TreeMap of Points - how do I set the comparator?

Question

I have a treemap containing Points and I know I have to set a comparator for the map.
I also know there is a comparator in class Point because there is an equals method.
How do I set the map comparator to use the Point comparator?

Answer 1

This is an example for the Point comparator
import java.awt.Point;
import java.util.Comparator;
import java.util.Iterator;
import java.util.TreeMap;
public class PointComparator implements Comparator {
    public int compare(Object o1, Object o2) {
        if (o1 == null && o2 == null) {
            return 0;
        } else if (o1 == null) {
            return -1;
        } else if (o2 == null) {
            return 1;
        Point pointFirstPoint = (Point) o1;
        Point pointSecondPoint = (Point) o2;
        int nComparationResult = 0;
        if (pointFirstPoint.x < pointSecondPoint.x
            || (pointFirstPoint.x == pointSecondPoint.x
                && pointFirstPoint.y < pointSecondPoint.y)) {
            nComparationResult = -1;
        } else if (pointFirstPoint.x > pointSecondPoint.x
                   || pointFirstPoint.y > pointSecondPoint.y) {
            nComparationResult = 1;
        return nComparationResult;
    public static void main(String args[]) {
        TreeMap map = new TreeMap(new PointComparator());
        map.put(new Point(0, 1), "some data");
        map.put(new Point(1, 1), "some data");
        map.put(new Point(-1, 3), "some data");
        map.put(new Point(2, 1), "some data");
        map.put(new Point(2, 7), "some data");
        map.put(new Point(2, 1), "some data");
        map.put(new Point(2, 9), "some data");
        map.put(new Point(2, 4), "some data");
        map.put(new Point(-1, -1), "some data");
        map.put(new Point(2, 3), "some data");
        Iterator it = map.keySet().iterator();
        while (it.hasNext()) {
            System.out.println(it.next());
}Foar any more questions please read the documentation for java.util.Comparator and java.lang.Comparable. There is more than enough information for what you need.