public String getYear(AbstractPost post) {
   for (String year : getYears()) {
     for (Keyword keyword : post.getKeywords()) {
       if (StringUtils.equalsIgnoreCase(year, keyword.getName())) {
         return year;
       }
     }
   }
   return "";
 }
  public List<String> getGrades(AbstractPost post) {
    List<String> grades = new ArrayList<String>();

    for (String grade : getGrades()) {
      for (Keyword keyword : post.getKeywords()) {
        if (StringUtils.equalsIgnoreCase(grade, keyword.getName())) {
          grades.add(grade);
        }
      }
    }
    return grades;
  }