/*
* @(#)Choice.java 1.89 04/05/18
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.awt;
import java.util.*;
import java.awt.peer.ChoicePeer;
import java.awt.event.*;
import java.util.EventListener;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import javax.accessibility.*;
/**
* The <code>Choice</code> class presents a pop-up menu of choices.
* The current choice is displayed as the title of the menu.
* <p>
* The following code example produces a pop-up menu:
* <p>
* <hr><blockquote><pre>
* Choice ColorChooser = new Choice();
* ColorChooser.add("Green");
* ColorChooser.add("Red");
* ColorChooser.add("Blue");
* </pre></blockquote><hr>
* <p>
* After this choice menu has been added to a panel,
* it appears as follows in its normal state:
* <p>
* <img src="doc-files/Choice-1.gif" alt="The following text describes the graphic"
* ALIGN=center HSPACE=10 VSPACE=7>
* <p>
* In the picture, <code>"Green"</code> is the current choice.
* Pushing the mouse button down on the object causes a menu to
* appear with the current choice highlighted.
* <p>
* Some native platforms do not support arbitrary resizing of
* <code>Choice</code> components and the behavior of
* <code>setSize()/getSize()</code> is bound by
* such limitations.
* Native GUI <code>Choice</code> components' size are often bound by such
* attributes as font size and length of items contained within
* the <code>Choice</code>.
* <p>
* @version 1.89 05/18/04
* @author Sami Shaio
* @author Arthur van Hoff
* @since JDK1.0
*/
public class Choice extends Component implements ItemSelectable, Accessible {
/**
* The items for the <code>Choice</code>.
* This can be a <code>null</code> value.
* @serial
* @see #add(String)
* @see #addItem(String)
* @see #getItem(int)
* @see #getItemCount()
* @see #insert(String, int)
* @see #remove(String)
*/
Vector pItems;
/**
* The index of the current choice for this <code>Choice</code>
* or -1 if nothing is selected.
* @serial
* @see #getSelectedItem()
* @see #select(int)
*/
int selectedIndex = -1;
transient ItemListener itemListener;
private static final String base = "choice";
private static int nameCounter = 0;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = -4075310674757313071L;
/**
* Creates a new choice menu. The menu initially has no items in it.
* <p>
* By default, the first item added to the choice menu becomes the
* selected item, until a different selection is made by the user
* by calling one of the <code>select</code> methods.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true
* @see java.awt.GraphicsEnvironment#isHeadless
* @see #select(int)
* @see #select(java.lang.String)
*/
public Choice() throws HeadlessException {
GraphicsEnvironment.checkHeadless();
pItems = new Vector();
}
/**
* Constructs a name for this component. Called by
* <code>getName</code> when the name is <code>null</code>.
*/
String constructComponentName() {
synchronized (getClass()) {
return base + nameCounter++;
}
}
/**
* Creates the <code>Choice</code>'s peer. This peer allows us
* to change the look
* of the <code>Choice</code> without changing its functionality.
* @see java.awt.Toolkit#createChoice(java.awt.Choice)
* @see java.awt.Component#getToolkit()
*/
public void addNotify() {
synchronized (getTreeLock()) {
if (peer == null)
peer = getToolkit().createChoice(this);
super.addNotify();
}
}
/**
* Returns the number of items in this <code>Choice</code> menu.
* @return the number of items in this <code>Choice</code> menu
* @see #getItem
* @since JDK1.1
*/
public int getItemCount() {
return countItems();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>getItemCount()</code>.
*/
@Deprecated
public int countItems() {
return pItems.size();
}
/**
* Gets the string at the specified index in this
* <code>Choice</code> menu.
* @param index the index at which to begin
* @see #getItemCount
*/
public String getItem(int index) {
return getItemImpl(index);
}
/*
* This is called by the native code, so client code can't
* be called on the toolkit thread.
*/
final String getItemImpl(int index) {
return (String)pItems.elementAt(index);
}
/**
* Adds an item to this <code>Choice</code> menu.
* @param item the item to be added
* @exception NullPointerException if the item's value is
* <code>null</code>
* @since JDK1.1
*/
public void add(String item) {
addItem(item);
}
/**
* Obsolete as of Java 2 platform v1.1. Please use the
* <code>add</code> method instead.
* <p>
* Adds an item to this <code>Choice</code> menu.
* @param item the item to be added
* @exception NullPointerException if the item's value is equal to
* <code>null</code>
*/
public void addItem(String item) {
synchronized (this) {
insertNoInvalidate(item, pItems.size());
}
// This could change the preferred size of the Component.
if (valid) {
invalidate();
}
}
/**
* Inserts an item to this <code>Choice</code>,
* but does not invalidate the <code>Choice</code>.
