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int[] A[]; A = new int[2][3];

While it doesn't matter which location you use for the square brackets in the declaration, it does matter how many pairs of square brackets you place in thetwo locations combined. The number of dimensions on the array (if you want to think of a Java array as having dimensions) will equal the total number of pairs of empty square brackets in the declaration of the reference variable. Thus, in this case, the array is a two-dimensional arraybecause there is one pair of square brackets next to the type and another pair next to the variable name.

This program goes on to use nested for loops to populate the array and then to display the contents of the elements.

I personally don't use this syntax, and I hope that you don't either. However, even if you don't use it, you need to be able to recognize it when usedby others.

Back to Question 13

Answer 12

C. 1 2

Explanation 12

The length property

This program illustrates the use of the array property named length , whose value always matches the number of elements in the array.

As a Java programmer, you will frequently call methods that will return a reference to an array object of a specified type, but of an unknown length. (See, for example, the method named getEventSetDescriptors that is declared in the interface named BeanInfo .) This program simulates that situation.

Returning a reference to an array

The method named returnArray returns a reference to an array of type int having two elements. Although I fixed the size of the array in this example, I could just as easily have used a random number to set adifferent size for the array each time the method is called. Therefore, the doArrays method making the call to the method named returnArray has no way of knowing the size of the array referred to by the reference that it receivesas a return value.

All array objects have a length property

This could be a problem, but Java provides the solution to the problem in the length property belonging to all array objects.

The for loop in the method named doArrays uses the length property of the array to determine how many elements it needs to display. This is a very commonscenario in Java.

Back to Question 12

Answer 11

A. Compiler Error

Explanation 11

You cannot cast primitive array references

You cannot cast an array reference from one primitive type to another primitive type, even if the individual elements in the array are of a type thatcan normally be converted to the new type.

This program attempts to cast a reference to an array of type int[] and assign it to a reference variable of type double [].Normally, a value of type int will be automatically converted to type double whenever there is a need for such a conversion. However, this attempted cast produces the following compiler error under JDK1.3.

Ap074.java:19: inconvertible types found : int[]required: double[] double[]B = (double[])A;

Why is this cast not allowed?

I can't give you a firm reason why such a cast is not allowed, but I believe that I have a good idea why. I speculate that this is due to the fact that theactual primitive values are physically stored in the array object, and primitive values of different types require different amounts of storage. For example, the type int requires 32 bits of storage while the type double requires 64 bits of storage.

Questions & Answers

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
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
characteristics of micro business
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 ?
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.
what is the actual application of fullerenes nowadays?
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.
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.
is Bucky paper clear?
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.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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