/*
 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
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 *
 *
 *
 *
 */
package java.awt;

import java.awt.event.KeyEvent;
import sun.awt.AppContext;
import java.awt.event.InputEvent;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.StringTokenizer;
import java.io.Serializable;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Modifier;
import java.lang.reflect.Field;

/**
 * An <code>AWTKeyStroke</code> represents a key action on the
 * keyboard, or equivalent input device. <code>AWTKeyStroke</code>s
 * can correspond to only a press or release of a
 * particular key, just as <code>KEY_PRESSED</code> and
 * <code>KEY_RELEASED</code> <code>KeyEvent</code>s do;
 * alternately, they can correspond to typing a specific Java character, just
 * as <code>KEY_TYPED</code> <code>KeyEvent</code>s do.
 * In all cases, <code>AWTKeyStroke</code>s can specify modifiers
 * (alt, shift, control, meta, altGraph, or a combination thereof) which must be present
 * during the action for an exact match.
 * <p>
 * <code>AWTKeyStrokes</code> are immutable, and are intended
 * to be unique. Client code should never create an
 * <code>AWTKeyStroke</code> on its own, but should instead use
 * a variant of <code>getAWTKeyStroke</code>. Client use of these factory
 * methods allows the <code>AWTKeyStroke</code> implementation
 * to cache and share instances efficiently.
 *
 * @see #getAWTKeyStroke
 *
 * @author Arnaud Weber
 * @author David Mendenhall
 * @since 1.4
 */
public class AWTKeyStroke implements Serializable {
 static final long serialVersionUID = -6430539691155161871L;

 private static Map<String, Integer> modifierKeywords;
 /**
 * Associates VK_XXX (as a String) with code (as Integer). This is
 * done to avoid the overhead of the reflective call to find the
 * constant.
 */
 private static VKCollection vks;

 //A key for the collection of AWTKeyStrokes within AppContext.
 private static Object APP_CONTEXT_CACHE_KEY = new Object();
 //A key withing the cache
 private static AWTKeyStroke APP_CONTEXT_KEYSTROKE_KEY = new AWTKeyStroke();

 /*
 * Reads keystroke class from AppContext and if null, puts there the
 * AWTKeyStroke class.
 * Must be called under locked AWTKeyStro
 */
 private static Class<AWTKeyStroke> getAWTKeyStrokeClass() {
 Class<AWTKeyStroke> clazz = (Class)AppContext.getAppContext().get(AWTKeyStroke.class);
 if (clazz == null) {
 clazz = AWTKeyStroke.class;
 AppContext.getAppContext().put(AWTKeyStroke.class, AWTKeyStroke.class);
 }
 return clazz;
 }

 private char keyChar = KeyEvent.CHAR_UNDEFINED;
 private int keyCode = KeyEvent.VK_UNDEFINED;
 private int modifiers;
 private boolean onKeyRelease;

 static {
 /* ensure that the necessary native libraries are loaded */
 Toolkit.loadLibraries();
 }

 /**
 * Constructs an <code>AWTKeyStroke</code> with default values.
 * The default values used are:
 * <table border="1" summary="AWTKeyStroke default values">
 * <tr><th>Property</th><th>Default Value</th></tr>
 * <tr>
 * <td>Key Char</td>
 * <td><code>KeyEvent.CHAR_UNDEFINED</code></td>
 * </tr>
 * <tr>
 * <td>Key Code</td>
 * <td><code>KeyEvent.VK_UNDEFINED</code></td>
 * </tr>
 * <tr>
 * <td>Modifiers</td>
 * <td>none</td>
 * </tr>
 * <tr>
 * <td>On key release?</td>
 * <td><code>false</code></td>
 * </tr>
 * </table>
 *
 * <code>AWTKeyStroke</code>s should not be constructed
 * by client code. Use a variant of <code>getAWTKeyStroke</code>
 * instead.
 *
 * @see #getAWTKeyStroke
 */
 protected AWTKeyStroke() {
 }

