Check Whether a Number is Prime or Not in Java | CodeTextPro

Prime or Not

In this program, you will learn the number is prime or not. Check the number is prime or not used for loop and while loop in java.

Example 1:

Program to Check Prime Number using a for loop

public class Prime {

    public static void main(String[] args) {

        int num = 29;
        boolean flag = false;
        for(int i = 2; i <= num/2; ++i)
        {
            // condition for nonprime number
            if(num % i == 0)
            {
                flag = true;
                break;
            }
        }

        if (!flag)
            System.out.println(num + " is a prime number.");
        else
            System.out.println(num + " is not a prime number.");
    }
}

Example 2: 

Program to Check Prime Number using a while loop
public class Prime {

    public static void main(String[] args) {

        int num = 33, i = 2;
        boolean flag = false;
        while(i <= num/2)
        {
            // condition for nonprime number
            if(num % i == 0)
            {
                flag = true;
                break;
            }

            ++i;
        }

        if (!flag)
            System.out.println(num + " is a prime number.");
        else
            System.out.println(num + " is not a prime number.");
    }
}