key.java

JXTA&#8482 is a set of open, generalized peer-to-peer (P2P) protocols that allow any networked devi

/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xindice" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999-2001, The dbXML
 * Group, L.L.C., http://www.dbxmlgroup.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */
package net.jxta.impl.xindice.core.data;

/**
 * Key extends Value by providing a hash value for the Key.
 */
public final class Key extends Value {
    private int hash = 0;

    public Key(Value value) {
        super(value);
    }

    public Key(byte[] data) {
        super(data);
    }

    public Key(byte[] data, int pos, int len) {
        super(data, pos, len);
    }

    public Key(String data) {
        super(data);
    }

    // TODO: This has to be revisited
    private void calculateHash() {
        hash = 0;
        int pl = pos + len;

        for (int i = pos; i < pl; i++) {
            hash = (hash << 5) ^ data[i];
            hash = hash % 1234567891;
        }
        hash = Math.abs(hash);
    }

    public int getHash() {
        if (hash == 0) {
            calculateHash();
        }
        return hash;
    }

    @Override
    public boolean equals(Value value) {
        if (value instanceof Key) {
            Key key = (Key) value;

            return getHash() == key.getHash() && compareTo(key) == 0;
        } else {
            return super.equals(value);
        }
    }

    @Override
    public int hashCode() {
        return getHash();
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof Key) {
            return equals((Key) obj);
        } else {
            return super.equals(obj);
        }
    }
}