 /**
 * Constructs an <code>AWTKeyStroke</code> with the specified
 * values. <code>AWTKeyStroke</code>s should not be constructed
 * by client code. Use a variant of <code>getAWTKeyStroke</code>
 * instead.
 *
 * @param keyChar the character value for a keyboard key
 * @param keyCode the key code for this <code>AWTKeyStroke</code>
 * @param modifiers a bitwise-ored combination of any modifiers
 * @param onKeyRelease <code>true</code> if this
 * <code>AWTKeyStroke</code> corresponds
 * to a key release; <code>false</code> otherwise
 * @see #getAWTKeyStroke
 */
 protected AWTKeyStroke(char keyChar, int keyCode, int modifiers,
 boolean onKeyRelease) {
 this.keyChar = keyChar;
 this.keyCode = keyCode;
 this.modifiers = modifiers;
 this.onKeyRelease = onKeyRelease;
 }

 /**
 * Registers a new class which the factory methods in
 * <code>AWTKeyStroke</code> will use when generating new
 * instances of <code>AWTKeyStroke</code>s. After invoking this
 * method, the factory methods will return instances of the specified
 * Class. The specified Class must be either <code>AWTKeyStroke</code>
 * or derived from <code>AWTKeyStroke</code>, and it must have a
 * no-arg constructor. The constructor can be of any accessibility,
 * including <code>private</code>. This operation
 * flushes the current <code>AWTKeyStroke</code> cache.
 *
 * @param subclass the new Class of which the factory methods should create
 * instances
 * @throws IllegalArgumentException if subclass is <code>null</code>,
 * or if subclass does not have a no-arg constructor
 * @throws ClassCastException if subclass is not
 * <code>AWTKeyStroke</code>, or a class derived from
 * <code>AWTKeyStroke</code>
 */
 protected static void registerSubclass(Class<?> subclass) {
 if (subclass == null) {
 throw new IllegalArgumentException("subclass cannot be null");
 }
 synchronized (AWTKeyStroke.class) {
 Class<AWTKeyStroke> keyStrokeClass = (Class)AppContext.getAppContext().get(AWTKeyStroke.class);
 if (keyStrokeClass != null && keyStrokeClass.equals(subclass)){
 // Already registered
 return;
 }
 }
 if (!AWTKeyStroke.class.isAssignableFrom(subclass)) {
 throw new ClassCastException("subclass is not derived from AWTKeyStroke");
 }

 Constructor ctor = getCtor(subclass);

 String couldNotInstantiate = "subclass could not be instantiated";

 if (ctor == null) {
 throw new IllegalArgumentException(couldNotInstantiate);
 }
 try {
 AWTKeyStroke stroke = (AWTKeyStroke)ctor.newInstance((Object[]) null);
 if (stroke == null) {
 throw new IllegalArgumentException(couldNotInstantiate);
 }
 } catch (NoSuchMethodError e) {
 throw new IllegalArgumentException(couldNotInstantiate);
 } catch (ExceptionInInitializerError e) {
 throw new IllegalArgumentException(couldNotInstantiate);
 } catch (InstantiationException e) {
 throw new IllegalArgumentException(couldNotInstantiate);
 } catch (IllegalAccessException e) {
 throw new IllegalArgumentException(couldNotInstantiate);
 } catch (InvocationTargetException e) {
 throw new IllegalArgumentException(couldNotInstantiate);
 }

 synchronized (AWTKeyStroke.class) {
 AppContext.getAppContext().put(AWTKeyStroke.class, subclass);
 AppContext.getAppContext().remove(APP_CONTEXT_CACHE_KEY);
 AppContext.getAppContext().remove(APP_CONTEXT_KEYSTROKE_KEY);
 }
 }

