Welcome to the Ranch
Why have you got that for loop with no continuation condition? Why have you nested it inside a while loop? Why do you have a constructor allowing you to set the size of your array and then
test it against 100? You have a serious design flaw in the get(int) method; what happens if you have a 50-element array and look for no 60?
How are you calculating prime numbers? You ought to write it down on paper and get an algorithm working. Those three nested loops look very complicated to me, and suggest to me there is a better way to so that.