fork download
copy 
  1.     import java.util.*;
  2.  
  3.     /* Name of the class has to be "Main" only if the class is public. */
  4.     class Ideone {
  5.       static class A {}
  6.  
  7.       static class SubclassOfA extends A {}
  8.  
  9.       static class B {}
  10.  
  11.       static class SubclassOfB extends B {}
  12.  
  13.       public static void main(String[] args) throws java.lang.Exception {
  14.         try {
  15.           List<Map<A, B>> list = new ArrayList<>();
  16.  
  17.           // Would be compiler error, but use raw types to pretend it's OK.
  18.           List<Map<? extends A, ? extends B>> list2 = (List) list;
  19.  
  20.           Map<SubclassOfA, SubclassOfB> map = new HashMap<>();
  21.           list2.add(map);
  22.  
  23.           list.get(0).put(new A(), new B());
  24.  
  25.           SubclassOfA soa = map.keySet().iterator().next();
  26.         } catch (Exception e) {
  27.           e.printStackTrace(System.out);
  28.         }
  29.       }
  30.     }
  31.  
Success #stdin #stdout 0.05s 4386816KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
{Ideone$A@14ae5a5=Ideone$B@7f31245a}
java.lang.ClassCastException: Ideone$A cannot be cast to Ideone$SubclassOfA
	at Ideone.main(Main.java:26)
https://ideone.com/8Ve51K
language:
Java (HotSpot 12)
created:
6 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!