Difference between "implents Comparable" and "Comparable<T>" [duplicate]

Question

This question already has answers here:

What is a raw type and why shouldn't we use it? (15 answers)

Closed 8 years ago.

I've been having problems about this:

public class Student implements Comparable {
    private int id;
    private String name;



    public int compareTo(Student other) {
       return 1; // This is just an example value

    }
}

This program doesn't compile, as it says that it doesn't override the method "compareTo()" . Now why is that?

But if I use the following class header

public class Student implements Comparable<Student>{...}

it works fine. I need some explanation about this. By the way a lot of internet examples of the "Comparable" interface use the first class header, I mean without the Comparable.

Answer 1

Look at the source code of Comparable. With implements Comparable the method within student would be

public int compareTo(Object other) { ...

Using generics Comparable the method is like you wrote it.

By the way the compiler should have given you a helpful explanation.