getRows() {
return rows;
}
/**
* Determines whether this list allows multiple selections.
* @return <code>true if this list allows multiple
* selections; otherwise, <code>false
* @see #setMultipleMode
* @since JDK1.1
*/
public boolean isMultipleMode() {
return allowsMultipleSelections();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>isMultipleMode().
*/
@Deprecated
public boolean allowsMultipleSelections() {
return multipleMode;
}
/**
* Sets the flag that determines whether this list
* allows multiple selections.
* When the selection mode is changed from multiple-selection to
* single-selection, the selected items change as follows:
* If a selected item has the location cursor, only that
* item will remain selected. If no selected item has the
* location cursor, all items will be deselected.
* @param b if <code>true then multiple selections
* are allowed; otherwise, only one item from
* the list can be selected at once
* @see #isMultipleMode
* @since JDK1.1
*/
public void setMultipleMode(boolean b) {
setMultipleSelections(b);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>setMultipleMode(boolean).
*/
@Deprecated
public synchronized void setMultipleSelections(boolean b) {
if (b != multipleMode) {
multipleMode = b;
ListPeer peer = (ListPeer)this.peer;
if (peer != null) {
peer.setMultipleMode(b);
}
}
}
/**
* Gets the index of the item that was last made visible by
* the method <code>makeVisible.
* @return the index of the item that was last made visible
* @see #makeVisible
*/
public int getVisibleIndex() {
return visibleIndex;
}
/**
* Makes the item at the specified index visible.
* @param index the position of the item
* @see #getVisibleIndex
*/
public synchronized void makeVisible(int index) {
visibleIndex = index;
ListPeer peer = (ListPeer)this.peer;
if (peer != null) {
peer.makeVisible(index);
}
}
/**
* Gets the preferred dimensions for a list with the specified
* number of rows.
* @param rows number of rows in the list
* @return the preferred dimensions for displaying this scrolling list
* given that the specified number of rows must be visible
* @see java.awt.Component#getPreferredSize
* @since JDK1.1
*/
public Dimension getPreferredSize(int rows) {
return preferredSize(rows);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>getPreferredSize(int).
*/
@Deprecated
public Dimension preferredSize(int rows) {
synchronized (getTreeLock()) {
ListPeer peer = (ListPeer)this.peer;
return (peer != null) ?
peer.getPreferredSize(rows) :
super.preferredSize();
}
}
/**
* Gets the preferred size of this scrolling list.
* @return the preferred dimensions for displaying this scrolling list
* @see java.awt.Component#getPreferredSize
* @since JDK1.1
*/
public Dimension getPreferredSize() {
return preferredSize();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>getPreferredSize().
*/
@Deprecated
public Dimension preferredSize() {
synchronized (getTreeLock()) {
return (rows > 0) ?
preferredSize(rows) :
super.preferredSize();
}
}
/**
* Gets the minimum dimensions for a list with the specified
* number of rows.
* @param rows number of rows in the list
* @return the minimum dimensions for displaying this scrolling list
* given that the specified number of rows must be visible
* @see java.awt.Component#getMinimumSize
* @since JDK1.1
*/
public Dimension getMinimumSize(int rows) {
return minimumSize(rows);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>getMinimumSize(int).
*/
@Deprecated
public Dimension minimumSize(int rows) {
synchronized (getTreeLock()) {
ListPeer peer = (ListPeer)this.peer;
return (peer != null) ?
peer.getMinimumSize(rows) :
super.minimumSize();
}
}
/**
* Determines the minimum size of this scrolling list.
* @return the minimum dimensions needed
* to display this scrolling list
* @see java.awt.Component#getMinimumSize()
* @since JDK1.1
*/
public Dimension getMinimumSize() {
return minimumSize();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>getMinimumSize().
*/
@Deprecated
public Dimension minimumSize() {
synchronized (getTreeLock()) {
return (rows > 0) ? minimumSize(rows) : super.minimumSize();
}
}
/**
* Adds the specified item listener to receive item events from
* this list. Item events are sent in response to user input, but not
* in response to calls to <code>select or deselect.
* If listener <code>l is null,
* no exception is thrown and no action is performed.
* <p>Refer to for details on AWT's threading model.
