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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

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
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
How can I make nanorobot?
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
how can I make nanorobot?
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
While the American heart association suggests that meditation might be used in conjunction with more traditional treatments as a way to manage hypertension
Beverly Reply
in a comparison of the stages of meiosis to the stage of mitosis, which stages are unique to meiosis and which stages have the same event in botg meiosis and mitosis
Leah Reply
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