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 * Copyright (c) 1997, 2014, 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

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 */

package javax.swing;

import java.awt.AWTKeyStroke;

import java.awt.event.KeyEvent;

/**

 * A KeyStroke represents a key action on the keyboard, or equivalent input

 * device. KeyStrokes can correspond to only a press or release of a particular

 * key, just as KEY_PRESSED and KEY_RELEASED KeyEvents do; alternately, they

 * can correspond to typing a specific Java character, just as KEY_TYPED

 * KeyEvents do. In all cases, KeyStrokes can specify modifiers (alt, shift,

 * control, meta, altGraph, or a combination thereof) which must be present during the

 * action for an exact match.

 * <p>

 * KeyStrokes are used to define high-level (semantic) action events. Instead

 * of trapping every keystroke and throwing away the ones you are not

 * interested in, those keystrokes you care about automatically initiate

 * actions on the Components with which they are registered.

 * <p>

 * KeyStrokes are immutable, and are intended to be unique. Client code cannot

 * create a KeyStroke; a variant of <code>getKeyStroke</code> must be used

 * instead. These factory methods allow the KeyStroke implementation to cache

 * and share instances efficiently.

 * <p>

 * <strong>Warning:</strong>

 * Serialized objects of this class will not be compatible with

 * future Swing releases. The current serialization support is

 * appropriate for short term storage or RMI between applications running

 * the same version of Swing.  As of 1.4, support for long term storage

 * of all JavaBeans™

 * has been added to the <code>java.beans</code> package.

 * Please see {@link java.beans.XMLEncoder}.

 *

 * @see javax.swing.text.Keymap

 * @see #getKeyStroke

 *

 * @author Arnaud Weber

 * @author David Mendenhall

 */

@SuppressWarnings("serial") // Same-version serialization only

public class KeyStroke extends AWTKeyStroke {

    /**

     * Serial Version ID.

     */

    private static final long serialVersionUID = -9060180771037902530L;

    private KeyStroke() {

    }

    private KeyStroke(char keyChar, int keyCode, int modifiers,

                      boolean onKeyRelease) {

        super(keyChar, keyCode, modifiers, onKeyRelease);

    }

    /**

     * Returns a shared instance of a <code>KeyStroke</code>

     * that represents a <code>KEY_TYPED</code> event for the

     * specified character.

     *

     * @param keyChar the character value for a keyboard key

     * @return a KeyStroke object for that key

     */

    public static KeyStroke getKeyStroke(char keyChar) {

        synchronized (AWTKeyStroke.class) {

            registerSubclass(KeyStroke.class);

            return (KeyStroke)getAWTKeyStroke(keyChar);

        }

    }

    /**

     * Returns an instance of a KeyStroke, specifying whether the key is

     * considered to be activated when it is pressed or released. Unlike all

     * other factory methods in this class, the instances returned by this

     * method are not necessarily cached or shared.

     *

     * @param keyChar the character value for a keyboard key

     * @param onKeyRelease <code>true</code> if this KeyStroke corresponds to a

     *        key release; <code>false</code> otherwise.

     * @return a KeyStroke object for that key

     * @deprecated use getKeyStroke(char)

     */

    @Deprecated

    public static KeyStroke getKeyStroke(char keyChar, boolean onKeyRelease) {

        return new KeyStroke(keyChar, KeyEvent.VK_UNDEFINED, 0, onKeyRelease);

    }

    /**

     * Returns a shared instance of a {@code KeyStroke}

     * 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>getKeyStroke(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 KeyStroke object for that key

     * @throws IllegalArgumentException if keyChar is null

     *

     * @see java.awt.event.InputEvent

     * @since 1.3

     */

    public static KeyStroke getKeyStroke(Character keyChar, int modifiers) {

        synchronized (AWTKeyStroke.class) {

            registerSubclass(KeyStroke.class);

            return (KeyStroke)getAWTKeyStroke(keyChar, modifiers);

        }

    }

    /**

     * Returns a shared instance of a KeyStroke, 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 java.awt.event.KeyEvent can be

     * used to specify the key code. For example:<ul>

     * <li>java.awt.event.KeyEvent.VK_ENTER

     * <li>java.awt.event.KeyEvent.VK_TAB

     * <li>java.awt.event.KeyEvent.VK_SPACE

     * </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 KeyStroke should represent

     *        a key release; <code>false</code> otherwise.

