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Back to Question 10

Answer 9

C. 10

Explanation 9

A setter and a getter

This is a very simple program that uses a setter (modifier or mutator) method named setX to set the value 10 in a property named x that is stored in an instance variable named y in an object instantiated from the class named NewClass ..

The program also uses a getter (accessor) method named getX to get and display the value of the property named x . (Note that according to JavaBeans design patterns, the name of the property isunrelated to the name of variable in which the property value is stored.)

Back to Question 9

Answer 8

D. 5

Explanation 8

Hide your data and expose your methods

For reasons that I won't go into here, good object-oriented design principles state that in almost all cases where an instance variable is not declared to be final , it should be declared private . (A final variable behaves like a constant.)

What is private access?

When an instance variable is declared private , it is accessible only by methods of the class in which it is defined. Therefore, the only way that the"outside world" can gain access to a private instance variable is by going through an (usually public ) instance method of the object.

Accessor, modifier, mutator, setter, and getter methods

Historically, methods that have been defined for the purpose of exposing private instance variables to the outside world have been referred to as accessor and modifier methods. (Modifier methods are also sometimes called mutator methods.)

(Note that since the advent of Sun's JavaBeans Component design patterns, these methods have also come to be known as getter methods and setter methods indeference to the design-pattern naming conventions for the methods.)

A private instance variable with an initializer

The class named NewClass declares a private instance variable named x and initializes its value to 2, as shown in the following code fragment:

private int x = 2;

Two constructors

The class contains both a noarg constructor and a parameterized constructor as shown in the following fragment:

public NewClass(){ }//end constructorpublic NewClass(int x){this.x = x; }//end constructor

Calling the noarg constructor

If an object of the class is instantiated by calling the noarg constructor, the initial value of 2 remains intact, and that object contains an instancevariable with an initial value of 2.

Calling the parameterized constructor

If an object of the class is instantiated by calling the parameterized constructor, the initial value of 2 is overwritten by the value of the incomingparameter to the parameterized constructor. In this case, that value is 5, because the object is instantiated by the following code fragment that passesthe literal value 5 to the parameterized constructor. Thus, the initial value of the instance variable in that object is 5.

NewClass obj = new NewClass(5);

A getter method

Because the instance variable named x is private , it cannot be accessed directly for display by the code in the makeObj method of the Worker class. However, the NewClass class provides the following public getter or accessor method that can be used to get the value stored in the instance variable.

Questions & Answers

what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor 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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