void addClassList(String classListFilename){
  if (classListFilename.length() > 0) {
    setOption("classlist",classListFilename);
    loadClassNames(classListFilename);
  }
 else {
    throw new IllegalArgumentException("class list name may not be empty string");
  }
}

void addClassList ( String classListFilename ) { if ( classListFilename . length ( ) > 0 ) { setOption ( "classlist" , classListFilename ) ; loadClassNames ( classListFilename ) ; } else { throw new IllegalArgumentException ( "class list name may not be empty string" ) ; } }
adds a class list filename to this set of options .
