The Problems with Inheritance

Reading

• Item 18: Favor Composition Over Inheritance
  Bloch, Joshua. Effective Java. 3rd ed., Addison-Wesley Professional, 2017.

Important concepts

• errors introduced by overriding methods
• composition
• forwarding
• wrapper class

Things to consider (exercises for yourself, not to turn in)

1. What does it mean for a class B to be a subtype of class A? What are some strategies you can imagine to determine whether every instance of B is really an A?
2. What happens when you override a method inherited from a superclass? Could you trace a series of method calls made be a subclass B which inherits from and overrides methods in superclass A?

Your response

What was particularly interesting, confusing, or exciting to you in this reading?