Returns a suitable hash code for the specified array. - Java Collection Framework

Java examples for Collection Framework:Array Element

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Description

Returns a suitable hash code for the specified array.

Demo Code


//package com.java2s;
import java.lang.reflect.Array;

public class Main {
    public static void main(String[] argv) throws Exception {
        Object array = "java2s.com";
        System.out.println(computeHashCode(array));
    }/*from  w  w w .  j ava  2s  .  co m*/

    /**
     * Returns a suitable hash code for the specified array. If the passed
     * object is <code>null</code>, <code>0</code> is returned.
     * It is allowed to pass an object that is not an array, in this case, 
     * the hash code of the object will be returned. Otherwise the hash code
     * will be based on the array elements. <code>null</code> elements are
     * allowed.
     * This method does not handle multidimensional arrays, i.e. if an
     * array contains another array, the hash code is based on identity.
     * @param array the array
     * @return a suitable hash code
     */
    public static int computeHashCode(Object array) {
        if (null == array)
            return 0;
        if (!array.getClass().isArray())
            return array.hashCode();
        int length = Array.getLength(array);
        int hashCode = 17;
        for (int ii = 0; ii < length; ii++) {
            Object value = Array.get(array, ii);
            if (null != value)
                hashCode = (31 * hashCode) + value.hashCode();
        }
        return hashCode;
    }
}

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