protected int fill(byte[] buffer,int offset,int count) throws IOException {
  if (inputStream == null)   return -1;
  try {
    return inputStream.read(buffer,offset,count);
  }
 catch (  IOException ex) {
    throw new IOException(ex);
  }
}

protected int fill ( byte [ ] buffer , int offset , int count ) throws IOException { if ( inputStream == null ) return - 1 ; try { return inputStream . read ( buffer , offset , count ) ; } catch ( IOException ex ) { throw new IOException ( ex ) ; } }
fills the buffer with more bytes . can be overridden to fill the bytes from a source other than the inputstream .
