问使用LimitFilter的比较器不起作用

EN

class Student {
    long studentId;
}

class StudentComparator implements Comparator<Student> {
    public int compare(Student o1, Student o2) {
       return o1.getStudentId() - o2.getStudentId();
    }
}

StudentComparator studentComparator = new StudentComparator();
EntryComparator comparator = new EntryComparator(studentComparator,EntryComparator.CMP_VALUE);
LimitFilter limitFilter = new LimitFilter(AlwaysFilter.INSTANCE, 5)
limitFilter.setComparator(comparator);
Set studentSet = null;
do {
   studentSet = studentCache.entrySet(limitFilter);
   .....
   // print the set
   .....
   limitFilter.nextPage();
} while (studentSet.size() > 0)

 public void setComparator(Comparator comparator) : Set the Comparator
 used to partition the values into pages.