Using a Comparable Interface Java

Question

I need to implement a comparable interface into my code so I can compare multiple bits of information from my ArrayList e.g. height. Once I have this working I need to be able to call it in a switch statement. I think I've got the comparable interface bit working however it's showing up an error message when I try to call it in the switch statement. Does anyone have any ideas as to why this is/how I can fix it? I've just attached the relevant code but please say if I need to attach more.

Comparable Interface

public class Superhero implements Comparable<Superhero> {

public int compareTo(Superhero other) {
        return Integer.compare(this.height, other.height);
    }

Switch Statement

        case 5:

           System.out.println(sortMenu());
           int val = input.nextInt();
           switch (val) {
                //HEIGHT
                case 6:
                    System.out.println(Superhero.compareTo());
            }

            break;

EDIT

error message when I run the code added below:

Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - Erroneous tree type: <any>
at heros.java.Heros.main(Heros.java:54)
Java Result: 1

compiler error message:

method compareTo in class Superhero cannot be applied to given types;
require: Superhero
found: no arguments
reason: actual and formal argument lists differ in length

Answer 1

You have correctly identified that your problem is in this snippet of code:

case 5:
    System.out.println(sortMenu());
    int val = input.nextInt();
    switch (val) {
        //HEIGHT
        case 6:
             System.out.println(Superhero.compareTo());
    }
    break;

It's on this line:

System.out.println(Superhero.compareTo());

In this expression:

Superhero.compareTo()

Superhero looks like a variable here (variables should start with lowercase, so that is confusing) and you need to supply another Superhero object to it as follows:

Superhero anotherSuperhero = new Superhero();
System.out.println(Superhero.compareTo(anotherSuperhero));