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Call the test method differently

However, the call of the method named test in the object instantiated from the class named B is somewhat different. The difference is identified by the code in the followingfragment.

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

Calling test method on Base-type reference

In Question 9 , and in the above code fragment as well, the method named test was called on each of the objects using a reference stored in a reference variable of type Base .

Calling the overridden version of test method

This might be thought of as calling the overridden version of the method, through polymorphism, without regard for anything having to do with theinterfaces.

Calling test method on interface-type reference

Then the code shown above calls the same method named test on one of the same objects using a reference variable of the interface type X .

Only one test method in each object

Keep in mind that each object defines only one method named test . This single method serves the dual purpose of overriding the method having thesame signature from the superclass, and implementing a method with the same signature declared in each of the interfaces.

Implementing the interface method

Perhaps when the same method is called using a reference variable of the interface type, it might be thought of as implementing the interface methodrather than overriding the method defined in the superclass. You can be the judge of that.

The same method is called regardless of reference type

In any event, in this program, the same method is called whether it is called using a reference variable of the superclass type, or using a reference variable of the interface type.

Illustrates the behavior of signature collisions

The purpose of this and Question 9 is not necessarily to illustrate a useful inheritance and implementation construct. Rather, these twoquestions are intended to illustrate the behavior of Java for the case of duplicated superclass and interface method signatures.

Back to Question 10

Answer 9

C. Base A B

Explanation 9

A question regarding signature collisions

The question often arises in my classroom as to what will happen if a class inherits a method with a given signature and also implements one or moreinterfaces that declare a method with an identical signature.

The answer

The answer is that nothing bad happens, as long as the class provides a concrete definition for a method having that signature.

Only one method definition is allowed

Of course, only one definition can be provided for any given method signature, so that definition must satisfy the needs of overriding the inheritedmethod as well as the needs of implementing the interfaces.

An example of signature collisions

The following fragment defines a class named Base that defines a method named test . The code also defines two interfaces named X and Y , each of which declares a method named test with an identical signature.

Questions & Answers

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 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
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
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
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
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.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
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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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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