Java program to print prime numbers upto n

import java.util.Scanner;
public class PrimeUptoN 
{
   public static void main(String[] args) 
   {
      Scanner sc = new Scanner(System.in);
      int a, b, number, counter;
      System.out.println("Please enter max number till which you want to print prime number: ");
      number = sc.nextInt();
      System.out.println("Prime numbers are: ");    
      for(a = 2; a <= number; a++)
      {
         counter = 0;
         for(b = 1; b <= a; b++)
         {
            if(a % b == 0)
            {
               counter++;
            }
         }     
         if(counter == 2)
         {
            System.out.print(a + " ");
         }
      }
      sc.close();
   }
}