Java1600: objects and encapsulation

Pressing a radio button

Given the previous discussion, the numeric value 3, passed to the method when it is called, simulates the pressing of the third button on the front of the radio (or the fourth button if you elect to number your buttons 0, 1, 2, 3, 4, 5) .

Summary

This is the first in a miniseries of modules that describe and discuss the necessary and most significant (essential) aspects of OOP using Java.

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

• Encapsulation
• Inheritance
• Polymorphism

This module has concentrated on encapsulation. Encapsulation was used as a springboard for a discussion of objects.

A description of an object-oriented program was 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 was used to illustrate and discuss several aspects of software objects.

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

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

You saw 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).

You learned about Java references and reference variables. You learned a little about memory allocation for objects and variables in Java.

What's next?

The next module in the miniseries will introduce you to the Java class.

Continuing with the real-world example introduced in this module, the next module will provide a complete Java program that simulates the manufacture and use of a car radio.

Along the way, you will see examples of (or read about) class definitions, constructing objects, saving references to objects, setter methods, sending messages to objects, instance variables and methods, class variables, array objects, persistence, and objects performing actions.

Miscellaneous

This section contains a variety of miscellaneous information.

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