Java1600: objects and encapsulation

Revised: Wed Mar 30 17:09:41 CDT 2016

This page is included in the following Books:

• ITSE 2321 - Object-Oriented Programming (Java)
• Object-Oriented Programming (OOP) with Java

Table of contents

• Preface
  • The essence of OOP
  • Viewing tip
    • Listings
• Preview
• Discussion and sample code
• Summary
• What's next?
• Miscellaneous

Preface

This module is the first in a series of modules designed to teach you about the essence of Object-Oriented Programming (OOP) using Java.

The essence of OOP

My dictionary provides several definitions for the word essence. Among those definitions are the following:

• The property necessary to the nature of a thing
• The most significant property of a thing

Thus, this miniseries will describe and discuss the necessary and most significant aspects of OOP using Java. In other words, I will discuss theessence of OOP using Java. For the first few modules, I will provide that information in a high-level format, devoid of any requirement to understand detailed Java syntax. In those cases where an understanding of Java syntax is required, I will provide the necessary syntax information in the form of supplementary notes.

Therefore, if you have a general understanding of computer programming, you should be able to read and understand the modules in this miniseries, even if you don't have a strong background in the Java programming language.

Viewing tip

I recommend that you open another copy of this document in a separate browser window and use the following links to easily find and view the listings while you are reading about them.

Listings

• Listing 1 . Instantiating a new Radio object.
• Listing 2 . Calling the playStation method.

Preview

In order to understand OOP, you need to understand the following three concepts:

• Encapsulation
• Inheritance
• Polymorphism

This module will concentrate on encapsulation. Encapsulation will be used as a springboard for a discussion of objects.

A description of an object-oriented program will be provided, along with a description of an object, and how it relates to encapsulation.

In order to relate object-oriented programming to the real world, a car radio will be used to illustrate and discuss several aspects of software objects. For example, you will learn that car radios, as well as software objects, have the ability to store data, along with the ability to modify or manipulate that data.

You will learn that car radios, as well as software objects, have the ability to accept messages and to perform an action, modify their state, return a value, or some combination of the above.

You will learn some of the jargon used in OOP, including persistence, state, messages, methods, and behaviors.

You will learn where objects come from, and you will learn that a class is a set of plans that can be used to construct objects. You will learn that a Java object is an instance of a class .

You will see a little bit of Java code, used to create an object, and then to send a message to that object (invoke a method on the object).