Java tutorial
/* * 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 * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing; import java.awt.AWTKeyStroke; import java.awt.event.KeyEvent; import sun.swing.SwingAccessor; /** * 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 * @since 1.2 */ @SuppressWarnings("serial") // Same-version serialization only public class KeyStroke extends AWTKeyStroke { /** * Serial Version ID. */ private static final long serialVersionUID = -9060180771037902530L; static { SwingAccessor.setKeyStrokeAccessor(new SwingAccessor.KeyStrokeAccessor() { @Override public KeyStroke create() { return new KeyStroke(); } }); } 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) { 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) { 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) { 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) { 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) { 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) { try { return (KeyStroke) getAWTKeyStroke(s); } catch (IllegalArgumentException e) { return null; } } } }