recursiveAsal.java

import java.util.Scanner;

public class recursiveAsal {

        static boolean isPrime(int n, int i){
            // 0 and 1 are not prime numbers.
            if(n==0 || n==1){
                return false;
            }
            // 2 is prime number.
            if(n==2){
                return true;
            }
            else{
                // If the number has a divisor, it must be equal to 1 and itself. Otherwise the number is not prime.
                if(n%i==0){
                    if(i==1){
                        return isPrime(n,i+1);
                    }else if(n==i){
                        return true;
                    }else{
                        return false;
                    }
                } else{
                    return isPrime(n,i+1);
                }
            }
        }
        public static void main(String[] args) {
            Scanner inp = new Scanner(System.in);
            int n;
            System.out.print("Enter number : ");
            n=inp.nextInt();
            if(isPrime(n,1)){
                System.out.println(n + " is prime number.");
            }else {
                System.out.println(n + " is not prime number.");
            }
        }
    }