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class A extends Base implements X{ public void inherMethod(){System.out.print( " A-inherMethod ");}//end inherMethod()public void intfcMethodX(){ System.out.print("A-intfcMethodX "); }//end intfcMethodX()}//end class A class B extends Base implements X{public void inherMethod(){ System.out.print(" B-inherMethod "); }//end inherMethod()public void intfcMethodX(){System.out.print("B-intfcMethodX "); }//end intfcMethodX()}//end class B

Concrete definitions of the interface method

As before, these methods provide concrete definitions of the method named intfcMethodX , which is declared in the interface named X .

An array of references of type Object

The interesting portion of this program begins in the following fragment, which instantiates and populates a two-element array object (container) of type Object . (In the sense of this discussion, an array object is a container, albeit a very simple one.)

void doIt(){ Object[]myArray = new Object[2];myArray[0] = new A();myArray[1] = new B();

Store object references of type A and B as type Object

Because the container is declared to be of type Object , references to objects instantiated from any class can be stored in the container. The code in theabove fragment instantiates two objects, (one of class A and the other of class B ), and stores the two object's references in the container.

Cannot call interface method as type Object

The code in the for loop in the next fragment attempts to call the method named intfcMethodX on each of the two objects whose references are stored in the elements of the array.

for(int i=0;i<myArray.length;i++){ myArray[i].intfcMethodX(); }//end for loopSystem.out.println(""); }//end doIt()

This produces the following compiler error under JDK 1.3:

Ap136.java:24: cannot resolve symbol symbol : method intfcMethodX ()location: class java.lang.ObjectmyArray[i].intfcMethodX();

What methods can you call as type Object?

It is allowable to store the reference to an object instantiated from any class in a container of the type Object . However, the only methods that can be directly called (without a cast and not using generics) on that reference are the following eleven methods. These methods are defined in the class named Object :

  • clone ()
  • equals(Object obj)
  • finalize()
  • getClass()
  • hashCode()
  • notify()
  • notifyAll()
  • toString()
  • wait()
  • wait(long timeout)
  • wait(long timeout,int nanos)

Overridden methods

Some, (but not all) , of the methods in the above list are defined with default behavior in the Object class, and are meant to be overridden in new classes that you define. This includes the methods named equals and toString .

Some of the methods in the above list, such as getClass , are simply utility methods, which are not meant to be overridden.

Polymorphic behavior applies

If you call one of these methods on an object's reference (being stored as type Object) , polymorphic behavior will apply. The version of the method overridden in, or inherited into, the class from which the object wasinstantiated will be identified and executed.

Questions & Answers

Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
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
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
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
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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