Comparator for TreeMap Integer[], Double

Question

Hi all,
I'm trying to write a compartor for a TreeMap<Integer[], Double>. The Integer[] has always two entries and [x,y] should be equal to [y,x].
This is my code:
TreeMap<Integer[], Double> t = new TreeMap<Integer[], Double>(new Comparator(){
            public int compare(Object o1, Object o2) {
                Integer[] i1 = (Integer[]) o1;
                Integer[] i2 = (Integer[]) o2;
                if (i1[0].equals(i2[0]) && i1[1].equals(i2[1]))
                    return 0;
                if (!i1[0].equals(i2[0]))
                    return i1[0].compareTo(i2[0]);
                return i1[1].compareTo(i2[1]);
        });However, after inserting two elements like
t.put(new Integer[]{1,2}, 0.1);
t.put(new Integer[]{2,1}, 0.2);, the TreeMap contains these two elements instead of just one.
Is there an error in my Comparator?
Regards,
Andreas

Answer 1

the two elements are inside your map because their keys new Integer[]{1,2} and new Integer[]{2,1} are different, so they represent different values.
To make this simpler, one possibility is to create a wrapper class for these two integers, and override equals()