* Client methods must provide their own synchronization before
* invoking this method.
* @param item the item to be added
* @param index the new item position
* @exception NullPointerException if the item's value is equal to
* <code>null</code>
*/
private void insertNoInvalidate(String item, int index) {
if (item == null) {
throw new
NullPointerException("cannot add null item to Choice");
}
pItems.insertElementAt(item, index);
ChoicePeer peer = (ChoicePeer)this.peer;
if (peer != null) {
peer.addItem(item, index);
}
// no selection or selection shifted up
if (selectedIndex < 0 || selectedIndex >= index) {
select(0);
}
}
/**
* Inserts the item into this choice at the specified position.
* Existing items at an index greater than or equal to
* <code>index</code> are shifted up by one to accommodate
* the new item. If <code>index</code> is greater than or
* equal to the number of items in this choice,
* <code>item</code> is added to the end of this choice.
* <p>
* If the item is the first one being added to the choice,
* then the item becomes selected. Otherwise, if the
* selected item was one of the items shifted, the first
* item in the choice becomes the selected item. If the
* selected item was no among those shifted, it remains
* the selected item.
* @param item the non-<code>null</code> item to be inserted
* @param index the position at which the item should be inserted
* @exception IllegalArgumentException if index is less than 0
*/
public void insert(String item, int index) {
synchronized (this) {
if (index < 0) {
throw new IllegalArgumentException("index less than zero.");
}
/* if the index greater than item count, add item to the end */
index = Math.min(index, pItems.size());
insertNoInvalidate(item, index);
}
// This could change the preferred size of the Component.
if (valid) {
invalidate();
}
}
/**
* Removes the first occurrence of <code>item</code>
* from the <code>Choice</code> menu. If the item
* being removed is the currently selected item,
* then the first item in the choice becomes the
* selected item. Otherwise, the currently selected
* item remains selected (and the selected index is
* updated accordingly).
* @param item the item to remove from this <code>Choice</code> menu
* @exception IllegalArgumentException if the item doesn't
* exist in the choice menu
* @since JDK1.1
*/
public void remove(String item) {
synchronized (this) {
int index = pItems.indexOf(item);
if (index < 0) {
throw new IllegalArgumentException("item " + item +
" not found in choice");
} else {
removeNoInvalidate(index);
}
}
// This could change the preferred size of the Component.
if (valid) {
invalidate();
}
}
/**
* Removes an item from the choice menu
* at the specified position. If the item
* being removed is the currently selected item,
* then the first item in the choice becomes the
* selected item. Otherwise, the currently selected
* item remains selected (and the selected index is
* @param position the position of the item
* @throws IndexOutOfBoundsException if the specified
* position is out of bounds
* @since JDK1.1
*/
public void remove(int position) {
synchronized (this) {
removeNoInvalidate(position);
}
// This could change the preferred size of the Component.
if (valid) {
invalidate();
}
}
/**
* Removes an item from the <code>Choice</code> at the
* specified position, but does not invalidate the <code>Choice</code>.
* Client methods must provide their
* own synchronization before invoking this method.
* @param position the position of the item
*/
private void removeNoInvalidate(int position) {
pItems.removeElementAt(position);
ChoicePeer peer = (ChoicePeer)this.peer;
if (peer != null) {
peer.remove(position);
}
/* Adjust selectedIndex if selected item was removed. */
if (pItems.size() == 0) {
selectedIndex = -1;
} else if (selectedIndex == position) {
select(0);
} else if (selectedIndex > position) {
select(selectedIndex-1);
}
}
/**
* Removes all items from the choice menu.
* @see #remove
* @since JDK1.1
*/
public void removeAll() {
synchronized (this) {
if (peer != null) {
((ChoicePeer)peer).removeAll();
}
pItems.removeAllElements();
selectedIndex = -1;
}
// This could change the preferred size of the Component.
if (valid) {
invalidate();
}
}
/**
* Gets a representation of the current choice as a string.
* @return a string representation of the currently
* selected item in this choice menu
* @see #getSelectedIndex
*/
public synchronized String getSelectedItem() {
return (selectedIndex >= 0) ? getItem(selectedIndex) : null;
}
/**
* Returns an array (length 1) containing the currently selected
* item. If this choice has no items, returns <code>null</code>.
* @see ItemSelectable
*/
public synchronized Object[] getSelectedObjects() {
if (selectedIndex >= 0) {
Object[] items = new Object[1];
items[0] = getItem(selectedIndex);
return items;
}
return null;
}
/**
* Returns the index of the currently selected item.
