1Z0-808 (Java 8 OCA) : Java Inheritance and Polymorphism

In this course, I answer 20 random questions from Enthuware’s Inheritance category and use diagrams and code where needed. The diagrams in particular are extremely helpful when explaining Inheritance-related concepts. For example, a UML diagram helps greatly with explaining why a reference of type Car cannot refer to an object of type Vehicle. The other type of diagram I use frequently is the in-memory representation of references referring to objects. Separating these two concepts (references and objects) is critical to answering many MCQ-style questions.

While the course is ideal for those preparing for the 1Z0-808 exam, the topics discussed will benefit anyone trying to understand Inheritance at a deeper level. For example, the following topics are all covered:

• method overriding
  • polymorphism
  • covariant returns
  • where the parent method throws exceptions
• method overloading
• upcasting and downcasting
• shadowing – both methods and data
• the reference type determines the methods accessible
• the default modifiers applied to interface data
• the types of methods allowed in interfaces
• why an abstract class can implement an interface without implementing any of the interfaces’ methods
• ClassCastExceptions