// Class to represent a rectangle
public class Rectangle implements Shape {
   private double length;
   private double width;
   
   public Rectangle(double length, double width) {
      this.length = length;
      this.width = width;
   }
   
   // returns the area of this rectangle
   public double area() {
      return length * width;
   }
   
   // compares this rectangle to other by area
   // pre: other != null
   public int compareTo(Shape other) {
      if (this.area() < other.area()) {
         return -1;
      } else if (this.area() > other.area()) {
         return 1;
      } else {
         return 0;
      }
   }
   
   public String toString() {
      return "rectangle of area " + String.format("%.3f", area());
   }   
}