Java & OO Intermediate - Part 2

Inheritance

• Given a class hierarchy, identify parents and children
• Use the correct Java syntax for extending a class.
• Write expressions that upcast or downcast a reference (no tricks, no arrays).

Object

• Know that java.lang.Object is the ultimate ancestor.
• Identify methods inherited from the Object class.
• Write correct implementation of the toString() method.

Overriding

• Explain the overriding mechanism and late binding
• From given code including a late binding call, predict the method that will be called.
• Identify correct overriding syntax, distinguish between the overriding and overloading mechanism.

Abstract

• Write code that declares abstract classes and methods
• Understand that an abstract class cannot be instantiated
• Know that once a class contains an abstract method, it must be marked as abstract.

Interfaces

• Write code that declares an interface and its containing methods.
• Make a class implement an interface correctly.
• Explain the particular nature of attributes declared in interfaces.
• Identify differences between implementing an interface and extending a class.
• Know that all methods of an interface are public.

instanceof

• Write code that uses the instanceof operator for run-time type identification.
• Identify correct operands of the instanceof operator

Access modifiers

• From a given situation, predict if a method can access a class attributes/methods, whatever of the 4 access modifiers are applied on these attributes/methods.
• Select the appropriate access modifier to enable a class to access or not access an attribute/method.

Overloading

• Implement constructor an method overloading correctly.
• Know that two methods cannot differ only on the return type.

Annotation

• Use the @Override annotation