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What does this allow you to do?

When a reference to an object is held by a reference variable whose type matches an interface implemented by the class from which the object wasinstantiated, that reference can be used to call any method declared in or inherited into that interface.

(That reference cannot be used to call methods not declared in or not inherited into that interface.)

In this simple case ...

The method named intfcMethod is declared in the interface named X and implemented in the class named A .

Therefore, the method named intfcMethod can be called on an object instantiated from the class named A when the reference to the object is held in a reference variable of the interface type.

(The method could also be called if the reference is being held in a reference variable of declared type A .)

The call to the method named intfcMethod causes the text A-intfcMethod to appear on the screen.

Back to Question 4

Answer 3

C. Base A-intfcMethod

Explanation 3

What is runtime polymorphic behavior?

One way to describe runtime polymorphic behavior is:

The runtime system selects among two or more methods having the same signature, not on the basis of the type of the reference variable in which an object'sreference is stored, but rather on the basis of the class from which the object was originally instantiated.

Illustrates simple class and interface inheritance

The program defines a class named Base , and a class named A , which extends Base , and implements the interface named X , as shown in the following fragment.

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

Define an interface method

The interface named X declares a method named intfcMethod . A concrete definition of that method is defined in the class named A .

A new object of type Base

The code in the following fragment instantiates a new object of the class Base and calls its inherMethod . This causes the word Base to appear on the output screen. There is nothing special about this. This is a simple example of the use of an object's reference to call one of itsinstance methods.

void doIt(){ Base myVar1 = new Base();myVar1.inherMethod();

A new object of type A

The following fragment instantiates a new object of the class A and calls its intfcMethod . This causes the text A-intfcMethod to appear on the output screen. There is also nothing special about this. This is also a simple example of the use of anobject's reference to call one of its instance methods.

A myVar2 = new A(); myVar2.intfcMethod();System.out.println(""); }//end doIt()

Not polymorphic behavior

The fact that the class named A implements the interface named X does not indicate polymorphic behavior in this case. Rather, this program is an example of simple class and interface inheritance.

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar 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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