 /* returns noarg Constructor for class with accessible flag. No security
 threat as accessible flag is set only for this Constructor object,
 not for Class constructor.
 */
 private static Constructor getCtor(final Class clazz)
 {
 Constructor ctor = AccessController.doPrivileged(new PrivilegedAction<Constructor>() {
 public Constructor run() {
 try {
 Constructor ctor = clazz.getDeclaredConstructor((Class[]) null);
 if (ctor != null) {
 ctor.setAccessible(true);
 }
 return ctor;
 } catch (SecurityException e) {
 } catch (NoSuchMethodException e) {
 }
 return null;
 }
 });
 return (Constructor)ctor;
 }

 private static synchronized AWTKeyStroke getCachedStroke
 (char keyChar, int keyCode, int modifiers, boolean onKeyRelease)
 {
 Map<AWTKeyStroke, AWTKeyStroke> cache = (Map)AppContext.getAppContext().get(APP_CONTEXT_CACHE_KEY);
 AWTKeyStroke cacheKey = (AWTKeyStroke)AppContext.getAppContext().get(APP_CONTEXT_KEYSTROKE_KEY);

 if (cache == null) {
 cache = new HashMap<>();
 AppContext.getAppContext().put(APP_CONTEXT_CACHE_KEY, cache);
 }

 if (cacheKey == null) {
 try {
 Class<AWTKeyStroke> clazz = getAWTKeyStrokeClass();
 cacheKey = (AWTKeyStroke)getCtor(clazz).newInstance((Object[]) null);
 AppContext.getAppContext().put(APP_CONTEXT_KEYSTROKE_KEY, cacheKey);
 } catch (InstantiationException e) {
 assert(false);
 } catch (IllegalAccessException e) {
 assert(false);
 } catch (InvocationTargetException e) {
 assert(false);
 }
 }
 cacheKey.keyChar = keyChar;
 cacheKey.keyCode = keyCode;
 cacheKey.modifiers = mapNewModifiers(mapOldModifiers(modifiers));
 cacheKey.onKeyRelease = onKeyRelease;

 AWTKeyStroke stroke = (AWTKeyStroke)cache.get(cacheKey);
 if (stroke == null) {
 stroke = cacheKey;
 cache.put(stroke, stroke);
 AppContext.getAppContext().remove(APP_CONTEXT_KEYSTROKE_KEY);
 }
 return stroke;
 }

 /**
 * Returns a shared instance of an <code>AWTKeyStroke</code>
 * that represents a <code>KEY_TYPED</code> event for the
 * specified character.
 *
 * @param keyChar the character value for a keyboard key
 * @return an <code>AWTKeyStroke</code> object for that key
 */
 public static AWTKeyStroke getAWTKeyStroke(char keyChar) {
 return getCachedStroke(keyChar, KeyEvent.VK_UNDEFINED, 0, false);
 }

 /**
 * Returns a shared instance of an {@code AWTKeyStroke}
 * that represents a {@code KEY_TYPED} event for the
 * specified Character object and a set of modifiers. Note
 * that the first parameter is of type Character rather than
 * char. This is to avoid inadvertent clashes with
 * calls to <code>getAWTKeyStroke(int keyCode, int modifiers)</code>.
 *
 * The modifiers consist of any combination of following:<ul>
 * <li>java.awt.event.InputEvent.SHIFT_DOWN_MASK
 * <li>java.awt.event.InputEvent.CTRL_DOWN_MASK
 * <li>java.awt.event.InputEvent.META_DOWN_MASK
 * <li>java.awt.event.InputEvent.ALT_DOWN_MASK
 * <li>java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK
 * </ul>
 * The old modifiers listed below also can be used, but they are
 * mapped to _DOWN_ modifiers. <ul>
 * <li>java.awt.event.InputEvent.SHIFT_MASK
 * <li>java.awt.event.InputEvent.CTRL_MASK
 * <li>java.awt.event.InputEvent.META_MASK
 * <li>java.awt.event.InputEvent.ALT_MASK
 * <li>java.awt.event.InputEvent.ALT_GRAPH_MASK
 * </ul>
 * also can be used, but they are mapped to _DOWN_ modifiers.
 *
 * Since these numbers are all different powers of two, any combination of
 * them is an integer in which each bit represents a different modifier
 * key. Use 0 to specify no modifiers.
 *
 * @param keyChar the Character object for a keyboard character
 * @param modifiers a bitwise-ored combination of any modifiers
 * @return an <code>AWTKeyStroke</code> object for that key
 * @throws IllegalArgumentException if <code>keyChar</code> is
 * <code>null</code>
 *
 * @see java.awt.event.InputEvent
 */
 public static AWTKeyStroke getAWTKeyStroke(Character keyChar, int modifiers)
 {
 if (keyChar == null) {
 throw new IllegalArgumentException("keyChar cannot be null");
 }
 return getCachedStroke(keyChar.charValue(), KeyEvent.VK_UNDEFINED,
 modifiers, false);
 }

