Java tutorial
/* * Copyright (c) 1999, 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.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; import java.util.HashMap; import java.util.Set; /** * {@code InputMap} provides a binding between an input event (currently only * {@code KeyStroke}s are used) and an {@code Object}. {@code InputMap}s are * usually used with an {@code ActionMap}, to determine an {@code Action} to * perform when a key is pressed. An {@code InputMap} can have a parent that * is searched for bindings not defined in the {@code InputMap}. * <p>As with {@code ActionMap} if you create a cycle, eg: * <pre> * InputMap am = new InputMap(); * InputMap bm = new InputMap(): * am.setParent(bm); * bm.setParent(am); * </pre> * some of the methods will cause a StackOverflowError to be thrown. * * @author Scott Violet * @since 1.3 */ @SuppressWarnings("serial") public class InputMap implements Serializable { /** Handles the mapping between KeyStroke and Action name. */ private transient ArrayTable arrayTable; /** Parent that handles any bindings we don't contain. */ private InputMap parent; /** * Creates an {@code InputMap} with no parent and no mappings. */ public InputMap() { } /** * Sets this {@code InputMap}'s parent. * * @param map the {@code InputMap} that is the parent of this one */ public void setParent(InputMap map) { this.parent = map; } /** * Gets this {@code InputMap}'s parent. * * @return map the {@code InputMap} that is the parent of this one, * or null if this {@code InputMap} has no parent */ public InputMap getParent() { return parent; } /** * Adds a binding for {@code keyStroke} to {@code actionMapKey}. * If {@code actionMapKey} is null, this removes the current binding * for {@code keyStroke}. * * @param keyStroke a {@code KeyStroke} * @param actionMapKey an action map key */ public void put(KeyStroke keyStroke, Object actionMapKey) { if (keyStroke == null) { return; } if (actionMapKey == null) { remove(keyStroke); } else { if (arrayTable == null) { arrayTable = new ArrayTable(); } arrayTable.put(keyStroke, actionMapKey); } } /** * Returns the binding for {@code keyStroke}, messaging the * parent {@code InputMap} if the binding is not locally defined. * * @param keyStroke the {@code KeyStroke} for which to get the binding * @return the binding for {@code keyStroke} */ public Object get(KeyStroke keyStroke) { if (arrayTable == null) { InputMap parent = getParent(); if (parent != null) { return parent.get(keyStroke); } return null; } Object value = arrayTable.get(keyStroke); if (value == null) { InputMap parent = getParent(); if (parent != null) { return parent.get(keyStroke); } } return value; } /** * Removes the binding for {@code key} from this {@code InputMap}. * * @param key the {@code KeyStroke} for which to remove the binding */ public void remove(KeyStroke key) { if (arrayTable != null) { arrayTable.remove(key); } } /** * Removes all the mappings from this {@code InputMap}. */ public void clear() { if (arrayTable != null) { arrayTable.clear(); } } /** * Returns the {@code KeyStroke}s that are bound in this {@code InputMap}. * * @return an array of the {@code KeyStroke}s that are bound in this * {@code InputMap} */ public KeyStroke[] keys() { if (arrayTable == null) { return null; } KeyStroke[] keys = new KeyStroke[arrayTable.size()]; arrayTable.getKeys(keys); return keys; } /** * Returns the number of {@code KeyStroke} bindings. * * @return the number of {@code KeyStroke} bindings */ public int size() { if (arrayTable == null) { return 0; } return arrayTable.size(); } /** * Returns an array of the {@code KeyStroke}s defined in this * {@code InputMap} and its parent. This differs from {@code keys()} * in that this method includes the keys defined in the parent. * * @return an array of the {@code KeyStroke}s defined in this * {@code InputMap} and its parent */ public KeyStroke[] allKeys() { int count = size(); InputMap parent = getParent(); if (count == 0) { if (parent != null) { return parent.allKeys(); } return keys(); } if (parent == null) { return keys(); } KeyStroke[] keys = keys(); KeyStroke[] pKeys = parent.allKeys(); if (pKeys == null) { return keys; } if (keys == null) { // Should only happen if size() != keys.length, which should only // happen if mutated from multiple threads (or a bogus subclass). return pKeys; } HashMap<KeyStroke, KeyStroke> keyMap = new HashMap<KeyStroke, KeyStroke>(); int counter; for (counter = keys.length - 1; counter >= 0; counter--) { keyMap.put(keys[counter], keys[counter]); } for (counter = pKeys.length - 1; counter >= 0; counter--) { keyMap.put(pKeys[counter], pKeys[counter]); } KeyStroke[] allKeys = new KeyStroke[keyMap.size()]; return keyMap.keySet().toArray(allKeys); } private void writeObject(ObjectOutputStream s) throws IOException { s.defaultWriteObject(); ArrayTable.writeArrayTable(s, arrayTable); } private void readObject(ObjectInputStream s) throws ClassNotFoundException, IOException { s.defaultReadObject(); for (int counter = s.readInt() - 1; counter >= 0; counter--) { put((KeyStroke) s.readObject(), s.readObject()); } } }