HashSet w porównywaniu obiektów?

Area a = DAO.AreaDAO.getAreaById(Integer.valueOf(index));    
       Set<Question> questions = new HashSet<Question>(0);
       questions = a.getQuestions();       
       boolean x = questions.contains(question);

  public int hashCode() {
        return (int)this.id;
    }
  
   public boolean equals(Question other) {
        return (int)this.id == (int)other.id;
    }

@Override
public int hashCode(){
    StringBuffer buffer = new StringBuffer();
    buffer.append(this.id);
    buffer.append(this.version);
    buffer.append(this.description);
    buffer.append(this.active);
    return buffer.toString().hashCode();
}


@Override
public boolean equals(Object object){
    if (object == null) return false;
    if (object == this) return true;
    if (this.getClass() != object.getClass())return false;
    Question questions = (Question)object;
    if(this.hashCode()== questions.hashCode())return true;
   return false;
}  

       Set<Question> questions = new HashSet<Question>(0);
       questions = a.getQuestions();      

       Set<Question> questions = a.getQuestions();