Zero instance enum

enum Util {
    /* No instances */;

    public static int clamp(int min, int max, int i) {
        return Math.min(Math.max(i, min), max);
    }

    // other utility methods...
}

Just as enum can be used for singletons (1 instance classes), it can be used for utility classes (0 instance classes). Just make sure to terminate the (empty) list of enum constants with a ;.

See the question http://stackoverflow.com/questions/25137490/zero-instance-enum-vs-private-constructors-for-preventing-instantiation for a discussion on pro’s and con’s compared to private constructors.