public static String join(String separator,double... elements){
  if (elements == null || elements.length == 0) {
    return "";
  }
  List<Number> list=new ArrayList<Number>(elements.length);
  for (  Double elem : elements) {
    list.add(elem);
  }
  return join(separator,list);
}

public static String join ( String separator , double ... elements ) { if ( elements == null || elements . length == 0 ) { return "" ; } List < Number > list = new ArrayList < Number > ( elements . length ) ; for ( Double elem : elements ) { list . add ( elem ) ; } return join ( separator , list ) ; }
returns a string with all double values concatenated by a specified separator .
