Question

Currently I have a comparator class in the same file as one of my classes.

public class Tree {

    public static Comparator<Tree> TreeSize = new Comparator<Tree>() {
        public int compare(Tree t1, Tree t2)
        {
            etc...
        }
    }

}

Should the Comparator class be in its own file?

Answer 1

If you happen to have just one comparator, why not just impose a natural ordering by having the class implement Comparable? Then you can not only keep it at the class level, but you don’t need the second class at all.