Java Object Hash hashCode(final Object o)

Description

hash Code

License

Apache License

Declaration

public static int hashCode(final Object o) 

Method Source Code

//package com.java2s;
/*//from   www.j ava 2s .  com
 * HashUtilities.java
 *
 * Copyright (c) 2012 Mike Strobel
 *
 * This source code is subject to terms and conditions of the Apache License, Version 2.0.
 * A copy of the license can be found in the License.html file at the root of this distribution.
 * By using this source code in any fashion, you are agreeing to be bound by the terms of the
 * Apache License, Version 2.0.
 *
 * You must not remove this notice, or any other, from this software.
 */

import java.util.Arrays;

public class Main {
    public static final int NullHashCode = 0x61E04917;
    private static final int CombinedHashOffset = 5;

    public static int hashCode(final Object o) {
        if (o == null) {
            return NullHashCode;
        }

        if (o.getClass().isArray()) {
            if (o instanceof Object[]) {
                return combineHashCodes((Object[]) o);
            }

            if (o instanceof byte[]) {
                return Arrays.hashCode((byte[]) o);
            }

            if (o instanceof short[]) {
                return Arrays.hashCode((short[]) o);
            }

            if (o instanceof int[]) {
                return Arrays.hashCode((int[]) o);
            }

            if (o instanceof long[]) {
                return Arrays.hashCode((long[]) o);
            }

            if (o instanceof char[]) {
                return Arrays.hashCode((char[]) o);
            }

            if (o instanceof float[]) {
                return Arrays.hashCode((float[]) o);
            }

            if (o instanceof double[]) {
                return Arrays.hashCode((double[]) o);
            }

            if (o instanceof boolean[]) {
                return Arrays.hashCode((boolean[]) o);
            }
        }

        return o.hashCode();
    }

    public static int combineHashCodes(final int... hashes) {
        int hash = 0;

        for (final int h : hashes) {
            hash <<= CombinedHashOffset;
            hash ^= h;
        }

        return hash;
    }

    public static int combineHashCodes(final Object... objects) {
        int hash = 0;

        for (final Object o : objects) {
            int entryHash = NullHashCode;

            if (o != null) {
                if (o instanceof Object[]) {
                    entryHash = combineHashCodes((Object[]) o);
                } else {
                    entryHash = hashCode(o);
                }
            }

            hash <<= CombinedHashOffset;
            hash ^= entryHash;
        }

        return hash;
    }

    public static int combineHashCodes(final int hash1, final int hash2) {
        return (hash1 << CombinedHashOffset) ^ hash2;
    }

    public static int combineHashCodes(final int hash1, final int hash2,
            final int hash3) {
        return (((hash1 << CombinedHashOffset) ^ hash2) << CombinedHashOffset)
                ^ hash3;
    }

    public static int combineHashCodes(final int hash1, final int hash2,
            final int hash3, final int hash4) {
        return (((((hash1 << CombinedHashOffset) ^ hash2) << CombinedHashOffset) ^ hash3) << CombinedHashOffset)
                ^ hash4;
    }

    public static int combineHashCodes(final int hash1, final int hash2,
            final int hash3, final int hash4, final int hash5) {

        return (((((((hash1 << CombinedHashOffset) ^ hash2) << CombinedHashOffset) ^ hash3) << CombinedHashOffset) ^ hash4) << CombinedHashOffset)
                ^ hash5;
    }

    public static int combineHashCodes(final int hash1, final int hash2,
            final int hash3, final int hash4, final int hash5,
            final int hash6) {

        return (((((((((hash1 << CombinedHashOffset) ^ hash2) << CombinedHashOffset) ^ hash3) << CombinedHashOffset) ^ hash4) << CombinedHashOffset) ^ hash5) << CombinedHashOffset)
                ^ hash6;
    }

    public static int combineHashCodes(final int hash1, final int hash2,
            final int hash3, final int hash4, final int hash5,
            final int hash6, final int hash7) {

        return (((((((((((hash1 << CombinedHashOffset) ^ hash2) << CombinedHashOffset) ^ hash3) << CombinedHashOffset) ^ hash4) << CombinedHashOffset) ^ hash5) << CombinedHashOffset) ^ hash6) << CombinedHashOffset)
                ^ hash7;
    }

