HashUtil

HashUtil.java

/**
 * Utility functions for hashing sets of values, based on the methods described in Ch. 3 of Effective Java
 */
public class HashUtil {

    public static int hash(boolean... args) {
        int result = 0;
        for (boolean arg : args) {
            result += 31 * result + (arg ? 1 : 0);
        }
        return result;
    }

    public static int hash(byte... args) {
        int result = 0;
        for (byte arg : args) {
            result += 31 * result + (int) arg;
        }
        return result;
    }

    public static int hash(char... args) {
        int result = 0;
        for (char arg : args) {
            result += 31 * result + (int) arg;
        }
        return result;
    }

    public static int hash(short... args) {
        int result = 0;
        for (short arg : args) {
            result += 31 * result + (int) arg;
        }
        return result;
    }

    public static int hash(int... args) {
        int result = 0;
        for (int arg : args) {
            result += 31 * result + arg;
        }
        return result;
    }

    public static int hash(long... args) {
        int result = 0;
        for (long arg : args) {
            result += 31 * result + (int) (arg ^ (arg >>> 32));
        }
        return result;
    }

    public static int hash(float... args) {
        int result = 0;
        for (float arg : args) {
            result += 31 * result + Float.floatToIntBits(arg);
        }
        return result;
    }

    public static int hash(double... args) {
        int result = 0;
        for (double arg : args) {
            long l = Double.doubleToLongBits(arg);
            result += 31 * result + (int) (l ^ (l >>> 32));
        }
        return result;
    }
}