GCD - Greatest Common Divisor in Java

import java.io.*;
class gcd1
{
public rational1(){}
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,x,y;
String str;
DataInputStream in= new DataInputStream(System.in);
System.out.println("Enter the value for A");
str=in.readLine();
a=Integer.parseInt(str);
System.out.println("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);
}
}