HashTool.java

/*
 * Copyright 2011-2013 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package kr.debop4j.core.tools;

/**
 * 해시코드를 생성합니다.
 *
 * @author 배성혁 ( sunghyouk.bae@gmail.com )
 * @since 12. 12. 27
 */
public class HashTool {

    /** The constant NULL_VALUE. */
    public static final int NULL_VALUE = 0;
    /** The constant ONE_VALUE. */
    public static final int ONE_VALUE = 1;
    /** The constant FACTOR. */
    public static final int FACTOR = 31;

    /**
     * 해시코드를 생성합니다.
     *
     * @param x 해시코드를 생성할 객체
     * @return 해시코드
     */
    private static int computeInternal(final Object x) {
        return (x != null) ? x.hashCode() : NULL_VALUE;
    }

    /**
     * 지정된 객체들의 Hash Code를 조합한 Hash Code를 생성합니다.
     *
     * @param objs 해쉬코드를 생성할 객체 배열
     * @return 조합된 Hash code
     */
    public static int compute(final Object... objs) {
        if (objs == null || objs.length == 0)
            return NULL_VALUE;

        int hash = NULL_VALUE;
        for (Object x : objs) {
            hash = hash * FACTOR + computeInternal(x);
        }
        return hash;
    }
}