CompareTo Method: Return Type: GREATER, EQUAL, LESS

Question

I'm receiving these 4 errors: character expected errors character expected errors I'm doing a LinkedList java project that requires the implementation of the CompareTo method. I am rusty on Java and would like some help regarding what I am doing wrong regarding this implementaion. Should I use integers instead of enums? Should I use switch/case/break instead of if/else?

Here's my Java class file for class ItemType

import java.util.Objects;

public class ItemType {
    private int value;

    public ItemType() {
        // Constructor body can be empty if there's no initialization code needed
    }

    public enum compareTo(ItemType item) {
        if (this.getValue() < item.getValue()) {
            return LESS;
        } else if (this.getValue() > item.getValue()) {
            return GREATER;
        } else {
            return EQUAL;
        }
    }

    public int getValue() {
        return value;
    }

    public void initialize(int num) {
        value = num;
    }

    // Assuming Comparison is an enum, you would also need to define it in Java
    //public enum Comparison {
        //LESS,
        //GREATER,
        //EQUAL
    //}
}

Here's an example of the SortedLinkedList.java class using the ItemType class method compareTo()

while (location.next != null && brake == 0) {
      switch (item_.compareTo(location.item)) {
            case ItemType.GREATER:
                preLoc = location;
                location = location.next;
                break;
            case ItemType.EQUAL:
                System.out.println("\nError: Duplication\n");
                return;
            case ItemType.LESS:
                brake = 1;
                break;
            }
}

Answer 1

You actually do not need your enum. Try to implement Comparable interface. You can take a look how to do it here.

Then rework your switch case to work with integer like:

    switch (item_.compareTo(location.item)) {
        case 1:
            preLoc = location;
            location = location.next;
            break;
        case 0:
            System.out.println("\nError: Duplication\n");
            return;
        case -1:
            brake = 1;
            break;
    }

Happy coding!

UPD

Example how to implement (be aware it is not final version and you can provide your own implementation):

    public class ItemType implements Comparable<ItemType> {
    private int value;

    public ItemType() {
        // Constructor body can be empty if there's no initialization code needed
    }

    @Override
    public int compareTo(ItemType o) {
        if (this.value > o.value) {
            return 1;
        }

        if (this.value == o.value) {
            return 0;
        }

        return -1;
    }
}