* If nothing is selected, returns -1.
*
* @return the index of the currently selected item, or -1 if nothing
* is currently selected
* @see #getSelectedItem
*/
public int getSelectedIndex() {
return selectedIndex;
}
/**
* Sets the selected item in this <code>Choice</code> menu to be the
* item at the specified position.
*
* <p>Note that this method should be primarily used to
* initially select an item in this component.
* Programmatically calling this method will <i>not</i> trigger
* an <code>ItemEvent</code>. The only way to trigger an
* <code>ItemEvent</code> is by user interaction.
*
* @param pos the positon of the selected item
* @exception IllegalArgumentException if the specified
* position is greater than the
* number of items or less than zero
* @see #getSelectedItem
* @see #getSelectedIndex
*/
public synchronized void select(int pos) {
if ((pos >= pItems.size()) || (pos < 0)) {
throw new IllegalArgumentException("illegal Choice item position: " + pos);
}
if (pItems.size() > 0) {
selectedIndex = pos;
ChoicePeer peer = (ChoicePeer)this.peer;
if (peer != null) {
peer.select(pos);
}
}
}
/**
* Sets the selected item in this <code>Choice</code> menu
* to be the item whose name is equal to the specified string.
* If more than one item matches (is equal to) the specified string,
* the one with the smallest index is selected.
*
* <p>Note that this method should be primarily used to
* initially select an item in this component.
* Programmatically calling this method will <i>not</i> trigger
* an <code>ItemEvent</code>. The only way to trigger an
* <code>ItemEvent</code> is by user interaction.
*
* @param str the specified string
* @see #getSelectedItem
* @see #getSelectedIndex
*/
public synchronized void select(String str) {
int index = pItems.indexOf(str);
if (index >= 0) {
select(index);
}
}
/**
* Adds the specified item listener to receive item events from
* this <code>Choice</code> menu. Item events are sent in response
* to user input, but not in response to calls to <code>select</code>.
* If l is <code>null</code>, no exception is thrown and no action
* is performed.
* @param l the item listener
* @see #removeItemListener
* @see #getItemListeners
* @see #select
* @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 <code>Choice</code> menu.
* If l is <code>null</code>, no exception is thrown and no
* action is performed.
* @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 choice.
*
* @return all of this choice's <code>ItemListener</code>s
* 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 (ItemListener[])(getListeners(ItemListener.class));
}
/**
* Returns an array of all the objects currently registered
* as <code><em>Foo</em>Listener</code>s
* upon this <code>Choice</code>.
* <code><em>Foo</em>Listener</code>s are registered using the
* <code>add<em>Foo</em>Listener</code> method.
*
* <p>
* You can specify the <code>listenerType</code> argument
* with a class literal, such as
* <code><em>Foo</em>Listener.class</code>.
* For example, you can query a
* <code>Choice</code> <code>c</code>
* for its item listeners with the following code:
*
* <pre>ItemListener[] ils = (ItemListener[])(c.getListeners(ItemListener.class));</pre>
*
* 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</code>
* @return an array of all objects registered as
* <code><em>Foo</em>Listener</code>s on this choice,
* or an empty array if no such
* listeners have been added
* @exception ClassCastException if <code>listenerType</code>
* doesn't specify a class or interface that implements
* <code>java.util.EventListener</code>
*
* @see #getItemListeners
* @since 1.3
*/
public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
EventListener l = null;
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) {
if (e.id == ItemEvent.ITEM_STATE_CHANGED) {
if ((eventMask & AWTEvent.ITEM_EVENT_MASK) != 0 ||
itemListener != null) {
return true;
}
return false;
}
return super.eventEnabled(e);
}
/**
* Processes events on this choice. If the event is an
* instance of <code>ItemEvent</code>, it invokes the
* <code>processItemEvent</code> method. Otherwise, it calls its
* superclass's <code>processEvent</code> method.
* <p>Note that if the event parameter is <code>null</code>
* the behavior is unspecified and may result in an
* exception.
*
* @param e the event
* @see java.awt.event.ItemEvent
* @see #processItemEvent
* @since JDK1.1
*/
protected void processEvent(AWTEvent e) {
if (e instanceof ItemEvent) {
processItemEvent((ItemEvent)e);
return;
}
super.processEvent(e);
}
/**
* Processes item events occurring on this <code>Choice</code>
* menu by dispatching them to any registered
* <code>ItemListener</code> 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:
* <p><ul>
* <li>An <code>ItemListener</code> object is registered
* via <code>addItemListener</code>.
* <li>Item events are enabled via <code>enableEvents</code>.