 /**
 * Returns a shared instance of an <code>AWTKeyStroke</code>,
 * given a numeric key code and a set of modifiers, specifying
 * whether the key is activated when it is pressed or released.
 * <p>
 * The "virtual key" constants defined in
 * <code>java.awt.event.KeyEvent</code> can be
 * used to specify the key code. For example:<ul>
 * <li><code>java.awt.event.KeyEvent.VK_ENTER</code>
 * <li><code>java.awt.event.KeyEvent.VK_TAB</code>
 * <li><code>java.awt.event.KeyEvent.VK_SPACE</code>
 * </ul>
 * Alternatively, the key code may be obtained by calling
 * <code>java.awt.event.KeyEvent.getExtendedKeyCodeForChar</code>.
 *
 * The modifiers consist of any combination of:<ul>
 * <li>java.awt.event.InputEvent.SHIFT_DOWN_MASK
 * <li>java.awt.event.InputEvent.CTRL_DOWN_MASK
 * <li>java.awt.event.InputEvent.META_DOWN_MASK
 * <li>java.awt.event.InputEvent.ALT_DOWN_MASK
 * <li>java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK
 * </ul>
 * The old modifiers <ul>
 * <li>java.awt.event.InputEvent.SHIFT_MASK
 * <li>java.awt.event.InputEvent.CTRL_MASK
 * <li>java.awt.event.InputEvent.META_MASK
 * <li>java.awt.event.InputEvent.ALT_MASK
 * <li>java.awt.event.InputEvent.ALT_GRAPH_MASK
 * </ul>
 * also can be used, but they are mapped to _DOWN_ modifiers.
 *
 * Since these numbers are all different powers of two, any combination of
 * them is an integer in which each bit represents a different modifier
 * key. Use 0 to specify no modifiers.
 *
 * @param keyCode an int specifying the numeric code for a keyboard key
 * @param modifiers a bitwise-ored combination of any modifiers
 * @param onKeyRelease <code>true</code> if the <code>AWTKeyStroke</code>
 * should represent a key release; <code>false</code> otherwise
 * @return an AWTKeyStroke object for that key
 *
 * @see java.awt.event.KeyEvent
 * @see java.awt.event.InputEvent
 */
 public static AWTKeyStroke getAWTKeyStroke(int keyCode, int modifiers,
 boolean onKeyRelease) {
 return getCachedStroke(KeyEvent.CHAR_UNDEFINED, keyCode, modifiers,
 onKeyRelease);
 }

 /**
 * Returns a shared instance of an <code>AWTKeyStroke</code>,
 * given a numeric key code and a set of modifiers. The returned
 * <code>AWTKeyStroke</code> will correspond to a key press.
 * <p>
 * The "virtual key" constants defined in
 * <code>java.awt.event.KeyEvent</code> can be
 * used to specify the key code. For example:<ul>
 * <li><code>java.awt.event.KeyEvent.VK_ENTER</code>
 * <li><code>java.awt.event.KeyEvent.VK_TAB</code>
 * <li><code>java.awt.event.KeyEvent.VK_SPACE</code>
 * </ul>
 * The modifiers consist of any combination of:<ul>
 * <li>java.awt.event.InputEvent.SHIFT_DOWN_MASK
 * <li>java.awt.event.InputEvent.CTRL_DOWN_MASK
 * <li>java.awt.event.InputEvent.META_DOWN_MASK
 * <li>java.awt.event.InputEvent.ALT_DOWN_MASK
 * <li>java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK
 * </ul>
 * The old modifiers <ul>
 * <li>java.awt.event.InputEvent.SHIFT_MASK
 * <li>java.awt.event.InputEvent.CTRL_MASK
 * <li>java.awt.event.InputEvent.META_MASK
 * <li>java.awt.event.InputEvent.ALT_MASK
 * <li>java.awt.event.InputEvent.ALT_GRAPH_MASK
 * </ul>
 * also can be used, but they are mapped to _DOWN_ modifiers.
 *
 * Since these numbers are all different powers of two, any combination of
 * them is an integer in which each bit represents a different modifier
 * key. Use 0 to specify no modifiers.
 *
 * @param keyCode an int specifying the numeric code for a keyboard key
 * @param modifiers a bitwise-ored combination of any modifiers
 * @return an <code>AWTKeyStroke</code> object for that key
 *
 * @see java.awt.event.KeyEvent
 * @see java.awt.event.InputEvent
 */
 public static AWTKeyStroke getAWTKeyStroke(int keyCode, int modifiers) {
 return getCachedStroke(KeyEvent.CHAR_UNDEFINED, keyCode, modifiers,
 false);
 }

