Java Object-Oriented Programming Proficiency (Intermediate Level)

Topics covered

• access outer class variables from your anonymous inner class
• construct two parallel base classes and derived classes for each of those base classes
• create and define anonymous inner class objects
• create and use final classes and final methods
• create files using both the legacy java.io as well as the modern java.nio namespaces
• define and use static final member variables
• implement a derived class that can both extend a base class and implement an interface
• instantiate final arrays
• perform operations such as copying and creating directories using the Files class in the java.nio namespace
• perform operations such as copying files, checking for their existence, and deleting files using the Files class in the java.nio namespace
• perform various casting operations
• recognize how access works from one package into another
• recognize how polymorphism works in the presence of a multilevel inheritance hierarchy
• recognize how the instanceof operator works the same way with interfaces as with classes
• recognize how to extend abstract classes and the implications of doing so
• recognize how you can upcast multiple levels up and how downcasting is very dangerous
• recognize situations where multiple inheritance is not allowed
• recognize that a class can only be instantiated if it has implemented all abstract methods
• recognize that compile-time polymorphism does not include type demotions
• recognize the semantics of using default access modifiers inside the same package
• recognize the semantics of using default access modifiers outside the current package
• set up a class that implements some of the methods of an interface and then declares itself abstract
• set up two inheritance hierarchies and combine these into a set of objects that implement both set of interfaces
• use a combination of run-time and compile-time polymorphism
• use compile-time polymorphism, including type promotions
• use the instanceof operator to check that an object is an instance of every class in its inheritance hierarchy
• use the methods of the Path interface to normalize, parse, and resolve paths
• use the @Override annotation
• use the protected access modifier
• use the protected keyword across packages