java code hexToByte

    private static final String HEXINDEX = "0123456789abcdef          ABCDEF";

   public static byte[] hexToByte(String s) {
       int l = s.length() / 2;
       byte data[] = new byte[l];
       int j = 0;

       for (int i = 0; i < l; i++) {
           char c = s.charAt(j++);
           int n, b;

           n = HEXINDEX.indexOf(c);
           b = (n & 0xf) << 4;
           c = s.charAt(j++);
           n = HEXINDEX.indexOf(c);
           b += (n & 0xf);
           data[i] = (byte) b;
       }
       return data;
   }