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An inherited virtual method can be overridden by every class that inherits it, resulting in potentially many differentoverridden versions of a given method in a class hierarchy.

Listing 3 . Definition of class C.

class C : B { public override String ToString() {return "ToString in class C"; }//end overridden ToString()}//end class B

Behavior of overridden version

The behavior of this overridden version of the method is similar to, but different from the overridden version in the class B.

In this case, the method returns a reference to a String object that can be used to confirm that this overridden version of the methodhas been executed.

The driver class

Listing 4 shows the beginning of the driver class named Polymorph04 .

Listing 4 . Beginning of the driver class.

public class Polymorph04 { public static void Main() {Object varA = new A(); String v1 = varA.ToString();Console.WriteLine(v1);

A new object of the class A

The Main method of the driver class begins by instantiating a new object of the class A, and saving the object's reference in a reference variable of type Object , named varA .

It is very important to note that even though the object was instantiated from the class named A , the reference was saved as type Object , not type A.

Call ToString method on the reference

Then the code in Listing 4 calls the ToString method on the reference variable named varA , saving the returned reference to the String object in a reference variable of type String named v1 .

Display the returned String

Finally, that reference is passed to the WriteLine method, causing the String returned by the ToString method to be displayed on the computer screen. This causes the text shown in Figure 1 to be displayed.

Figure 1 . Text output for ToString method and class A.


Default ToString behavior

What you are seeing here is the String produced by the default version of the ToString method, as defined by the class named Object . The default implementation of the ToString method returns the fully qualified name of the type of the object. In this case, the object was instantiated from the class named A (so the type of the object is A ) .

Class A does not override ToString

Recall that our new class named A does not override the ToString method. Therefore, when the ToString method is called on a reference to an object of the class A, the default version of the method is executed, producing the output shown in Figure 1 .

A new object of the class B

Now consider the code shown in Listing 5 , which instantiates a new object of the class named B , and stores the object's reference in a reference variable of type Object .

Listing 5 . A new object of the class B.

Object varB = new B(); String v2 = varB.ToString();Console.WriteLine(v2);

Call ToString and display the result

The code in Listing 5 calls the ToString method on the reference of type Object , saving the returned reference in the reference variable named v2 . (Recall that the ToString method is overridden in the class named B .)

As before, the reference is passed to the WriteLine method, which causes the text shown in Figure 2 to be displayed on the computer screen.

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.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
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 did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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