Java code for prime number

import java.util.*;

public class PrimeNumber

{

    public static void main(String[] args)

    {

        Scanner scanner = new Scanner(System.in);

        System.out.println("Please enter a number: ");

        int num = scanner.nextInt();

       

        if ( num < 2 ) {

            System.out.println("\n There are no Prime Numbers available");

            System.exit(0);

        }

        System.out.printf("\n The Prime Numbers from 1 to %d are: \n 2", num);

        PrimeNumber primeNum = new PrimeNumber();

        for (int i = 3; i <= num; i++) {

            if ( primeNum.isPrime(i) ) {

                System.out.print(", " + i);

            }

        }

    }

    // Method to check whether the number is prime or not

    public boolean isPrime(int num) {

        if ( num < 2 ) return false;

        for (int i = 2; i <= Math.sqrt(num); i++) {

            if ( num % i == 0 ) {

                return false;

            }

        }

        return true;

    }

}