private void addAnswer(String riddle,String answer){
  Collection<String> answers=riddles.get(riddle);
  if (answers == null) {
    answers=new LinkedList<String>();
    riddles.put(riddle,answers);
  }
  answers.add(answer);
}

private void addAnswer ( String riddle , String answer ) { Collection < String > answers = riddles . get ( riddle ) ; if ( answers == null ) { answers = new LinkedList < String > ( ) ; riddles . put ( riddle , answers ) ; } answers . add ( answer ) ; }
add an answer to a riddle . add the riddle too if it did not exist before .
