Computing hash codes : hashCode « Class Definition « Java Tutorial

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import java.util.Arrays;

 * Utilities for easily computing hash codes. The algorithm should generally produce good distributions for use in hash-based
 * containers or collections, but as expected does always result in repeatable hash codes given the inputs.
 * @author Randall Hauch
public class HashCode {

    // Prime number used in improving distribution: 1,000,003
    private static final int PRIME = 103;

     * Compute a combined hash code from the supplied objects. This method always returns 0 if no objects are supplied.
     * @param objects the objects that should be used to compute the hash code
     * @return the hash code
    public static int compute( Object... objects ) {
        return compute(0, objects);

     * Compute a combined hash code from the supplied objects using the supplied seed.
     * @param seed a value upon which the hash code will be based; may be 0
     * @param objects the objects that should be used to compute the hash code
     * @return the hash code
    protected static int compute( int seed, Object... objects ) {
        if (objects == null || objects.length == 0) {
            return seed * HashCode.PRIME;
        // Compute the hash code for all of the objects ...
        int hc = seed;
        for (Object object : objects) {
            hc = HashCode.PRIME * hc;
            if (object instanceof byte[]) {
                hc += Arrays.hashCode((byte[])object);
            } else if (object instanceof boolean[]) {
                hc += Arrays.hashCode((boolean[])object);
            } else if (object instanceof short[]) {
                hc += Arrays.hashCode((short[])object);
            } else if (object instanceof int[]) {
                hc += Arrays.hashCode((int[])object);
            } else if (object instanceof long[]) {
                hc += Arrays.hashCode((long[])object);
            } else if (object instanceof float[]) {
                hc += Arrays.hashCode((float[])object);
            } else if (object instanceof double[]) {
                hc += Arrays.hashCode((double[])object);
            } else if (object instanceof char[]) {
                hc += Arrays.hashCode((char[])object);
            } else if (object instanceof Object[]) {
                hc += Arrays.hashCode((Object[])object);
            } else if (object != null) {
                hc += object.hashCode();
        return hc;


5.34.1.Implement hashCode using commons-lang
5.34.2.Comparing Object Values Using Hash Codes
5.34.3.Get the identity hash codes
5.34.4.Null Safe Hash Code
5.34.5.Secure Hash
5.34.6.Get hash code for primitive data types
5.34.7.A very efficient java hash algorithm, based on the BuzHash algoritm
5.34.8.Computing hash codes
5.34.9.Returns an integer hash code representing the given double array value.