*
* @param l the item listener
* @see #removeItemListener
* @see #getItemListeners
* @see #select
* @see #deselect
* @see java.awt.event.ItemEvent
* @see java.awt.event.ItemListener
* @since JDK1.1
*/
public synchronized void addItemListener(ItemListener l) {
if (l == null) {
return;
}
itemListener = AWTEventMulticaster.add(itemListener, l);
newEventsOnly = true;
}
/**
* Removes the specified item listener so that it no longer
* receives item events from this list.
* If listener <code>l is null,
* no exception is thrown and no action is performed.
* <p>Refer to for details on AWT's threading model.
*
* @param l the item listener
* @see #addItemListener
* @see #getItemListeners
* @see java.awt.event.ItemEvent
* @see java.awt.event.ItemListener
* @since JDK1.1
*/
public synchronized void removeItemListener(ItemListener l) {
if (l == null) {
return;
}
itemListener = AWTEventMulticaster.remove(itemListener, l);
}
/**
* Returns an array of all the item listeners
* registered on this list.
*
* @return all of this list's <code>ItemListeners
* or an empty array if no item
* listeners are currently registered
*
* @see #addItemListener
* @see #removeItemListener
* @see java.awt.event.ItemEvent
* @see java.awt.event.ItemListener
* @since 1.4
*/
public synchronized ItemListener[] getItemListeners() {
return getListeners(ItemListener.class);
}
/**
* Adds the specified action listener to receive action events from
* this list. Action events occur when a user double-clicks
* on a list item or types Enter when the list has the keyboard
* focus.
* <p>
* If listener <code>l is null,
* no exception is thrown and no action is performed.
* <p>Refer to for details on AWT's threading model.
*
* @param l the action listener
* @see #removeActionListener
* @see #getActionListeners
* @see java.awt.event.ActionEvent
* @see java.awt.event.ActionListener
* @since JDK1.1
*/
public synchronized void addActionListener(ActionListener l) {
if (l == null) {
return;
}
actionListener = AWTEventMulticaster.add(actionListener, l);
newEventsOnly = true;
}
/**
* 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.
* If listener <code>l is null,
* no exception is thrown and no action is performed.
* <p>Refer to for details on AWT's threading model.
*
* @param l the action listener
* @see #addActionListener
* @see #getActionListeners
* @see java.awt.event.ActionEvent
* @see java.awt.event.ActionListener
* @since JDK1.1
*/
public synchronized void removeActionListener(ActionListener l) {
if (l == null) {
return;
}
actionListener = AWTEventMulticaster.remove(actionListener, l);
}
/**
* Returns an array of all the action listeners
* registered on this list.
*
* @return all of this list's <code>ActionListeners
* or an empty array if no action
* listeners are currently registered
*
* @see #addActionListener
* @see #removeActionListener
* @see java.awt.event.ActionEvent
* @see java.awt.event.ActionListener
* @since 1.4
*/
public synchronized ActionListener[] getActionListeners() {
return getListeners(ActionListener.class);
}
/**
* Returns an array of all the objects currently registered
* as <code>FooListeners
* upon this <code>List.
* <code>FooListeners are registered using the
* <code>addFooListener method.
*
* <p>
* You can specify the <code>listenerType argument
* with a class literal, such as
* <code>FooListener.class.
* For example, you can query a
* <code>List l
* for its item listeners with the following code:
*
* <pre>ItemListener[] ils = (ItemListener[])(l.getListeners(ItemListener.class));
*
* If no such listeners exist, this method returns an empty array.
*
* @param listenerType the type of listeners requested; this parameter
* should specify an interface that descends from
* <code>java.util.EventListener
* @return an array of all objects registered as
* <code>FooListeners on this list,
* or an empty array if no such
* listeners have been added
* @exception ClassCastException if <code>listenerType
* doesn't specify a class or interface that implements
* <code>java.util.EventListener
*
* @see #getItemListeners
* @since 1.3
*/
public <T extends EventListener> T[] getListeners(Class listenerType) {
EventListener l = null;
if (listenerType == ActionListener.class) {
l = actionListener;
} else if (listenerType == ItemListener.class) {
l = itemListener;
} else {
return super.getListeners(listenerType);
}
return AWTEventMulticaster.getListeners(l, listenerType);
}
// REMIND: remove when filtering is done at lower level
boolean eventEnabled(AWTEvent e) {
switch(e.id) {
case ActionEvent.ACTION_PERFORMED:
if ((eventMask & AWTEvent.ACTION_EVENT_MASK) != 0 ||
actionListener != null) {
return true;
}
return false;
case ItemEvent.ITEM_STATE_CHANGED:
if ((eventMask & AWTEvent.ITEM_EVENT_MASK) != 0 ||
itemListener != null) {
return true;
}
return false;
default:
break;
}
return super.eventEnabled(e);
}
/**
* Processes events on this scrolling list. If an event is
* an instance of <code>ItemEvent, it invokes the
* <code>processItemEvent method. Else, if the
* event is an instance of <code>ActionEvent,
* it invokes <code>processActionEvent.
