java program tutorial to check prime number
this java program tutorial uses command line argument to take input from user and convert string args into integer type using wrapper class integer cast method. then it uses a for loop to check that if the given number is divisible by any of the number between 2 to that number - 1 . if yes then it is not prime.
because the number is prime only if it is divisible by 1 and itself not any other number.