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interface X{ public void intfcMethodX();}//end X

Class A extends Base and implements X

The next fragment shows the definition of a class named A that extends Base and implements X .

class A extends Base implements X{ public void inherMethod(){System.out.print( " A-inherMethod ");}//end inherMethod()public void intfcMethodX(){ System.out.print("A-intfcMethodX "); }//end intfcMethodX()}//end class A

Defining interface method

Because the class named A implements the interface named X , it must provide a concrete definition of all the methods declared in X .

In this case, there is only one such method. That method is named intfcMethodX . A concrete definition for the method is provided in the class named A .

Class B also extends Base and implements X

The next fragment shows the definition of another class (named B ), which also extends Base and implements X .

class B extends Base implements X{ public void inherMethod(){System.out.print( " B-inherMethod ");}//end inherMethod()public void intfcMethodX(){ System.out.print("B-intfcMethodX "); }//end intfcMethodX()}//end class B

Defining the interface method

Because this class also implements X , it must also provide a concrete definition of the method named intfcMethodX .

Different behavior for interface method

However (and this is extremely important) , there is no requirement for this definition of the method to match the definition in the class named A , or to match the definition in any other class that implements X .

Only the method signature for the method named intfcMethodX is necessarily common among all the classes that implement the interface.

The definition of the method named intfcMethodX in the class named A is different from the definition of the method having the same name in the class named B .

The interesting behavior

The interesting behavior of this program is illustrated by the code in the following fragment.

void doIt(){ X myVar1 = new A();myVar1.intfcMethodX();X myVar2 = new B(); myVar2.intfcMethodX();System.out.println(""); }//end doIt()

Store object's references as interface type X

The code in the above fragment causes one object to be instantiated from the class named A , and another object to be instantiated from the class named B .

The two object's references are stored in two different reference variables, each declared to be of the type of the interface X .

Call the interface method on each reference

A method named intfcMethodX is called on each of the reference variables. Despite the fact that both object's references are storedas type X , the system selects and calls the appropriate method, (as defined by the class from which each object was instantiated) , on each of the objects. This causes the following text to appear on the screen:

A-intfcMethodX B-intfcMethodX

No subclass-superclass relationship exists

Thus, the use of an interface makes it possible to call methods having the same signatures on objects instantiated from different classes, without anyrequirement for a subclass-superclass relationship to exist among the classes involved.

Questions & Answers

what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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.
Bharti
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
Daniel
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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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