How to randomize between given number in Java?

I'd like to know how to randomize between already given values.

let's say I want a number that's either '20', '30', or '70'. is there a way I can specify random values in rnd.nextInt() or do I have to use some workaround method?

tried to do it the following way,but it takes forever for the program to run (literally):

        int specNum;
        do {
            specNum = rnd.nextInt(51)+20;
        } while (specNum != 20 || specNum!= 30 || specNum != 70);