Java Collection Hash hashCodeDeep(Collection collection)

Description

Calculates the hashCode of a collection by summing up the hashcodes of all its members.

License

Open Source License

Parameter

Parameter	Description
collection	collection from which to extract hashCode

Return

sum of all member hashCodes

Declaration

public static int hashCodeDeep(Collection collection) 

Method Source Code

//package com.java2s;
/*/*from ww w . j  a  va  2 s .  c om*/
 * Copyright (c) 2012 Brown Bag Consulting.
 * This file is part of the ExpressUI project.
 * Author: Juan Osuna
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License Version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
 * Brown Bag Consulting, Brown Bag Consulting DISCLAIMS THE WARRANTY OF
 * NON INFRINGEMENT OF THIRD PARTY RIGHTS.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License.
 *
 * You can be released from the requirements of the license by purchasing
 * a commercial license. Buying such a license is mandatory as soon as you
 * develop commercial activities involving the ExpressUI software without
 * disclosing the source code of your own applications. These activities
 * include: offering paid services to customers as an ASP, providing
 * services from a web application, shipping ExpressUI with a closed
 * source product.
 *
 * For more information, please contact Brown Bag Consulting at this
 * address: juan@brownbagconsulting.com.
 */

import java.util.Collection;

public class Main {
    /**
     * Calculates the hashCode of a collection by summing up the hashcodes of all its members.
     * This assures that any two collections with exactly the same members have the same hashCode.
     *
     * @param collection collection from which to extract hashCode
     * @return sum of all member hashCodes
     */
    public static int hashCodeDeep(Collection collection) {
        int hashCode = 0;

        for (Object o : collection) {
            hashCode += o.hashCode();
        }

        return hashCode;
    }
}

Related

1. hashCode(Collection c)
2. hashCode(Collection collection)
3. hashCode(Collection collection)
4. hashCodeUnordered(Collection collection)