Overview of Class Design

In some ways, section is the most important one of the entire course. This is because writing your own classes is the cornerstone of object-oriented programming. Java is an object-oriented programming language, and its entire model of programming requires that a programmer organize their code into classes.

Along with using methods, writing classes is also one of the foundations of good object-oriented programming and doing so will help organize your code to hide the details of your program. Like writing methods, writing and using classes gives your code a high-level structure because the details can be ignored unless the code for the classes is examined. It also adds to the reusability of your code - instead of writing the same code over and over again, you can just re-use the class. This leads to well-tested code that is easy to maintain.

In this module we will cover how to design and write your own classes. You have already been doing it an extent because your all your programs are classes. The difference is that now you will write classes that are re-usable so many applications and Applets can use them. Your new classes will help your Java programs perform their specific tasks, and so are often called helper classes .

The main points we will cover are how to:

• Organize your code into helper classes.
• Understand how to properly design a class so it accurately represents a real-world concept.
• Code your own classes.
• Understand and create instance variables.
• Understand and write constructors, access methods, and modifiers.
• Test your classes.
• Properly code classes that demonstrate encapsulation.