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Baldwin explains the use of overloaded methods for the purpose of achieving compile-time polymorphism.

Revised: Thu Mar 31 11:22:34 CDT 2016

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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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  • Listing 1 . Definition of the class named A.
  • Listing 2 . Definition of the class named B.
  • Listing 3 . Definition of the driver class named Poly01.
  • Listing 4 . Complete program listing.


Previous modules introduced overloading and overriding methods. This module concentrates on the use of method overloading to achieve compile-time polymorphism .

Every class in Java is a direct or indirect subclass of the class named Object . Methods defined in the class named Object are inherited into all other classes. Inherited methods that are not declared final may be overridden to make their behavior more appropriate for objects instantiated from the new class.

Overloaded methods have the same name and different formal argument lists. They may or may not have the same return type.

Polymorphism manifests itself in Java in the form of multiple methods having the same name. This module concentrates on method overloading, sometimes referred to as compile-time polymorphism . Subsequent modules concentrate on method overriding, sometimes referred to as runtime polymorphism .

Overloaded methods may all be defined in the same class, or may be defined in different classes as long as those classes have a superclass-subclass relationship.

Discussion and sample code

Three concepts

In an earlier module, I explained that most books on OOP will tell you that in order to understand OOP, you must understand the following three concepts:

  • Encapsulation
  • Inheritance
  • Polymorphism

I agree with that assessment.

Encapsulation and inheritance

Previous modules in this series have explained Encapsulation and Inheritance. This module will tackle the somewhat more complex topic of Polymorphism.

Overloading and overriding methods

In the modules on inheritance, you learned a little about overloading and overriding methods (you will learn more about these concepts as you progress through these modules) . This module concentrates on the use of overloaded methods to achieve compile-time polymorphism.

Real-world scenarios

The sample programs that I used in the previous modules in this series dealt with two kinds of car radios:

  • Plain car radios
  • Car radios having built-in tape players

I couched those programs in a real-world scenario in an attempt to convince you that encapsulation and inheritance really do have a place in the real world.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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