* If the event is not an item event or an action event,
* it invokes <code>processEvent on the superclass.
* <p>Note that if the event parameter is null
* the behavior is unspecified and may result in an
* exception.
*
* @param e the event
* @see java.awt.event.ActionEvent
* @see java.awt.event.ItemEvent
* @see #processActionEvent
* @see #processItemEvent
* @since JDK1.1
*/
protected void processEvent(AWTEvent e) {
if (e instanceof ItemEvent) {
processItemEvent((ItemEvent)e);
return;
} else if (e instanceof ActionEvent) {
processActionEvent((ActionEvent)e);
return;
}
super.processEvent(e);
}
/**
* Processes item events occurring on this list by
* dispatching them to any registered
* <code>ItemListener objects.
* <p>
* This method is not called unless item events are
* enabled for this component. Item events are enabled
* when one of the following occurs:
* <ul>
* <li>An ItemListener object is registered
* via <code>addItemListener.
* <li>Item events are enabled via enableEvents.
* </ul>
* <p>Note that if the event parameter is null
* the behavior is unspecified and may result in an
* exception.
*
* @param e the item event
* @see java.awt.event.ItemEvent
* @see java.awt.event.ItemListener
* @see #addItemListener
* @see java.awt.Component#enableEvents
* @since JDK1.1
*/
protected void processItemEvent(ItemEvent e) {
ItemListener listener = itemListener;
if (listener != null) {
listener.itemStateChanged(e);
}
}
/**
* Processes action events occurring on this component
* by dispatching them to any registered
* <code>ActionListener objects.
* <p>
* This method is not called unless action events are
* enabled for this component. Action events are enabled
* when one of the following occurs:
* <ul>
* <li>An ActionListener object is registered
* via <code>addActionListener.
* <li>Action events are enabled via enableEvents.
* </ul>
* <p>Note that if the event parameter is null
* the behavior is unspecified and may result in an
* exception.
*
* @param e the action event
* @see java.awt.event.ActionEvent
* @see java.awt.event.ActionListener
* @see #addActionListener
* @see java.awt.Component#enableEvents
* @since JDK1.1
*/
protected void processActionEvent(ActionEvent e) {
ActionListener listener = actionListener;
if (listener != null) {
listener.actionPerformed(e);
}
}
/**
* Returns the parameter string representing the state of this
* scrolling list. This string is useful for debugging.
* @return the parameter string of this scrolling list
*/
protected String paramString() {
return super.paramString() + ",selected=" + getSelectedItem();
}
/**
* @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.
*/
@Deprecated
public synchronized void delItems(int start, int end) {
for (int i = end; i >= start; i--) {
items.removeElementAt(i);
}
ListPeer peer = (ListPeer)this.peer;
if (peer != null) {
peer.delItems(start, end);
}
}
/*
* Serialization support. Since the value of the selected
* field isn't necessarily up to date, we sync it up with the
* peer before serializing.
*/
/**
* The <code>List component's
* Serialized Data Version.
*
* @serial
*/
private int listSerializedDataVersion = 1;
/**
* Writes default serializable fields to stream. Writes
* a list of serializable <code>ItemListeners
* and <code>ActionListeners as optional data.
* The non-serializable listeners are detected and
* no attempt is made to serialize them.
*
* @serialData <code>null terminated sequence of 0
* or more pairs; the pair consists of a <code>String
* and an <code>Object; the String
* indicates the type of object and is one of the
* following:
* <code>itemListenerK indicating an
* <code>ItemListener object;
* <code>actionListenerK indicating an
* <code>ActionListener object
*
* @param s the <code>ObjectOutputStream to write
* @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
* @see java.awt.Component#itemListenerK
* @see java.awt.Component#actionListenerK
* @see #readObject(ObjectInputStream)
*/
private void writeObject(ObjectOutputStream s)
throws IOException
{
synchronized (this) {
ListPeer peer = (ListPeer)this.peer;
if (peer != null) {
selected = peer.getSelectedIndexes();
}
}
s.defaultWriteObject();
AWTEventMulticaster.save(s, itemListenerK, itemListener);
AWTEventMulticaster.save(s, actionListenerK, actionListener);
s.writeObject(null);
}
/**
* Reads the <code>ObjectInputStream and if it
* isn't <code>null adds a listener to receive
* both item events and action events (as specified
* by the key stored in the stream) fired by the
* <code>List.
