Prime.java

Below is the syntax highlighted version of Prime.java from §2.1 Static Methods.

/******************************************************************************
 *  Compilation:  javac Prime.java
 *  Execution:    java Prime n
 *
 *  Test if n is prime.
 *
 ******************************************************************************/


public class Prime {

    // return true if n is prime, and false otherise
    public static boolean isPrime(int n) {

        // degenerate cases
        if (n < 2) return false;

        // test primality by brute force
        for (int i = 2; i * i <= n; i++) {
            if (n % i == 0) return false;
        }

        // no factors found
        return true;
    }

    // sample client program
    public static void main(String[] args) {
        int n = Integer.parseInt(args[0]);
        if (isPrime(n)) StdOut.println(n + " is prime.");
        else            StdOut.println(n + " is not prime.");
    }

}