 /**
 * Returns an <code>AWTKeyStroke</code> which represents the
 * stroke which generated a given <code>KeyEvent</code>.
 * <p>
 * This method obtains the keyChar from a <code>KeyTyped</code>
 * event, and the keyCode from a <code>KeyPressed</code> or
 * <code>KeyReleased</code> event. The <code>KeyEvent</code> modifiers are
 * obtained for all three types of <code>KeyEvent</code>.
 *
 * @param anEvent the <code>KeyEvent</code> from which to
 * obtain the <code>AWTKeyStroke</code>
 * @throws NullPointerException if <code>anEvent</code> is null
 * @return the <code>AWTKeyStroke</code> that precipitated the event
 */
 public static AWTKeyStroke getAWTKeyStrokeForEvent(KeyEvent anEvent) {
 int id = anEvent.getID();
 switch(id) {
 case KeyEvent.KEY_PRESSED:
 case KeyEvent.KEY_RELEASED:
 return getCachedStroke(KeyEvent.CHAR_UNDEFINED,
 anEvent.getKeyCode(),
 anEvent.getModifiers(),
 (id == KeyEvent.KEY_RELEASED));
 case KeyEvent.KEY_TYPED:
 return getCachedStroke(anEvent.getKeyChar(),
 KeyEvent.VK_UNDEFINED,
 anEvent.getModifiers(),
 false);
 default:
 // Invalid ID for this KeyEvent
 return null;
 }
 }

 /**
 * Parses a string and returns an <code>AWTKeyStroke</code>.
 * The string must have the following syntax:
 * <pre>
 * &lt;modifiers&gt;* (&lt;typedID&gt; | &lt;pressedReleasedID&gt;)
 *
 * modifiers := shift | control | ctrl | meta | alt | altGraph
 * typedID := typed &lt;typedKey&gt;
 * typedKey := string of length 1 giving Unicode character.
 * pressedReleasedID := (pressed | released) key
 * key := KeyEvent key code name, i.e. the name following "VK_".
 * </pre>
 * If typed, pressed or released is not specified, pressed is assumed. Here
 * are some examples:
 * <pre>
 * "INSERT" =&gt; getAWTKeyStroke(KeyEvent.VK_INSERT, 0);
 * "control DELETE" =&gt; getAWTKeyStroke(KeyEvent.VK_DELETE, InputEvent.CTRL_MASK);
 * "alt shift X" =&gt; getAWTKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK);
 * "alt shift released X" =&gt; getAWTKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK, true);
 * "typed a" =&gt; getAWTKeyStroke('a');
 * </pre>
 *
 * @param s a String formatted as described above
 * @return an <code>AWTKeyStroke</code> object for that String
 * @throws IllegalArgumentException if <code>s</code> is <code>null</code>,
 * or is formatted incorrectly
 */
 public static AWTKeyStroke getAWTKeyStroke(String s) {
 if (s == null) {
 throw new IllegalArgumentException("String cannot be null");
 }

 final String errmsg = "String formatted incorrectly";

