public void writeMapping(Writer w) throws IOException {
  w.write("# Mapping file, generated " + (new Date()) + "\n");
  for (  Integer key : id2name.keySet()) {
    w.write(key + "\t" + id2name.get(key)+ "\n");
  }
}

public void writeMapping ( Writer w ) throws IOException { w . write ( "# Mapping file, generated " + ( new Date ( ) ) + "\n" ) ; for ( Integer key : id2name . keySet ( ) ) { w . write ( key + "\t" + id2name . get ( key ) + "\n" ) ; } }
write the new mapping
