Base converaion through recursion

This program can convert a decimal number to its binary, hexadecimal or octal number.

import java.util.*;
class MAIN
{  public  static final char vb[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
   public static String st="";
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
System.out.println("give the string");
int N;
int y;
N=in.nextInt();
System.out.println("in hexadecimal");
base(N,16);
System.out.println("back conversion");
y=Integer.parseInt(st);

System.out.println("in binary");
base(N,2);
System.out.println("in octal");
base(N,8);

}
public static void base(int n,int b)
{
if(n>=b)
{
base(n/b,b);
}
System.out.print(vb[n%b]);
}
}