So, I'm trying to implement a compareTo method to compare to the student and gather the time, but I'm unable to succeed in getting that method here is the code that I have
Many people are saying its a similar question, but it isn't because again, like i explained in the bottom it gives me an error because you CANNOT "compareTo(Student) is undefined for the type Student"
import java.util.ArrayList;
import java.util.List;
public class Student implements Student_Interface {
private String studentID;
private String name;
private List<Course> myEnrolledCourses;
private List<Course> myWaitlist;
private int courseCoins;
/**
* Constructor that populates the instance variables with parameters passed
* @param id StudentID
* @param name Name of the student
* @param coins Course Coins
*/
public Student(String id, String name, int coins) {
this.studentID = id;
this.name = name;
this.courseCoins = coins;
myEnrolledCourses = new ArrayList<>();
myWaitlist = new ArrayList<>();
}
/**
* Adds course c to the list of enrolled courses
* Also removes c from the waitlisted courses
* @param c Course to be enrolled in
*/
@Override
public void enrollCourse(Course c) {
myEnrolledCourses.add(c);
myWaitlist.remove(c);
}
/**
* Adds course c to the waitlist
* @param c course to be waitlisted
*/
@Override
public void waitlistCourse(Course c) {
myWaitlist.add(c);
}
/**
* Getter for name
* @return name - Name of the student
*/
@Override
public String getStudentName() {
return name;
}
/**
* Getter for Student ID
* @return studentID - Student ID
*/
@Override
public String getStudentID() {
return studentID;
}
/**
* Returns a list of all enrolled courses
* @return List of enrolled courses
*/
@Override
public List<Course> getmyEnrolledCourses() {
return myEnrolledCourses;
}
/**
* Returns a list of all waitlisted courses
* @return List of waitlisted courses
*/
@Override
public List<Course> getmyWaitlist() {
return myWaitlist;
}
/**
* Getter for course coins
* @return course coins
*/
@Override
public int getCoins() {
return courseCoins;
}
/**
* Deducts numCoins from coursecoins
* @param numCoins Number of coins to be deducted
*/
@Override
public void deductCoins(int numCoins) {
numCoins = numCoins - courseCoins;
}
/**
* Returns a string representation of the Student that includes
* the name and the studentID
* @return String representation of the student
*/
@Override
public String toString() {
return this.name + "("+this.studentID+")";
}
}
The code above is the Student class that follows this Register Class
public class Registration implements Comparable<Registration> {
private Student student;
private Course course;
private int coins;
private long timestamp;
public Registration(Student student, Course course, int coins) {
this.student = student;
this.course = course;
this.coins = coins;
setTimestamp();
}
/** Gets the students name **/
public Student getStudent() {
return student;
}
/** Gets the course name **/
public Course getCourse() {
return course;
}
/** Gets the coins **/
public int getCoins() {
return coins;
}
/**
* Compares this Student with another Student, by comparing their
* course coins/timestamps
* If the coins of this is less, returns a negative integer. If the
* coins of the Student received is less, returns a positive integer.
* If the number of coins is same, use the timestamp comparison to ensure FCFS.
* (You may want to check the implementation of System.nanoTime to ensure
* correctness)
* @param o Student to be compared with
* @return Result of the comparison
*/
@Override
public int compareTo(Registration o) {
//This is the method I need help with if(this.getStudent().equals(o.getStudent())){
if(this.getStudent().getCoins() == o.getStudent().getCoins()){
System.nanoTime(); // how would i use this??
}
if(this.getStudent().getCoins() < o.getStudent().getCoins()){
return -1;
}
if(this.getStudent().getCoins() > o.getStudent().getCoins()){
return 1;
}
}
return 1; //XXX-CHANGE-XXX
}
/**
* Sets the timestamp inside this registration to be the current time in nano seconds.
*/
public void setTimestamp() {
timestamp = System.nanoTime();
}
}
So As of right now, I have no idea how to implement the compareTo Method, I've googled and tried to use
this.getStudent().compareTo(o.getStudent());
I get an Error and it states: method compareTo(Student) is undefined for the type Student I'm not sure in how to go about this! Please help me understand! Thanks in advance.
