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| 1 | +/* | |
| 2 | + * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | +package sun.swing; | |
| 26 | + | |
| 27 | +import java.util.*; | |
| 28 | + | |
| 29 | +/** | |
| 30 | + * <b>WARNING:</b> This class is an implementation detail and is only | |
| 31 | + * public so that it can be used by two packages. You should NOT consider | |
| 32 | + * this public API. | |
| 33 | + * <p> | |
| 34 | + * <b>WARNING 2:</b> This is not a general purpose List implementation! It | |
| 35 | + * has a specific use and will not work correctly if you use it outside of | |
| 36 | + * its use. | |
| 37 | + * <p> | |
| 38 | + * A specialized ArrayList that caches its hashCode as well as overriding | |
| 39 | + * equals to avoid creating an Iterator. This class is useful in scenarios | |
| 40 | + * where the list won't change and you want to avoid the overhead of hashCode | |
| 41 | + * iterating through the elements invoking hashCode. This also assumes you'll | |
| 42 | + * only ever compare a BakedArrayList to another BakedArrayList. | |
| 43 | + * | |
| 44 | + * @author Scott Violet | |
| 45 | + */ | |
| 46 | +public class BakedArrayList extends ArrayList { | |
| 47 | + /** | |
| 48 | + * The cached hashCode. | |
| 49 | + */ | |
| 50 | + private int _hashCode; | |
| 51 | + | |
| 52 | + public BakedArrayList(int size) { | |
| 53 | + super(size); | |
| 54 | + } | |
| 55 | + | |
| 56 | + public BakedArrayList(java.util.List data) { | |
| 57 | + this(data.size()); | |
| 58 | + for (int counter = 0, max = data.size(); counter < max; counter++){ | |
| 59 | + add(data.get(counter)); | |
| 60 | + } | |
| 61 | + cacheHashCode(); | |
| 62 | + } | |
| 63 | + | |
| 64 | + /** | |
| 65 | + * Caches the hash code. It is assumed you won't modify the list, or that | |
| 66 | + * if you do you'll call cacheHashCode again. | |
| 67 | + */ | |
| 68 | + public void cacheHashCode() { | |
| 69 | + _hashCode = 1; | |
| 70 | + for (int counter = size() - 1; counter >= 0; counter--) { | |
| 71 | + _hashCode = 31 * _hashCode + get(counter).hashCode(); | |
| 72 | + } | |
| 73 | + } | |
| 74 | + | |
| 75 | + public int hashCode() { | |
| 76 | + return _hashCode; | |
| 77 | + } | |
| 78 | + | |
| 79 | + public boolean equals(Object o) { | |
| 80 | + BakedArrayList list = (BakedArrayList)o; | |
| 81 | + int size = size(); | |
| 82 | + | |
| 83 | + if (list.size() != size) { | |
| 84 | + return false; | |
| 85 | + } | |
| 86 | + while (size-- > 0) { | |
| 87 | + if (!get(size).equals(list.get(size))) { | |
| 88 | + return false; | |
| 89 | + } | |
| 90 | + } | |
| 91 | + return true; | |
| 92 | + } | |
| 93 | +} | |