Java How To -Check if a Number Is Prime
Check if a Number Is Prime
A prime number is only divisible by 1 and itself.
To test if a number is prime, we try dividing it by every number from 2 up to its square root:
Example
int n = 29; // Number used to checkboolean isPrime = n > 1;for (int i = 2; i * i <= n; i++) { if (n % i == 0) { isPrime = false; break; }}System.out.println(n + (isPrime ? " is prime" : " is not prime"));Explanation: We start with the number29. Since 29 is greater than 1, the loop checks if it can be divided evenly by any number from 2 up to the square root of 29 (about 5.38). The numbers 2, 3, 4, and 5 do not divide 29 without a remainder, so the program concludes that29 is prime.
