import java.util.*; public class TestTreeSetWithComparator { public static void main(String[] args) { // Create a tree set for geometric objects using a comparator Set<GeometricObject> set = new TreeSet<>(new GeometricObjectComparator()); set.add(new Rectangle(4, 5)); set.add(new Circle(40)); set.add(new Circle(40)); set.add(new Rectangle(4, 1)); // Display geometric objects in the tree set System.out.println("A sorted set of geometric objects"); for (GeometricObject element: set) System.out.println("area = " + element.getArea()); } }