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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   }

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