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Java example source code file (BakedArrayList.java)

This example Java source code file (BakedArrayList.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, bakedarraylist, util

The BakedArrayList.java Java example source code

/*
 * Copyright (c) 2003, 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 sun.swing;

import java.util.*;

/**
 * <b>WARNING: This class is an implementation detail and is only
 * public so that it can be used by two packages. You should NOT consider
 * this public API.
 * <p>
 * <b>WARNING 2: This is not a general purpose List implementation! It
 * has a specific use and will not work correctly if you use it outside of
 * its use.
 * <p>
 * A specialized ArrayList that caches its hashCode as well as overriding
 * equals to avoid creating an Iterator. This class is useful in scenarios
 * where the list won't change and you want to avoid the overhead of hashCode
 * iterating through the elements invoking hashCode. This also assumes you'll
 * only ever compare a BakedArrayList to another BakedArrayList.
 *
 * @author Scott Violet
 */
public class BakedArrayList extends ArrayList {
    /**
     * The cached hashCode.
     */
    private int _hashCode;

    public BakedArrayList(int size) {
        super(size);
    }

    public BakedArrayList(java.util.List data) {
        this(data.size());
        for (int counter = 0, max = data.size(); counter < max; counter++){
            add(data.get(counter));
        }
        cacheHashCode();
    }

    /**
     * Caches the hash code. It is assumed you won't modify the list, or that
     * if you do you'll call cacheHashCode again.
     */
    public void cacheHashCode() {
        _hashCode = 1;
        for (int counter = size() - 1; counter >= 0; counter--) {
            _hashCode = 31 * _hashCode + get(counter).hashCode();
        }
    }

    public int hashCode() {
        return _hashCode;
    }

    public boolean equals(Object o) {
        BakedArrayList list = (BakedArrayList)o;
        int size = size();

        if (list.size() != size) {
            return false;
        }
        while (size-- > 0) {
            if (!get(size).equals(list.get(size))) {
                return false;
            }
        }
        return true;
    }
}

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