* Unrecognized keys or values will be ignored.
*
* @param s the <code>ObjectInputStream to write
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless returns
* <code>true
* @see #removeItemListener(ItemListener)
* @see #addItemListener(ItemListener)
* @see java.awt.GraphicsEnvironment#isHeadless
* @see #writeObject(ObjectOutputStream)
*/
private void readObject(ObjectInputStream s)
throws ClassNotFoundException, IOException, HeadlessException
{
GraphicsEnvironment.checkHeadless();
s.defaultReadObject();
Object keyOrNull;
while(null != (keyOrNull = s.readObject())) {
String key = ((String)keyOrNull).intern();
if (itemListenerK == key)
addItemListener((ItemListener)(s.readObject()));
else if (actionListenerK == key)
addActionListener((ActionListener)(s.readObject()));
else // skip value for unrecognized key
s.readObject();
}
}
/////////////////
// Accessibility support
////////////////
/**
* Gets the <code>AccessibleContext associated with this
* <code>List. For lists, the AccessibleContext
* takes the form of an <code>AccessibleAWTList.
* A new <code>AccessibleAWTList instance is created, if necessary.
*
* @return an <code>AccessibleAWTList that serves as the
* <code>AccessibleContext of this List
* @since 1.3
*/
public AccessibleContext getAccessibleContext() {
if (accessibleContext == null) {
accessibleContext = new AccessibleAWTList();
}
return accessibleContext;
}
/**
* This class implements accessibility support for the
* <code>List class. It provides an implementation of the
* Java Accessibility API appropriate to list user-interface elements.
* @since 1.3
*/
protected class AccessibleAWTList extends AccessibleAWTComponent
implements AccessibleSelection, ItemListener, ActionListener
{
/*
* JDK 1.3 serialVersionUID
*/
private static final long serialVersionUID = 7924617370136012829L;
public AccessibleAWTList() {
super();
List.this.addActionListener(this);
List.this.addItemListener(this);
}
public void actionPerformed(ActionEvent event) {
}
public void itemStateChanged(ItemEvent event) {
}
/**
* Get the state set of this object.
*
* @return an instance of AccessibleState containing the current state
* of the object
* @see AccessibleState
*/
public AccessibleStateSet getAccessibleStateSet() {
AccessibleStateSet states = super.getAccessibleStateSet();
if (List.this.isMultipleMode()) {
states.add(AccessibleState.MULTISELECTABLE);
}
return states;
}
/**
* Get the role of this object.
*
* @return an instance of AccessibleRole describing the role of the
* object
* @see AccessibleRole
*/
public AccessibleRole getAccessibleRole() {
return AccessibleRole.LIST;
}
/**
* Returns the Accessible child contained at the local coordinate
* Point, if one exists.
*
* @return the Accessible at the specified location, if it exists
*/
public Accessible getAccessibleAt(Point p) {
return null; // fredxFIXME Not implemented yet
}
/**
* Returns the number of accessible children in the object. If all
* of the children of this object implement Accessible, than this
* method should return the number of children of this object.
*
* @return the number of accessible children in the object.
*/
public int getAccessibleChildrenCount() {
return List.this.getItemCount();
}
/**
* Return the nth Accessible child of the object.
*
* @param i zero-based index of child
* @return the nth Accessible child of the object
*/
public Accessible getAccessibleChild(int i) {
synchronized(List.this) {
if (i >= List.this.getItemCount()) {
return null;
} else {
return new AccessibleAWTListChild(List.this, i);
}
}
}
/**
* Get the AccessibleSelection associated with this object. In the
* implementation of the Java Accessibility API for this class,
* return this object, which is responsible for implementing the
* AccessibleSelection interface on behalf of itself.
*
* @return this object
*/
public AccessibleSelection getAccessibleSelection() {
return this;
}
// AccessibleSelection methods
/**
* Returns the number of items currently selected.
* If no items are selected, the return value will be 0.
*
* @return the number of items currently selected.
