JDK14/Java14源码在线阅读
/*
* Copyright (c) 1995, 2019, 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.*;
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} 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:
*
* <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" style="margin: 7px 10px;">
* <p>
* In the picture, {@code "Green"} 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} components and the behavior of
* {@code setSize()/getSize()} is bound by
* such limitations.
* Native GUI {@code Choice} components' size are often bound by such
* attributes as font size and length of items contained within
* the {@code Choice}.
*
* @author Sami Shaio
* @author Arthur van Hoff
* @since 1.0
*/
public class Choice extends Component implements ItemSelectable, Accessible {
/**
* The items for the {@code Choice}.
* This can be a {@code null} value.
* @serial
* @see #add(String)
* @see #addItem(String)
* @see #getItem(int)
* @see #getItemCount()
* @see #insert(String, int)
* @see #remove(String)
*/
Vector<String> pItems;
/**
* The index of the current choice for this {@code Choice}
* 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;
static {
/* ensure that the necessary native libraries are loaded */
Toolkit.loadLibraries();
/* initialize JNI field and method ids */
if (!GraphicsEnvironment.isHeadless()) {
initIDs();
}
}
/**
* 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} 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} when the name is {@code null}.
*/
String constructComponentName() {
synchronized (Choice.class) {
return base + nameCounter++;
}
}
/**
* Creates the {@code Choice}'s peer. This peer allows us
* to change the look
* of the {@code Choice} without changing its functionality.
* @see java.awt.Component#getToolkit()
*/
public void addNotify() {
synchronized (getTreeLock()) {
if (peer == null)
peer = getComponentFactory().createChoice(this);
super.addNotify();
}
}
/**
* Returns the number of items in this {@code Choice} menu.
*
* @return the number of items in this {@code Choice} menu
* @see #getItem
* @since 1.1
*/
public int getItemCount() {
return countItems();
}
/**
* Returns the number of items in this {@code Choice} menu.
*
* @return the number of items in this {@code Choice} menu
* @deprecated As of JDK version 1.1,
* replaced by {@code getItemCount()}.
*/
@Deprecated
public int countItems() {
return pItems.size();
}
/**
* Gets the string at the specified index in this
* {@code Choice} menu.
*
* @param index the index at which to begin
* @return the item at the specified index
* @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 pItems.elementAt(index);
}
/**
* Adds an item to this {@code Choice} menu.
* @param item the item to be added
* @exception NullPointerException if the item's value is
* {@code null}
* @since 1.1
*/
public void add(String item) {
addItem(item);
}
/**
* Obsolete as of Java 2 platform v1.1. Please use the
* {@code add} method instead.
* <p>
* Adds an item to this {@code Choice} menu.
* @param item the item to be added
* @exception NullPointerException if the item's value is equal to
* {@code null}
*/
public void addItem(String item) {
synchronized (this) {
insertNoInvalidate(item, pItems.size());
}
// This could change the preferred size of the Component.
invalidateIfValid();
}
/**
* Inserts an item to this {@code Choice},
* but does not invalidate the {@code Choice}.
* 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}
*/
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.add(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} are shifted up by one to accommodate
* the new item. If {@code index} is greater than or
* equal to the number of items in this choice,
* {@code item} 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} 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.
invalidateIfValid();
}
/**
* Removes the first occurrence of {@code item}
* from the {@code Choice} 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} menu
* @exception IllegalArgumentException if the item doesn't
* exist in the choice menu
* @since 1.1
*/
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.
invalidateIfValid();
}
/**
* 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
* updated accordingly).
* @param position the position of the item
* @throws IndexOutOfBoundsException if the specified
* position is out of bounds
* @since 1.1
*/
public void remove(int position) {
synchronized (this) {
removeNoInvalidate(position);
}
// This could change the preferred size of the Component.
invalidateIfValid();
}
/**
* Removes an item from the {@code Choice} at the
* specified position, but does not invalidate the {@code Choice}.
