Introduction

In this demo I have used NetBeans IDE 8.2 for debugging purpose. But you can use any java programming language compiler as per your availability..

public class Javaexcercise
{
    public static void main(String[] args)
    {        
        for(int i = 1; i <= 20; i++)
        {
            if(isPrime(i))
            {
                System.out.print(i + "\n");
            }
        }    
    }
 
    public static boolean isPrime(int number)
    {
        for(int i = 2; i < number; i++)
    {
        if(number % i == 0)
            {
                return false;
            }
        }
 
        return true;
    }
}

Result