* </ul>
* <p>Note that if the event parameter is <code>null</code>
* 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(ItemListener)
* @see java.awt.Component#enableEvents
* @since JDK1.1
*/
protected void processItemEvent(ItemEvent e) {
ItemListener listener = itemListener;
if (listener != null) {
listener.itemStateChanged(e);
}
}
/**
* Returns a string representing the state of this <code>Choice</code>
* menu. This method is intended to be used only for debugging purposes,
* and the content and format of the returned string may vary between
* implementations. The returned string may be empty but may not be
* <code>null</code>.
*
* @return the parameter string of this <code>Choice</code> menu
*/
protected String paramString() {
return super.paramString() + ",current=" + getSelectedItem();
}
/* Serialization support.
*/
/*
* Choice Serial Data Version.
* @serial
*/
private int choiceSerializedDataVersion = 1;
/**
* Writes default serializable fields to stream. Writes
* a list of serializable <code>ItemListeners</code>
* as optional data. The non-serializable
* <code>ItemListeners</code> are detected and
* no attempt is made to serialize them.
*
* @param s the <code>ObjectOutputStream</code> to write
* @serialData <code>null</code> terminated sequence of 0
* or more pairs; the pair consists of a <code>String</code>
* and an <code>Object</code>; the <code>String</code> indicates
* the type of object and is one of the following:
* <code>itemListenerK</code> indicating an
* <code>ItemListener</code> object
*
* @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
* @see java.awt.Component#itemListenerK
* @see #readObject(ObjectInputStream)
*/
private void writeObject(ObjectOutputStream s)
throws java.io.IOException
{
s.defaultWriteObject();
AWTEventMulticaster.save(s, itemListenerK, itemListener);
s.writeObject(null);
}
/**
* Reads the <code>ObjectInputStream</code> and if it
* isn't <code>null</code> adds a listener to receive
* item events fired by the <code>Choice</code> item.
* Unrecognized keys or values will be ignored.
*
* @param s the <code>ObjectInputStream</code> to read
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless</code> returns
* <code>true</code>
* @serial
* @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 // skip value for unrecognized key
s.readObject();
}
}
/////////////////
// Accessibility support
////////////////
/**
* Gets the <code>AccessibleContext</code> associated with this
* <code>Choice</code>. For <code>Choice</code> components,
* the <code>AccessibleContext</code> takes the form of an
* <code>AccessibleAWTChoice</code>. A new <code>AccessibleAWTChoice</code>
* instance is created if necessary.
*
* @return an <code>AccessibleAWTChoice</code> that serves as the
* <code>AccessibleContext</code> of this <code>Choice</code>
*/
public AccessibleContext getAccessibleContext() {
if (accessibleContext == null) {
accessibleContext = new AccessibleAWTChoice();
}
return accessibleContext;
}
/**
* This class implements accessibility support for the
* <code>Choice</code> class. It provides an implementation of the
* Java Accessibility API appropriate to choice user-interface elements.
*/
protected class AccessibleAWTChoice extends AccessibleAWTComponent
implements AccessibleAction
{
/*
* JDK 1.3 serialVersionUID
*/
private static final long serialVersionUID = 7175603582428509322L;
public AccessibleAWTChoice() {
super();
}
/**
* Get the AccessibleAction associated with this object. In the
* implementation of the Java Accessibility API for this class,
* return this object, which is responsible for implementing the
* AccessibleAction interface on behalf of itself.
*
* @return this object
* @see AccessibleAction
*/
public AccessibleAction getAccessibleAction() {
return this;
}
/**
* Get the role of this object.
*
* @return an instance of AccessibleRole describing the role of the
* object
* @see AccessibleRole
*/
public AccessibleRole getAccessibleRole() {
return AccessibleRole.COMBO_BOX;
}
/**
* Returns the number of accessible actions available in this object
* If there are more than one, the first one is considered the "default"
* action of the object.
*
* @return the zero-based number of Actions in this object
*/
public int getAccessibleActionCount() {
return 0; // To be fully implemented in a future release
}
/**
* Returns a description of the specified action of the object.
*
* @param i zero-based index of the actions
* @return a String description of the action
* @see #getAccessibleActionCount
*/
public String getAccessibleActionDescription(int i) {
return null; // To be fully implemented in a future release
}
/**
* Perform the specified Action on the object
*
* @param i zero-based index of actions
* @return true if the action was performed; otherwise false.
* @see #getAccessibleActionCount
*/
public boolean doAccessibleAction(int i) {
return false; // To be fully implemented in a future release
}
} // inner class AccessibleAWTChoice
}
|