*/
public int getAccessibleSelectionCount() {
return List.this.getSelectedIndexes().length;
}
/**
* Returns an Accessible representing the specified selected item
* in the object. If there isn't a selection, or there are
* fewer items selected than the integer passed in, the return
* value will be null.
*
* @param i the zero-based index of selected items
* @return an Accessible containing the selected item
*/
public Accessible getAccessibleSelection(int i) {
synchronized(List.this) {
int len = getAccessibleSelectionCount();
if (i < 0 || i >= len) {
return null;
} else {
return getAccessibleChild(List.this.getSelectedIndexes()[i]);
}
}
}
/**
* Returns true if the current child of this object is selected.
*
* @param i the zero-based index of the child in this Accessible
* object.
* @see AccessibleContext#getAccessibleChild
*/
public boolean isAccessibleChildSelected(int i) {
return List.this.isIndexSelected(i);
}
/**
* Adds the specified selected item in the object to the object's
* selection. If the object supports multiple selections,
* the specified item is added to any existing selection, otherwise
* it replaces any existing selection in the object. If the
* specified item is already selected, this method has no effect.
*
* @param i the zero-based index of selectable items
*/
public void addAccessibleSelection(int i) {
List.this.select(i);
}
/**
* Removes the specified selected item in the object from the object's
* selection. If the specified item isn't currently selected, this
* method has no effect.
*
* @param i the zero-based index of selectable items
*/
public void removeAccessibleSelection(int i) {
List.this.deselect(i);
}
/**
* Clears the selection in the object, so that nothing in the
* object is selected.
*/
public void clearAccessibleSelection() {
synchronized(List.this) {
int selectedIndexes[] = List.this.getSelectedIndexes();
if (selectedIndexes == null)
return;
for (int i = selectedIndexes.length - 1; i >= 0; i--) {
List.this.deselect(selectedIndexes[i]);
}
}
}
/**
* Causes every selected item in the object to be selected
* if the object supports multiple selections.
*/
public void selectAllAccessibleSelection() {
synchronized(List.this) {
for (int i = List.this.getItemCount() - 1; i >= 0; i--) {
List.this.select(i);
}
}
}
/**
* This class implements accessibility support for
* List children. It provides an implementation of the
* Java Accessibility API appropriate to list children
* user-interface elements.
* @since 1.3
*/
protected class AccessibleAWTListChild extends AccessibleAWTComponent
implements Accessible
{
/*
* JDK 1.3 serialVersionUID
*/
private static final long serialVersionUID = 4412022926028300317L;
// [[[FIXME]]] need to finish implementing this!!!
private List parent;
private int indexInParent;
public AccessibleAWTListChild(List parent, int indexInParent) {
this.parent = parent;
this.setAccessibleParent(parent);
this.indexInParent = indexInParent;
}
//
// required Accessible methods
//
/**
* Gets the AccessibleContext for this object. In the
* implementation of the Java Accessibility API for this class,
* return this object, which acts as its own AccessibleContext.
*
* @return this object
*/
public AccessibleContext getAccessibleContext() {
return this;
}
//
// required AccessibleContext methods
//
/**
* Get the role of this object.
*
* @return an instance of AccessibleRole describing the role of
* the object
* @see AccessibleRole
*/
public AccessibleRole getAccessibleRole() {
return AccessibleRole.LIST_ITEM;
}
/**
* Get the state set of this object. The AccessibleStateSet of an
* object is composed of a set of unique AccessibleState's. A
* change in the AccessibleStateSet of an object will cause a
* PropertyChangeEvent to be fired for the
* ACCESSIBLE_STATE_PROPERTY property.
*
* @return an instance of AccessibleStateSet containing the
* current state set of the object
* @see AccessibleStateSet
* @see AccessibleState
* @see #addPropertyChangeListener
*/
public AccessibleStateSet getAccessibleStateSet() {
AccessibleStateSet states = super.getAccessibleStateSet();
if (parent.isIndexSelected(indexInParent)) {
states.add(AccessibleState.SELECTED);
}
return states;
}
/**
* Gets the locale of the component. If the component does not
* have a locale, then the locale of its parent is returned.
*
* @return This component's locale. If this component does not have
* a locale, the locale of its parent is returned.
*
* @exception IllegalComponentStateException
* If the Component does not have its own locale and has not yet
* been added to a containment hierarchy such that the locale can
* be determined from the containing parent.
