private String listToString(List<String> stringList){
  StringBuilder concat=new StringBuilder();
  for (  String str : stringList) {
    concat.append(str);
    concat.append(System.getProperty("line.separator"));
  }
  return concat.toString();
}

private String listToString ( List < String > stringList ) { StringBuilder concat = new StringBuilder ( ) ; for ( String str : stringList ) { concat . append ( str ) ; concat . append ( System . getProperty ( "line.separator" ) ) ; } return concat . toString ( ) ; }
concatenates a list of strings to one line - separated string
