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If you define any constructors, the default constructor will no longer be provided automatically. Therefore, if a constructor that takes no arguments willever be needed for your new class, and you define one or more parameterized constructors, you must define the noarg constructor when you define your class.

A parameterized constructor for Worker

The class named Worker in this program defines a constructor that receives two incoming parameters, one of type int and the other of type boolean . It uses those two incoming parameters to initialize two instance variables of the new object.

Oops!

However, it does not define a constructor with no arguments in the formal argument list (commonly called a noarg constructor) .

Calling the missing noarg constructor

The following code in the main method of the controlling class attempts to instantiate two objects of the Worker class. The first call of the constructor passes no parameters to the constructor. Thus, it requires a noarg constructor in order to instantiate the object.

public class Ap118{ public static void main(String args[]){new Worker().display(); new Worker(5,true).display();System.out.println(); }//end main()}//end class Ap118

A compiler error

Since there is no constructor defined in the Worker class with an empty formal argument list (and the default version is not provided) , the program produces the following compiler error.

Ap118.java:11: cannot resolve symbol symbol : constructor Worker() location: class Workernew Worker().display();

Back to Question 9

Answer 8

C. 0 0.0 false

Explanation 8

All instance variables are initialized to default values

All instance variables are automatically initialized to default values if the author of the class doesn't take explicit steps to cause them to initialized toother values.

The default values

Numeric variables are automatically initialized to zero, while boolean variables are automatically initialized to false. Instance variables of type char are initialized to a Unicode value with all 16 bits set to zero. Reference variables are initialized to null.

Back to Question 8

Answer 7

A. Compiler Error

Explanation 7

Pushing the compiler beyond its limits

Compared to many programming environments, the Java compiler is very forgiving. However, there is a limit to how far even the Java compiler iswilling to go to keep us out of trouble.

Initializing the value of a static variable

We can initialize the value of a static variable using an initialization expression as follows:

public static final MY_CONSTANT = initialization expression;

Important point

It is necessary for the compiler to be able to evaluate the initialization expression when it is encountered.

Illegal forward reference

This program attempts to use an initialization expression that makes use of the value of another static variable (myPI) that has not yet been established at that point in the compilation process. As a result, the program produces thefollowing compiler error under JDK 1.3.

Ap116.java:18: illegal forward reference = 2 * myPI;^

Questions & Answers

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
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
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
How can I make nanorobot?
Lily
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
how can I make nanorobot?
Lily
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
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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