Help! Task: Ask for int, check if primenumber, print answer. Loop until forced to shut (ESC if using .showInputDialog())

Hi,

I have an assignment to make a program that keeps asking for input, checks if input is prime, and prints result, looping through this until forced to stop. Psuedocode i have written is(not good a pseudocode...):

• Ask user for a whole number. (ie. String prime = showInputDialog("Int please: ");)
• convert number to int (int maybePrime = Integer.parseInt(prime)
• Check if int is a prime.
• If maybePrime is a prime, print "is prime" (ie. showMessageDialog(null, "Is prime"; && System.out.println("Is a prime");)
• if maybePrime is not prime, print "is not prime" (ie. showMessageDialog(null, "Is not prime"; && System.out.println("Is not a prime");)) -Ask user for int.
• Loop until program is forced to shut. (ie. if using .showInputDialog(), stop program when ESC is pressed)

How would the actual formula for the prime number go? I know there is no exact formula for finding primes (if you have one, get ready to be famous!), but lets say i want to check numbers from 1-50. Been looking on the web for ages not finding a good answer to implement to Java while running it in a loop.

Hope someone can help me out here. if not, maybe this is a brain twister for some of the more experienced coder to have fun trying.

Regards Chris