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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

find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
is it a question of log
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele 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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