 StringTokenizer st = new StringTokenizer(s, " ");

 int mask = 0;
 boolean released = false;
 boolean typed = false;
 boolean pressed = false;

 synchronized (AWTKeyStroke.class) {
 if (modifierKeywords == null) {
 Map<String, Integer> uninitializedMap = new HashMap<>(8, 1.0f);
 uninitializedMap.put("shift",
 Integer.valueOf(InputEvent.SHIFT_DOWN_MASK
 |InputEvent.SHIFT_MASK));
 uninitializedMap.put("control",
 Integer.valueOf(InputEvent.CTRL_DOWN_MASK
 |InputEvent.CTRL_MASK));
 uninitializedMap.put("ctrl",
 Integer.valueOf(InputEvent.CTRL_DOWN_MASK
 |InputEvent.CTRL_MASK));
 uninitializedMap.put("meta",
 Integer.valueOf(InputEvent.META_DOWN_MASK
 |InputEvent.META_MASK));
 uninitializedMap.put("alt",
 Integer.valueOf(InputEvent.ALT_DOWN_MASK
 |InputEvent.ALT_MASK));
 uninitializedMap.put("altGraph",
 Integer.valueOf(InputEvent.ALT_GRAPH_DOWN_MASK
 |InputEvent.ALT_GRAPH_MASK));
 uninitializedMap.put("button1",
 Integer.valueOf(InputEvent.BUTTON1_DOWN_MASK));
 uninitializedMap.put("button2",
 Integer.valueOf(InputEvent.BUTTON2_DOWN_MASK));
 uninitializedMap.put("button3",
 Integer.valueOf(InputEvent.BUTTON3_DOWN_MASK));
 modifierKeywords =
 Collections.synchronizedMap(uninitializedMap);
 }
 }

 int count = st.countTokens();

 for (int i = 1; i <= count; i++) {
 String token = st.nextToken();

 if (typed) {
 if (token.length() != 1 || i != count) {
 throw new IllegalArgumentException(errmsg);
 }
 return getCachedStroke(token.charAt(0), KeyEvent.VK_UNDEFINED,
 mask, false);
 }

 if (pressed || released || i == count) {
 if (i != count) {
 throw new IllegalArgumentException(errmsg);
 }

 String keyCodeName = "VK_" + token;
 int keyCode = getVKValue(keyCodeName);

 return getCachedStroke(KeyEvent.CHAR_UNDEFINED, keyCode,
 mask, released);
 }

 if (token.equals("released")) {
 released = true;
 continue;
 }
 if (token.equals("pressed")) {
 pressed = true;
 continue;
 }
 if (token.equals("typed")) {
 typed = true;
 continue;
 }

 Integer tokenMask = (Integer)modifierKeywords.get(token);
 if (tokenMask != null) {
 mask |= tokenMask.intValue();
 } else {
 throw new IllegalArgumentException(errmsg);
 }
 }

 throw new IllegalArgumentException(errmsg);
 }

 private static VKCollection getVKCollection() {
 if (vks == null) {
 vks = new VKCollection();
 }
 return vks;
 }
 /**
 * Returns the integer constant for the KeyEvent.VK field named
 * <code>key</code>. This will throw an
 * <code>IllegalArgumentException</code> if <code>key</code> is
 * not a valid constant.
 */
 private static int getVKValue(String key) {
 VKCollection vkCollect = getVKCollection();

 Integer value = vkCollect.findCode(key);

 if (value == null) {
 int keyCode = 0;
 final String errmsg = "String formatted incorrectly";

 try {
 keyCode = KeyEvent.class.getField(key).getInt(KeyEvent.class);
 } catch (NoSuchFieldException nsfe) {
 throw new IllegalArgumentException(errmsg);
 } catch (IllegalAccessException iae) {
 throw new IllegalArgumentException(errmsg);
 }
 value = Integer.valueOf(keyCode);
 vkCollect.put(key, value);
 }
 return value.intValue();
 }

 /**
 * Returns the character for this <code>AWTKeyStroke</code>.
 *
 * @return a char value
 * @see #getAWTKeyStroke(char)
 * @see KeyEvent#getKeyChar
 */
 public final char getKeyChar() {
 return keyChar;
 }

 /**
 * Returns the numeric key code for this <code>AWTKeyStroke</code>.
 *
 * @return an int containing the key code value
 * @see #getAWTKeyStroke(int,int)
 * @see KeyEvent#getKeyCode
 */
 public final int getKeyCode() {
 return keyCode;
 }