*/
public Locale getLocale() {
return parent.getLocale();
}
/**
* Get the 0-based index of this object in its accessible parent.
*
* @return the 0-based index of this object in its parent; -1 if
* this object does not have an accessible parent.
*
* @see #getAccessibleParent
* @see #getAccessibleChildrenCount
* @see #getAccessibleChild
*/
public int getAccessibleIndexInParent() {
return indexInParent;
}
/**
* Returns the number of accessible children of the object.
*
* @return the number of accessible children of the object.
*/
public int getAccessibleChildrenCount() {
return 0; // list elements can't have children
}
/**
* Return the specified Accessible child of the object. The
* Accessible children of an Accessible object are zero-based,
* so the first child of an Accessible child is at index 0, the
* second child is at index 1, and so on.
*
* @param i zero-based index of child
* @return the Accessible child of the object
* @see #getAccessibleChildrenCount
*/
public Accessible getAccessibleChild(int i) {
return null; // list elements can't have children
}
//
// AccessibleComponent delegatation to parent List
//
/**
* Get the background color of this object.
*
* @return the background color, if supported, of the object;
* otherwise, null
* @see #setBackground
*/
public Color getBackground() {
return parent.getBackground();
}
/**
* Set the background color of this object.
*
* @param c the new Color for the background
* @see #setBackground
*/
public void setBackground(Color c) {
parent.setBackground(c);
}
/**
* Get the foreground color of this object.
*
* @return the foreground color, if supported, of the object;
* otherwise, null
* @see #setForeground
*/
public Color getForeground() {
return parent.getForeground();
}
/**
* Set the foreground color of this object.
*
* @param c the new Color for the foreground
* @see #getForeground
*/
public void setForeground(Color c) {
parent.setForeground(c);
}
/**
* Get the Cursor of this object.
*
* @return the Cursor, if supported, of the object; otherwise, null
* @see #setCursor
*/
public Cursor getCursor() {
return parent.getCursor();
}
/**
* Set the Cursor of this object.
* <p>
* The method may have no visual effect if the Java platform
* implementation and/or the native system do not support
* changing the mouse cursor shape.
* @param cursor the new Cursor for the object
* @see #getCursor
*/
public void setCursor(Cursor cursor) {
parent.setCursor(cursor);
}
/**
* Get the Font of this object.
*
* @return the Font,if supported, for the object; otherwise, null
* @see #setFont
*/
public Font getFont() {
return parent.getFont();
}
/**
* Set the Font of this object.
*
* @param f the new Font for the object
* @see #getFont
*/
public void setFont(Font f) {
parent.setFont(f);
}
/**
* Get the FontMetrics of this object.
*
* @param f the Font
* @return the FontMetrics, if supported, the object; otherwise, null
* @see #getFont
*/
public FontMetrics getFontMetrics(Font f) {
return parent.getFontMetrics(f);
}
/**
* Determine if the object is enabled. Objects that are enabled
* will also have the AccessibleState.ENABLED state set in their
* AccessibleStateSet.
*
* @return true if object is enabled; otherwise, false
* @see #setEnabled
* @see AccessibleContext#getAccessibleStateSet
* @see AccessibleState#ENABLED
* @see AccessibleStateSet
*/
public boolean isEnabled() {
return parent.isEnabled();
}
/**
* Set the enabled state of the object.
*
* @param b if true, enables this object; otherwise, disables it
* @see #isEnabled
*/
public void setEnabled(boolean b) {
parent.setEnabled(b);
}
/**
* Determine if the object is visible. Note: this means that the
* object intends to be visible; however, it may not be
* showing on the screen because one of the objects that this object
* is contained by is currently not visible. To determine if an
* object is showing on the screen, use isShowing().
* <p>Objects that are visible will also have the
* AccessibleState.VISIBLE state set in their AccessibleStateSet.
*
* @return true if object is visible; otherwise, false
* @see #setVisible
* @see AccessibleContext#getAccessibleStateSet
* @see AccessibleState#VISIBLE
* @see AccessibleStateSet
*/
public boolean isVisible() {
// [[[FIXME]]] needs to work like isShowing() below
return false;
// return parent.isVisible();
}
/**
* Set the visible state of the object.
*
* @param b if true, shows this object; otherwise, hides it
* @see #isVisible
*/
public void setVisible(boolean b) {
// [[[FIXME]]] should scroll to item to make it show!
parent.setVisible(b);
}
/**
* Determine if the object is showing. This is determined by
* checking the visibility of the object and visibility of the
* object ancestors.
