code: private static boolean tryEncoding(byte[] sig, byte b1, byte b2, byte b3,
              byte b4) {
          return ((sig[0] == b1) && (sig[1] == b2) && (sig[2] == b3) && (sig[3] == b4));
      }
docs: Check for a four-byte signature.
  <p>
  Utility routine for detectEncoding ().
  <p>
  Always looks for some part of "<?XML" in a specific encoding.
  
  @param sig
  The first four bytes read.
  @param b1
  The first byte of the signature
  @param b2
  The second byte of the signature
  @param b3
  The third byte of the signature
  @param b4
  The fourth byte of the signature
  @see #detectEncoding