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Baldwin shows you how to use method overriding to cause the behavior of a method inherited into a subclass to be appropriate for an object instantiated from the subclass.

Revised: Thu Mar 31 10:37:32 CDT 2016

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Table of contents

Preface

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

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This module builds on the previous module . It is recommended that you study that module before embarking on this module.

The program discussed in this module extends a Radio class to produce a new class that simulates an upgraded car radio containing a tape player.

Method overriding is used to modify the behavior of a method of the Radio class named playStation , to cause that method to behave appropriately when a tape has been inserted into the tape player.

Discussion and sample code

Inheriting methods and variables

When you define a class that extends another class, an object instantiated from your new class will contain all of the methods and all of the variables defined in your new class. The object will also contain all of the methods and all of the variables defined in all of the superclasses of your new class.

The behavior of the methods

The behavior of the methods defined in a superclass and inherited into your new class may, or may not, be appropriate for an object instantiated from your new class. If those methods are appropriate, you can simply leave them alone.

Overriding to change behavior

If the behavior of one or more methods defined in a superclass and inherited into your new class is not appropriate for an object of your new class, you can change that behavior by overriding the method in your new class.

How do you override a method?

To override a method in your new class, simply reproduce the name, argument list, and return type of the original method in a new method definition in your new class. Then provide a body for the new method. Write code in that body to cause the behavior of the overridden method to be appropriate for an object of your new class.

Here is a more precise description of method overriding taken from the excellent book entitled The Complete Java 2 Certification Study Guide , by Roberts, Heller, and Ernest:

"A valid override has identical argument types and order, identical return type, and is not less accessible than the original method. The overriding method must not throw any checked exceptions that were not declared for the original method."

Questions & Answers

what is microbiologist
Muhammad Reply
what is errata
Muhammad
is the branch of biology that deals with the study of microorganisms.
Ntefuni Reply
What is microbiology
Mercy Reply
studies of microbes
Louisiaste
when we takee the specimen which lumbar,spin,
Ziyad Reply
How bacteria create energy to survive?
Muhamad Reply
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Muhamad
they make spores
Louisiaste
what is sporadic nd endemic, epidemic
Aminu Reply
the significance of food webs for disease transmission
Abreham
food webs brings about an infection as an individual depends on number of diseased foods or carriers dully.
Mark
explain assimilatory nitrate reduction
Esinniobiwa Reply
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
Elkana
Examples of thermophilic organisms
Shu Reply
Give Examples of thermophilic organisms
Shu
advantages of normal Flora to the host
Micheal Reply
Prevent foreign microbes to the host
Abubakar
they provide healthier benefits to their hosts
ayesha
They are friends to host only when Host immune system is strong and become enemies when the host immune system is weakened . very bad relationship!
Mark
what is cell
faisal Reply
cell is the smallest unit of life
Fauziya
cell is the smallest unit of life
Akanni
ok
Innocent
cell is the structural and functional unit of life
Hasan
is the fundamental units of Life
Musa
what are emergency diseases
Micheal Reply
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life
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Heyy Lubega hussein where are u from?
_Adnan
en français
Adama
which site have a normal flora
ESTHER Reply
Many sites of the body have it Skin Nasal cavity Oral cavity Gastro intestinal tract
Safaa
skin
Asiina
skin,Oral,Nasal,GIt
Sadik
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Sadik
How can Commensal Bacteria change into pathogen?
Sadik
all
Tesfaye
by fussion
Asiina
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Micheal
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Micheal
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Shelly Reply
part of a tissue or an organ being wounded or bruised.
Wilfred
what term is used to name and classify microorganisms?
Micheal Reply
Binomial nomenclature
adeolu
what's microbiome?
john Reply
Microbiology is the scientific study of microorganisms
Ibra
the microorganisms in a particular environment (including the body or a part of the body).
Ibra
describe the bacterial cell
Akello
The biggest populations of microbes reside in the gut.other popular habitats include the skin genitals.The microbial cells and their genetic material ,the microbiome ,live with human from birth .
Zahreen
can agriculture be integrated into biology
David
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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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