    public static int combineHashCodes(final int hash1, final int hash2,
            final int hash3, final int hash4, final int hash5,
            final int hash6, final int hash7, final int hash8) {

        return (((((((((((((hash1 << CombinedHashOffset) ^ hash2) << CombinedHashOffset) ^ hash3) << CombinedHashOffset) ^ hash4) << CombinedHashOffset) ^ hash5) << CombinedHashOffset) ^ hash6) << CombinedHashOffset) ^ hash7) << CombinedHashOffset)
                ^ hash8;
    }

    public static int combineHashCodes(final Object o1, final Object o2) {
        return combineHashCodes(o1 == null ? NullHashCode : hashCode(o1),
                o2 == null ? NullHashCode : hashCode(o2));
    }

    public static int combineHashCodes(final Object o1, final Object o2,
            final Object o3) {
        return combineHashCodes(o1 == null ? NullHashCode : hashCode(o1),
                o2 == null ? NullHashCode : hashCode(o2),
                o3 == null ? NullHashCode : hashCode(o3));
    }

    public static int combineHashCodes(final Object o1, final Object o2,
            final Object o3, final Object o4) {
        return combineHashCodes(o1 == null ? NullHashCode : hashCode(o1),
                o2 == null ? NullHashCode : hashCode(o2),
                o3 == null ? NullHashCode : hashCode(o3),
                o4 == null ? NullHashCode : hashCode(o4));
    }

    public static int combineHashCodes(final Object o1, final Object o2,
            final Object o3, final Object o4, final Object o5) {

        return combineHashCodes(o1 == null ? NullHashCode : hashCode(o1),
                o2 == null ? NullHashCode : hashCode(o2),
                o3 == null ? NullHashCode : hashCode(o3),
                o4 == null ? NullHashCode : hashCode(o4),
                o5 == null ? NullHashCode : hashCode(o5));
    }

    public static int combineHashCodes(final Object o1, final Object o2,
            final Object o3, final Object o4, final Object o5,
            final Object o6) {

        return combineHashCodes(o1 == null ? NullHashCode : hashCode(o1),
                o2 == null ? NullHashCode : hashCode(o2),
                o3 == null ? NullHashCode : hashCode(o3),
                o4 == null ? NullHashCode : hashCode(o4),
                o5 == null ? NullHashCode : hashCode(o5),
                o6 == null ? NullHashCode : hashCode(o6));
    }

    public static int combineHashCodes(final Object o1, final Object o2,
            final Object o3, final Object o4, final Object o5,
            final Object o6, final Object o7) {

        return combineHashCodes(o1 == null ? NullHashCode : hashCode(o1),
                o2 == null ? NullHashCode : hashCode(o2),
                o3 == null ? NullHashCode : hashCode(o3),
                o4 == null ? NullHashCode : hashCode(o4),
                o5 == null ? NullHashCode : hashCode(o5),
                o6 == null ? NullHashCode : hashCode(o6),
                o7 == null ? NullHashCode : hashCode(o7));
    }

    public static int combineHashCodes(final Object o1, final Object o2,
            final Object o3, final Object o4, final Object o5,
            final Object o6, final Object o7, final Object o8) {

        return combineHashCodes(o1 == null ? NullHashCode : hashCode(o1),
                o2 == null ? NullHashCode : hashCode(o2),
                o3 == null ? NullHashCode : hashCode(o3),
                o4 == null ? NullHashCode : hashCode(o4),
                o5 == null ? NullHashCode : hashCode(o5),
                o6 == null ? NullHashCode : hashCode(o6),
                o7 == null ? NullHashCode : hashCode(o7),
                o8 == null ? NullHashCode : hashCode(o8));
    }
}

Related

1. deepHashCode(Object o)
2. getIdentityAsHex(Object object)
3. hash(Object o)
4. hash(Object... objects)
5. hash(Object... values)
6. hashCode(final Object... objects)
7. hashCode(final Object... objects)
8. hashCode(Object o)
9. hashCode(Object obj)