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In this case, the only subclass-superclass relationship between the classes named A and B was that they were both subclasses of the same superclass. Even that relationship was established forconvenience, and was not a requirement.

Different behavior of interface methods

The methods having the same signature, (declared in the common interface, and defined in the classes) , need not have any similarity in terms of behavior.

A new interface relationship

The fact that both classes implemented the interface named X created a new relationship among the classes, which is not based onclass inheritance.

Back to Question 5

Answer 4

C. Base A-intfcMethod

Explanation 4

Illustrates the use of an interface as a type

The program defines a class named Base , and a class named A , which extends Base , and implements an interface named X , as shown below.

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

Implementing interfaces

A class may implement none, one, or more interfaces.

The cardinal rule on interfaces

If a class implements one or more interfaces, that class must either be declared abstract, or it must provide concrete definitions of all methodsdeclared in and inherited into all of the interfaces that it implements. If the class is declared abstract, its subclasses must provide concrete definitions ofthe interface methods.

A concrete definition of an interface method

The interface named X in this program declares a method named intfcMethod . The class named A provides a concrete definition of that method.

(The minimum requirement for a concrete definition is a method that matches the method signature and has an empty body.)

Storing object's reference as an interface type

The interesting part of the program is shown in the following code fragment.

void doIt(){ Base myVar1 = new Base();myVar1.inherMethod(); X myVar2 = new A();myVar2.intfcMethod(); System.out.println("");}//end doIt()

The above fragment instantiates a new object of the class named A , and saves a reference to that object in a reference variable of the declared type X .

How many ways can you save an object's reference?

Recall that a reference to an object can be held by a reference variable whose type matches any of the following:

  • The class from which the object was instantiated.
  • Any superclass of the class from which the object was instantiated.
  • Any interface implemented by the class from which the object was instantiated.
  • Any interface implemented by any superclass of the class from which the object was instantiated.
  • Any superinterface of the interfaces mentioned above.

Save object's reference as implemented interface type

In this program, the type of the reference variable matches the interface named X , which is implemented by the class named A .

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
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
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
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
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
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
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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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