public void write(long fileOffset,byte[] buffer,int offset,int length) throws IOException {
  _file.seek(fileOffset);
  _file.write(buffer,offset,length);
}

public void write ( long fileOffset , byte [ ] buffer , int offset , int length ) throws IOException { _file . seek ( fileOffset ) ; _file . write ( buffer , offset , length ) ; }
writes a block from a given location .