 /**
 * Returns the modifier keys for this <code>AWTKeyStroke</code>.
 *
 * @return an int containing the modifiers
 * @see #getAWTKeyStroke(int,int)
 */
 public final int getModifiers() {
 return modifiers;
 }

 /**
 * Returns whether this <code>AWTKeyStroke</code> represents a key release.
 *
 * @return <code>true</code> if this <code>AWTKeyStroke</code>
 * represents a key release; <code>false</code> otherwise
 * @see #getAWTKeyStroke(int,int,boolean)
 */
 public final boolean isOnKeyRelease() {
 return onKeyRelease;
 }

 /**
 * Returns the type of <code>KeyEvent</code> which corresponds to
 * this <code>AWTKeyStroke</code>.
 *
 * @return <code>KeyEvent.KEY_PRESSED</code>,
 * <code>KeyEvent.KEY_TYPED</code>,
 * or <code>KeyEvent.KEY_RELEASED</code>
 * @see java.awt.event.KeyEvent
 */
 public final int getKeyEventType() {
 if (keyCode == KeyEvent.VK_UNDEFINED) {
 return KeyEvent.KEY_TYPED;
 } else {
 return (onKeyRelease)
 ? KeyEvent.KEY_RELEASED
 : KeyEvent.KEY_PRESSED;
 }
 }

 /**
 * Returns a numeric value for this object that is likely to be unique,
 * making it a good choice as the index value in a hash table.
 *
 * @return an int that represents this object
 */
 public int hashCode() {
 return (((int)keyChar) + 1) * (2 * (keyCode + 1)) * (modifiers + 1) +
 (onKeyRelease ? 1 : 2);
 }

 /**
 * Returns true if this object is identical to the specified object.
 *
 * @param anObject the Object to compare this object to
 * @return true if the objects are identical
 */
 public final boolean equals(Object anObject) {
 if (anObject instanceof AWTKeyStroke) {
 AWTKeyStroke ks = (AWTKeyStroke)anObject;
 return (ks.keyChar == keyChar && ks.keyCode == keyCode &&
 ks.onKeyRelease == onKeyRelease &&
 ks.modifiers == modifiers);
 }
 return false;
 }

 /**
 * Returns a string that displays and identifies this object's properties.
 * The <code>String</code> returned by this method can be passed
 * as a parameter to <code>getAWTKeyStroke(String)</code> to produce
 * a key stroke equal to this key stroke.
 *
 * @return a String representation of this object
 * @see #getAWTKeyStroke(String)
 */
 public String toString() {
 if (keyCode == KeyEvent.VK_UNDEFINED) {
 return getModifiersText(modifiers) + "typed " + keyChar;
 } else {
 return getModifiersText(modifiers) +
 (onKeyRelease ? "released" : "pressed") + " " +
 getVKText(keyCode);
 }
 }

 static String getModifiersText(int modifiers) {
 StringBuilder buf = new StringBuilder();

 if ((modifiers & InputEvent.SHIFT_DOWN_MASK) != 0 ) {
 buf.append("shift ");
 }
 if ((modifiers & InputEvent.CTRL_DOWN_MASK) != 0 ) {
 buf.append("ctrl ");
 }
 if ((modifiers & InputEvent.META_DOWN_MASK) != 0 ) {
 buf.append("meta ");
 }
 if ((modifiers & InputEvent.ALT_DOWN_MASK) != 0 ) {
 buf.append("alt ");
 }
 if ((modifiers & InputEvent.ALT_GRAPH_DOWN_MASK) != 0 ) {
 buf.append("altGraph ");
 }
 if ((modifiers & InputEvent.BUTTON1_DOWN_MASK) != 0 ) {
 buf.append("button1 ");
 }
 if ((modifiers & InputEvent.BUTTON2_DOWN_MASK) != 0 ) {
 buf.append("button2 ");
 }
 if ((modifiers & InputEvent.BUTTON3_DOWN_MASK) != 0 ) {
 buf.append("button3 ");
 }

 return buf.toString();
 }

 static String getVKText(int keyCode) {
 VKCollection vkCollect = getVKCollection();
 Integer key = Integer.valueOf(keyCode);
 String name = vkCollect.findName(key);
 if (name != null) {
 return name.substring(3);
 }
 int expected_modifiers =
 (Modifier.PUBLIC | Modifier.STATIC | Modifier.FINAL);

