我还有下节课

class Person {  private String name; }

class Student extends Person {  private int studyPlace;  private int studyYears; }

class Worker extends Person {  private String workPosition;  private int experienceYears; }

我想把所有这些类存储在一个集合中 List<Person> persons. 为了分类，我想用下一节课

class DurationComparator implements Comparator<Person> {

    @Override
    public int compare(Person o1, Person o2) {
        if (o1 == null && o2 == null) {
            return 0;
        }
        if (o1 == null) {
            return 1;
        }
        if (o2 == null) {
            return -1;
        }

        int p1 = 0;
        int p2 = 0;

        if (o1 instanceOf Student){
            p1 = ((Student) o1).getStudyYears();
        }

        if (o1 instanceOf Worker){
            p1 = ((Worker) o1).getExperienceYears();
        }

        if (o2 instanceOf Student){
            p2 = ((Student) o2).getStudyYears();
        }

        if (o2 instanceOf Worker){
            p2 = ((Worker) o2).getExperienceYears();
        }

        return p2 - p1;

    }
}

我知道lsp普林西比。将子类类型转换为基类型是一种好的做法吗？