* 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 1.1
*/
public void removeAll() {
synchronized (this) {
if (peer != null) {
((ChoicePeer)peer).removeAll();
}
pItems.removeAllElements();
selectedIndex = -1;
}
// This could change the preferred size of the Component.
invalidateIfValid();
}
/**
* 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}.
* @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} 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}. The only way to trigger an
* {@code ItemEvent} is by user interaction.
*
* @param pos the position 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} 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}. The only way to trigger an
* {@code ItemEvent} 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} menu. Item events are sent in response
* to user input, but not in response to calls to {@code select}.
* If l is {@code null}, no exception is thrown and no action
* is performed.
* <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
* >AWT Threading Issues</a> for details on AWT's threading model.
* @param l the item listener
* @see #removeItemListener
* @see #getItemListeners
* @see #select
* @see java.awt.event.ItemEvent
* @see java.awt.event.ItemListener
* @since 1.1
*/
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} menu.
* If l is {@code null}, no exception is thrown and no
* action is performed.
* <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
* >AWT Threading Issues</a> 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 1.1
*/
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}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 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><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} argument
* with a class literal, such as
* <code><em>Foo</em>Listener.class</code>.
* For example, you can query a
* {@code Choice c}
* 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}
* @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}
* 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<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}, it invokes the
* {@code processItemEvent} method. Otherwise, it calls its
* superclass's {@code processEvent} method.
* <p>Note that if the event parameter is {@code null}
* the behavior is unspecified and may result in an
* exception.
*
* @param e the event
* @see java.awt.event.ItemEvent
* @see #processItemEvent
* @since 1.1
*/
protected void processEvent(AWTEvent e) {
if (e instanceof ItemEvent) {
processItemEvent((ItemEvent)e);
return;
}
super.processEvent(e);
}
/**
* Processes item events occurring on this {@code Choice}
* menu 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 {@code ItemListener} object is registered
* via {@code addItemListener}.
* <li>Item events are enabled via {@code enableEvents}.
* </ul>
* <p>Note that if the event parameter is {@code 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(ItemListener)
* @see java.awt.Component#enableEvents
* @since 1.1
*/
protected void processItemEvent(ItemEvent e) {
ItemListener listener = itemListener;
if (listener != null) {
listener.itemStateChanged(e);
}
}
/**
* Returns a string representing the state of this {@code Choice}
* 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}.
*
* @return the parameter string of this {@code Choice} 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}
* as optional data. The non-serializable
* {@code ItemListeners} are detected and
* no attempt is made to serialize them.
*
* @param s the {@code ObjectOutputStream} to write
* @serialData {@code null} terminated sequence of 0
* or more pairs; the pair consists of a {@code String}
* and an {@code Object}; the {@code String} indicates
* the type of object and is one of the following:
* {@code itemListenerK} indicating an
* {@code ItemListener} 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} and if it
* isn't {@code null} adds a listener to receive
* item events fired by the {@code Choice} item.
* Unrecognized keys or values will be ignored.
*
* @param s the {@code ObjectInputStream} to read
* @exception HeadlessException if
* {@code GraphicsEnvironment.isHeadless} returns
* {@code true}
* @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();
}
}
/**
* Initialize JNI field and method IDs
*/
private static native void initIDs();
/////////////////
// Accessibility support
////////////////
/**
* Gets the {@code AccessibleContext} associated with this
* {@code Choice}. For {@code Choice} components,
* the {@code AccessibleContext} takes the form of an
* {@code AccessibleAWTChoice}. A new {@code AccessibleAWTChoice}
* instance is created if necessary.
*
* @return an {@code AccessibleAWTChoice} that serves as the
* {@code AccessibleContext} of this {@code Choice}
* @since 1.3
*/
public AccessibleContext getAccessibleContext() {
/**代码未完, 请加载全部代码(NowJava.com).**/
关注时代Java
关注时代Java