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Figure 2 . Text output for overridden ToString method and class B.

ToString in class B

Do you recognize this?

You should recognize this as the text that was encapsulated in the String object returned by the overridden version of the ToString method defined in the class named B . (See Listing 2 .)

Overridden version of ToString was executed

This verifies that even though the reference to the object of the class B was stored in a reference variable of type Object , the overridden version of the ToString method in the class named B was executed (instead of the default version defined in the class named Object) . This is runtime polymorphic behavior , as described in a previous module.

Once again, what is the rule?

The selection of a method for execution is based on the actual type of object whose reference is stored in a reference variable, and not on the type of the reference variable on which the method is called.

An object of the class C

Finally, the code in Listing 6

  • Instantiates a new object of the class C
  • Stores the object's reference in a reference variable of type Object
  • Calls the ToString method on the reference and saves the returned string
  • Displays the returned string on the computer screen

Listing 6 . An object of the class C.

Object varC = new C(); String v3 = varC.ToString();Console.WriteLine(v3); //Pause until user presses any key.Console.ReadKey();}//end Main }//end class Polymorph04

What will the output look like?

By now, you should know what to expect in the way of text appearing on the computer screen. The code in Listing 6 causes the text shown in Figure 3 to be displayed.

Figure 3 . Text output for overridden ToString method and class C.

ToString in class C

Overridden version of ToString was called

This confirms what you should already have known by now. In particular, even though the reference to the object of the class C was stored in a reference variable of type Object , the overridden version of the ToString method defined in the class named C was executed. Again, this is runtime polymorphic behavior based on class inheritance and method overriding.

No downcasting was required

It is also very important to note that no downcasting was required in order to call the ToString method in any of the cases shown above.

Because a default version of the ToString method is defined in the Object class, that method can be called without a requirement for downcasting on a reference to any object stored in a variable oftype Object . This holds true for any of the methods defined in the class named Object .

A generic array object

Therefore, if we create an array object designed to store references of type Object , we can store (potentially mixed) references to any type of object in that array. We can later call any of the methods definedin the Object class on any of the references stored in the array.

The result will be the execution of the overridden version of the method as defined in the class from which the object was instantiated, or the versioninherited into that class if the method is not overridden in that class. Current jargon would say that the behavior of the method is appropriate for the type of object on which it is called.

Questions & Answers

Application of nanotechnology in medicine
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.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
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
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
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
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
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