Find GCD of two numbers using Java

import java.io.*;
class gcd1
{
   public long gcd11(long a,long b)
   {
      if(b==0)
      return a;
      else
      return gcd11(b,a%b);
   }
}
public class GCD
{
   public static void main(String args[])throws IOException
   {
      gcd1 r=new gcd1();
      long a,b;
      String str;
      DataInputStream in= new DataInputStream(System.in);
      System.out.println("To get the GCD of two numbers.");
      System.out.println();
      System.out.print("Enter the value for A: ");
      str=in.readLine();
      a=Integer.parseInt(str);
      System.out.print("Enter the value for B: ");
      str=in.readLine();
      b=Integer.parseInt(str);
      long l=r.gcd11(a,b);
      System.out.println();
      System.out.println("The GCD of the number is: "+l);
   }
}