* Note: this will return true even if the object is obscured
* by another (for example, it to object is underneath a menu
* that was pulled down).
*
* @return true if object is showing; otherwise, false
*/
public boolean isShowing() {
// [[[FIXME]]] only if it's showing!!!
return false;
// return parent.isShowing();
}
/**
* Checks whether the specified point is within this object's
* bounds, where the point's x and y coordinates are defined to
* be relative to the coordinate system of the object.
*
* @param p the Point relative to the coordinate system of the
* object
* @return true if object contains Point; otherwise false
* @see #getBounds
*/
public boolean contains(Point p) {
// [[[FIXME]]] - only if p is within the list element!!!
return false;
// return parent.contains(p);
}
/**
* Returns the location of the object on the screen.
*
* @return location of object on screen; null if this object
* is not on the screen
* @see #getBounds
* @see #getLocation
*/
public Point getLocationOnScreen() {
// [[[FIXME]]] sigh
return null;
}
/**
* Gets the location of the object relative to the parent in the
* form of a point specifying the object's top-left corner in the
* screen's coordinate space.
*
* @return An instance of Point representing the top-left corner of
* the objects's bounds in the coordinate space of the screen; null
* if this object or its parent are not on the screen
* @see #getBounds
* @see #getLocationOnScreen
*/
public Point getLocation() {
// [[[FIXME]]]
return null;
}
/**
* Sets the location of the object relative to the parent.
* @param p the new position for the top-left corner
* @see #getLocation
*/
public void setLocation(Point p) {
// [[[FIXME]]] maybe - can simply return as no-op
}
/**
* Gets the bounds of this object in the form of a Rectangle object.
* The bounds specify this object's width, height, and location
* relative to its parent.
*
* @return A rectangle indicating this component's bounds; null if
* this object is not on the screen.
* @see #contains
*/
public Rectangle getBounds() {
// [[[FIXME]]]
return null;
}
/**
* Sets the bounds of this object in the form of a Rectangle
* object. The bounds specify this object's width, height, and
* location relative to its parent.
*
* @param r rectangle indicating this component's bounds
* @see #getBounds
*/
public void setBounds(Rectangle r) {
// no-op; not supported
}
/**
* Returns the size of this object in the form of a Dimension
* object. The height field of the Dimension object contains this
* objects's height, and the width field of the Dimension object
* contains this object's width.
*
* @return A Dimension object that indicates the size of this
* component; null if this object is not on the screen
* @see #setSize
*/
public Dimension getSize() {
// [[[FIXME]]]
return null;
}
/**
* Resizes this object so that it has width and height.
*
* @param d - The dimension specifying the new size of the object.
* @see #getSize
*/
public void setSize(Dimension d) {
// not supported; no-op
}
/**
* Returns the <code>Accessible child, if one exists,
* contained at the local coordinate <code>Point.
*
* @param p the point relative to the coordinate system of this
* object
* @return the <code>Accessible, if it exists,
* at the specified location; otherwise <code>null
*/
public Accessible getAccessibleAt(Point p) {
return null; // object cannot have children!
}
/**
* Returns whether this object can accept focus or not. Objects
* that can accept focus will also have the
* <code>AccessibleState.FOCUSABLE state set in their
* <code>AccessibleStateSet.
*
* @return true if object can accept focus; otherwise false
* @see AccessibleContext#getAccessibleStateSet
* @see AccessibleState#FOCUSABLE
* @see AccessibleState#FOCUSED
* @see AccessibleStateSet
*/
public boolean isFocusTraversable() {
return false; // list element cannot receive focus!
}
/**
* Requests focus for this object. If this object cannot accept
* focus, nothing will happen. Otherwise, the object will attempt
* to take focus.
* @see #isFocusTraversable
*/
public void requestFocus() {
// nothing to do; a no-op
}
/**
* Adds the specified focus listener to receive focus events from
* this component.
*
* @param l the focus listener
* @see #removeFocusListener
*/
public void addFocusListener(FocusListener l) {
// nothing to do; a no-op
}
/**
* Removes the specified focus listener so it no longer receives
* focus events from this component.
*
* @param l the focus listener
* @see #addFocusListener
*/
public void removeFocusListener(FocusListener l) {
// nothing to do; a no-op
}
} // inner class AccessibleAWTListChild
} // inner class AccessibleAWTList
}
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