     * @return a KeyStroke object for that key

     *

     * @see java.awt.event.KeyEvent

     * @see java.awt.event.InputEvent

     */

    public static KeyStroke getKeyStroke(int keyCode, int modifiers,

                                         boolean onKeyRelease) {

        synchronized (AWTKeyStroke.class) {

            registerSubclass(KeyStroke.class);

            return (KeyStroke)getAWTKeyStroke(keyCode, modifiers,

                                              onKeyRelease);

        }

    }

    /**

     * Returns a shared instance of a KeyStroke, given a numeric key code and a

     * set of modifiers. The returned KeyStroke will correspond to a key press.

     * <p>

     * The "virtual key" constants defined in java.awt.event.KeyEvent can be

     * used to specify the key code. For example:<ul>

     * <li>java.awt.event.KeyEvent.VK_ENTER

     * <li>java.awt.event.KeyEvent.VK_TAB

     * <li>java.awt.event.KeyEvent.VK_SPACE

     * </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

     * @return a KeyStroke object for that key

     *

     * @see java.awt.event.KeyEvent

     * @see java.awt.event.InputEvent

     */

    public static KeyStroke getKeyStroke(int keyCode, int modifiers) {

        synchronized (AWTKeyStroke.class) {

            registerSubclass(KeyStroke.class);

            return (KeyStroke)getAWTKeyStroke(keyCode, modifiers);

        }

    }

    /**

     * Returns a KeyStroke which represents the stroke which generated a given

     * KeyEvent.

     * <p>

     * This method obtains the keyChar from a KeyTyped event, and the keyCode

     * from a KeyPressed or KeyReleased event. The KeyEvent modifiers are

     * obtained for all three types of KeyEvent.

     *

     * @param anEvent the KeyEvent from which to obtain the KeyStroke

     * @throws NullPointerException if <code>anEvent</code> is null

     * @return the KeyStroke that precipitated the event

     */

    public static KeyStroke getKeyStrokeForEvent(KeyEvent anEvent) {

        synchronized (AWTKeyStroke.class) {

            registerSubclass(KeyStroke.class);

            return (KeyStroke)getAWTKeyStrokeForEvent(anEvent);

        }

    }

    /**

     * Parses a string and returns a <code>KeyStroke</code>.

     * The string must have the following syntax:

     * <pre>

     *    <modifiers>* (<typedID> | <pressedReleasedID>)

     *

     *    modifiers := shift | control | ctrl | meta | alt | altGraph

     *    typedID := typed <typedKey>

     *    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" => getKeyStroke(KeyEvent.VK_INSERT, 0);

     *     "control DELETE" => getKeyStroke(KeyEvent.VK_DELETE, InputEvent.CTRL_MASK);

     *     "alt shift X" => getKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK);

     *     "alt shift released X" => getKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK, true);

     *     "typed a" => getKeyStroke('a');

     * </pre>

     *

     * In order to maintain backward-compatibility, specifying a null String,

     * or a String which is formatted incorrectly, returns null.

     *

     * @param s a String formatted as described above

     * @return a KeyStroke object for that String, or null if the specified

     *         String is null, or is formatted incorrectly

     *

     * @see java.awt.event.KeyEvent

     */

    public static KeyStroke getKeyStroke(String s) {

        if (s == null || s.length() == 0) {

            return null;

        }

        synchronized (AWTKeyStroke.class) {

            registerSubclass(KeyStroke.class);

            try {

                return (KeyStroke)getAWTKeyStroke(s);

            } catch (IllegalArgumentException e) {

                return null;

            }

        }

    }

}