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Lesson 1

Introduction to Classes, Interfaces, and Objects in Java

One of Java's strengths is its excellent support for object-oriented programming. This support is provided through classes and interfaces, which are the building blocks of all Java programs.
The ability to effectively use classes and interfaces is an essential Java programming skill. The certification exam recognizes the importance of class and interface fundamentals and contains a number of questions that test your knowledge of them. This module reviews these topics and identifies any important points that you should know in preparation for the exam.


Module objectives

This module will review your knowledge of Java classes and interfaces, provide examples of their use, and help you to satisfy the following exam objectives:
  1. Declare classes and inner classes, making appropriate use of all permitted modifiers (such as public, final, static, abstract, and so on).
  2. Identify correctly constructed class declarations (of all forms, including inner classes), interface declarations, and implementations.
  3. State the benefits of encapsulation in object-oriented design, and write code that implements tightly encapsulated classes and the relationships "is a" and "has a."
  4. Write code to construct instances of any concrete class, including normal top-level classes, inner classes, static inner classes, and anonymous inner classes.
  5. For a given class, determine if a default constructor will be created, and if so, state the prototype of that constructor.