Difference between <? super T> and <? extends T> in Java [duplicate]

Answer 1

I'd like to visualize the difference. Suppose we have:

class A { }
class B extends A { }
class C extends B { }

List - reading and assigning:

|-------------------------|-------------------|---------------------------------|
|         wildcard        |        get        |              assign             |
|-------------------------|-------------------|---------------------------------|
|    List    |    A    B    C    |                       List   |
|-------------------------|-------------------|---------------------------------|
|    List    |    A    B         |             List   List   |
|-------------------------|-------------------|---------------------------------|
|    List    |    A              |   List   List   List   |
|-------------------------|-------------------|---------------------------------|

List - writing and assigning:

|-------------------------|-------------------|-------------------------------------------|
|         wildcard        |        add        |                   assign                  |
|-------------------------|-------------------|-------------------------------------------|
|     List     |              C    |  List