import java.util.List;
import java.util.ArrayList;

/** Demo the use of generics.
    @author Jed Yang, 2018-04-06
*/
public class GenericsDemo
{
   public static void main(String[] args)
   {
      List<Shape> list1 = new ArrayList<Shape>();

      list1.add(new Rectangle());
      list1.add(new Circle());
      for (Shape shape : list1)
      {
         System.out.println(shape);
         System.out.println("area = " + shape.getArea());
         System.out.println("perimeter = " + shape.getPerimeter());
         System.out.println();
      }

//      List<Shape> list2 = new ArrayList<Circle>();
//      list2.add(new Rectangle());
      List<Circle> list3 = new ArrayList<Circle>();
//      List<Circle> list4 = new ArrayList<Shape>();

//*
      List<List<Shape>> list5 = new List<List<Shape>>();
      List<List<Shape>> list6 = new List<ArrayList<Shape>>();
      List<List<Shape>> list7 = new ArrayList<List<Shape>>();
      List<List<Shape>> list8 = new ArrayList<ArrayList<Shape>>();
//*/
   }
}