Sorting Objects By A Number Of Fields

I am trying to find a concise way to write the sort methods for my class. I am supposed to make a program that can sort objects by a number of fields: year, rank, artist and title.

I used an idea from this thread : java - Sorting a collection of objects - Stack Overflow

And I am trying to use the custom comparator for my sort methods. However for some reason, the sortingBy variable fails to recognize any of the enum types.

Whenever I try to set the sortingBy variable equal to one of them, for example:

Java Code:

private Order sortingBy = Year; mh_sh_highlight_all('java');

I get a "Year cannot be resolved to a variable" error.

What I want to be able to do is make it so every time a specific method is called, say, for example sortTitle(), sortingBy will change to Title, then the SongComparator will sort using the case Title.

Is it possible to do this? I can't figure out how to modify SongComparator's object variables that way.

Java Code:

import java.util.Comparator;
public class SongComparator implements Comparator<Song> {
public enum Order {Year, Rank, Artist, Title}
public Order sortingBy;

[Code] .....