1  import java.util.*;
  2  
  3  public class TestTreeSetWithComparator {
  4    public static void main(String[] args) {
  5      // Create a tree set for geometric objects using a comparator
  6      Set<GeometricObject> set =
  7        new TreeSet<>(new GeometricObjectComparator());
  8      set.add(new Rectangle(4, 5));
  9      set.add(new Circle(40));
 10      set.add(new Circle(40));
 11      set.add(new Rectangle(4, 1));
 12  
 13      // Display geometric objects in the tree set
 14      System.out.println("A sorted set of geometric objects");
 15      for (GeometricObject element: set)
 16        System.out.println("area = " + element.getArea());
 17    }
 18  }