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Baldwin concentrates on a discussion of the Java class. He shows you how to write a very simple program that simulates the manufacture and use of the car radio introduced in an earlier module.

Revised: Wed Mar 30 18:00:37 CDT 2016

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Table of contents

Preface

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

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This module will concentrate primarily on a discussion of the Java class .

A simple Java program will be discussed to illustrate the definition and use of two different classes. Taken in combination, these two classes simulate the manufacture and the use of the car radio object discussed in an earlier module.

You will see how to write code to create a new Radio object by applying the new operator to the class named Radio . You will also see how to save that object's reference in a reference variable of type Radio .

You will see how to write code that is used to simulate the association of a radio button with a particular radio station.

You will see how to write code that is used to simulate the pressing of a radio button to play the radio station associated with that button.

You will see the definition of a class named Radio01 . This class consists simply of the main method. The main method of a Java application is executed by the Java Virtual Machine when the application is run. Thus, it is the driver for the entire application.

You will see the definition of a class named Radio . This class includes one instance variable and two instance methods.

(The instance variable is a reference variable that refers to a special kind of object that I refer to as an array object. I will provide a very brief discussion on array objects in this module. I will have more to say about array objects in a subsequent module.)

I will also provide a short discussion of class variables, which are not used in this program. I will explain that the use of class variables can often lead to undesirable side effects.

Finally, I will provide a very brief discussion of the syntax of a simple class definition in Java.

Discussion and sample code

What is a class?

I explained in an earlier module that a class is a plan from which many objects can be created. I likened the class definition to the plans from which millions of nearly identical car radios can be produced.

Questions & Answers

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At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
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Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
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