convert binary to decimal in java using recursion

1// Convert binary to decimal in java using recursion
2public class BinaryToDecimalRecursion
3{
4   static int binaryToDecimal(String strBinary, int a) 
5   {
6      int size = strBinary.length(); 
7      if(a == size - 1)
8         return strBinary.charAt(a) - '0'; 
9      return((strBinary.charAt(a) - '0') << (size - a - 1)) + binaryToDecimal(strBinary, a + 1); 
10   }
11   public static void main(String[] args) 
12   {
13      String binaryNumber = "1111"; 
14      int n = 0;
15      System.out.println("Convert binary to decimal using recursion: ");
16      System.out.println(binaryToDecimal(binaryNumber, n));
17   }
18}