/** Class for a directory storing pairs of Student objects. */ public class StudentPairDirectory { protected PersonPairDirectory directory; public StudentPairDirectory() { directory = new PersonPairDirectory (); } public void insert(Student s, Student t) { directory.insert(s,t); } public Student findOther(Student s) { return (Student) directory.findOther(s); } public void remove(Student s, Student t) { directory.remove(s, t); } }