// a nearest neighbor in the set to point p; null if the set is empty
public Point2D nearest(Point2D p) {
if (p == null) throw new NullPointerException("Point2D cannot be null!");
if (set.isEmpty()) return null;
double minDistance = Double.MAX_VALUE;
Point2D minPoint = null;
for (Point2D point : set) {
double distance = p.distanceSquaredTo(point);
if (distance < minDistance) {
minDistance = distance;
minPoint = point;
}
}
return minPoint;
}
// is the set empty?
public boolean isEmpty() {
return set.isEmpty();
}