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An IndexOutOfBounds exception

As a result, the program throws an IndexOutOfBounds exception. The error produced under JDK 1.3 looks something like the following:

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 2, Size: 2at java.util.ArrayList.RangeCheck (Unknown Source)at java.util.ArrayList.get (Unknown Source)at Worker.doIt(Ap147.java:27) at Ap147.main(Ap147.java:16)

Attempting to access an element with a negative index value would produce the same result.

An ArrayIndexOutOfBounds exception

A similar result occurs if you attempt to access an element in an ordinary array object outside the bounds of the index values determined by the size ofthe array. However, in that case, the name of the exception is ArrayIndexOutOfBounds .

Back to Question 7

Answer 6

B. Runtime Error

Explanation 6

The infamous NullPointerException

Interestingly, one of the first things that you read when you start reading Java books, is that there are no pointers in Java . It is likely that shortly thereafter when you begin writing, compiling, and executing simple Javaprograms, one of your programs will abort with an error message looking something like that shown below :

Exception in thread "main" java.lang.NullPointerException atWorker.doIt(Ap146.java:23) atAp146.main(Ap146.java:16)

What is a NullPointerException?

Stated simply, a NullPointerException occurs when you attempt to perform some operation on an object using a reference that doesn'trefer to an object.

That is the case in this program

The following code fragment declares a local reference variable and initializes its value to null .

void doIt(){ ArrayList ref = null;

(A reference variable in Java must either refer to a valid object, or specifically refer to no object (null). Unlike a pointer in C and C++, aJava reference variable cannot refer to something arbitrary.)

In this case, null means that the reference variable doesn't refer to a valid object.

No ArrayList object

Note that the code in the above fragment does not instantiate an object of the class ArrayList and assign that object's reference to the reference variable.

(The reference variable doesn't contain a reference to an object instantiated from the class named ArrayList , or an object instantiated from any class for that matter.)

Call a method on the reference

However, the code in the next fragment attempts to add a String object's reference to a nonexistent ArrayList object by calling the add method on the reference containing null.

ref.add("ABC ");

This results in the NullPointerException shown earlier .

What can you do with a null reference?

The only operation that you can perform on a reference variable containing null is to assign an object's reference to the variable. Any other attemptedoperation will result in a NullPointerException .

Back to Question 6

Answer 5

C. ABC DEF GHI

Explanation 5

The purpose of this program is to

  • Continue to illustrate the use of java packages, and
  • Illustrate the use of the Java import directive.

Program contains an import directive

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
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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