2 Write a JAVA program to read a number from user and then f

 2. Write a JAVA program to read a number from user  and then find out all prime numbers up to that number.  For Example, if user enters 10, then your program should show: The prime number up to 10 are: 2, 3, 5, 7  if user enters 0, then your program should show: The prime number up to 10 are: 2, 3, 5, 7, 11, 13, 17, 19  

Solution

PrimeNumbers.java

import java.util.Scanner;

public class PrimeNumbers {

  
   public static void main(String[] args) {
       Scanner scan = new Scanner(System.in);
       System.out.println(\"Please enter n value : \");
       int n = scan.nextInt();
       displayPrimeNumbers(n);
   }
   public static void displayPrimeNumbers(int n){
       int num =0;
       String s=\"\";
       System.out.println(\"The prime number up to \"+n+\" are:\");
       for(int i=2; i<n && num < n ; i++){
           int counter=0;   
   for(num =i; num>=1; num--)
       {
   if(i%num==0)
       {
          counter = counter + 1;
       }
       }
       if (counter == 2)
       {
           s = s + i +\", \";
       }
       }
       System.out.println(s.substring(0, s.length()-2));
   }
}

Output:

Please enter n value :
20
The prime number up to 20 are:
2, 3, 5, 7, 11, 13, 17, 19

Please enter n value :
10
The prime number up to 10 are:
2, 3, 5, 7