 Field[] fields = KeyEvent.class.getDeclaredFields();
 for (int i = 0; i < fields.length; i++) {
 try {
 if (fields[i].getModifiers() == expected_modifiers
 && fields[i].getType() == Integer.TYPE
 && fields[i].getName().startsWith("VK_")
 && fields[i].getInt(KeyEvent.class) == keyCode)
 {
 name = fields[i].getName();
 vkCollect.put(name, key);
 return name.substring(3);
 }
 } catch (IllegalAccessException e) {
 assert(false);
 }
 }
 return "UNKNOWN";
 }

 /**
 * Returns a cached instance of <code>AWTKeyStroke</code> (or a subclass of
 * <code>AWTKeyStroke</code>) which is equal to this instance.
 *
 * @return a cached instance which is equal to this instance
 */
 protected Object readResolve() throws java.io.ObjectStreamException {
 synchronized (AWTKeyStroke.class) {
 if (getClass().equals(getAWTKeyStrokeClass())) {
 return getCachedStroke(keyChar, keyCode, modifiers, onKeyRelease);
 }
 }
 return this;
 }

 private static int mapOldModifiers(int modifiers) {
 if ((modifiers & InputEvent.SHIFT_MASK) != 0) {
 modifiers |= InputEvent.SHIFT_DOWN_MASK;
 }
 if ((modifiers & InputEvent.ALT_MASK) != 0) {
 modifiers |= InputEvent.ALT_DOWN_MASK;
 }
 if ((modifiers & InputEvent.ALT_GRAPH_MASK) != 0) {
 modifiers |= InputEvent.ALT_GRAPH_DOWN_MASK;
 }
 if ((modifiers & InputEvent.CTRL_MASK) != 0) {
 modifiers |= InputEvent.CTRL_DOWN_MASK;
 }
 if ((modifiers & InputEvent.META_MASK) != 0) {
 modifiers |= InputEvent.META_DOWN_MASK;
 }

 modifiers &= InputEvent.SHIFT_DOWN_MASK
 | InputEvent.ALT_DOWN_MASK
 | InputEvent.ALT_GRAPH_DOWN_MASK
 | InputEvent.CTRL_DOWN_MASK
 | InputEvent.META_DOWN_MASK
 | InputEvent.BUTTON1_DOWN_MASK
 | InputEvent.BUTTON2_DOWN_MASK
 | InputEvent.BUTTON3_DOWN_MASK;

 return modifiers;
 }

 private static int mapNewModifiers(int modifiers) {
 if ((modifiers & InputEvent.SHIFT_DOWN_MASK) != 0) {
 modifiers |= InputEvent.SHIFT_MASK;
 }
 if ((modifiers & InputEvent.ALT_DOWN_MASK) != 0) {
 modifiers |= InputEvent.ALT_MASK;
 }
 if ((modifiers & InputEvent.ALT_GRAPH_DOWN_MASK) != 0) {
 modifiers |= InputEvent.ALT_GRAPH_MASK;
 }
 if ((modifiers & InputEvent.CTRL_DOWN_MASK) != 0) {
 modifiers |= InputEvent.CTRL_MASK;
 }
 if ((modifiers & InputEvent.META_DOWN_MASK) != 0) {
 modifiers |= InputEvent.META_MASK;
 }

 return modifiers;
 }

}

class VKCollection {
 Map<Integer, String> code2name;
 Map<String, Integer> name2code;

 public VKCollection() {
 code2name = new HashMap<>();
 name2code = new HashMap<>();
 }

 public synchronized void put(String name, Integer code) {
 assert((name != null) && (code != null));
 assert(findName(code) == null);
 assert(findCode(name) == null);
 code2name.put(code, name);
 name2code.put(name, code);
 }

 public synchronized Integer findCode(String name) {
 assert(name != null);
 return (Integer)name2code.get(name);
 }

 public synchronized String findName(Integer code) {
 assert(code != null);
 return (String)code2name.get(code);
 }
}