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This module takes a preliminary look at arrays and strings. More in-depth discussions will be provided in future modules.

Revised: Mon Mar 28 16:20:59 CDT 2016

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This module takes a preliminary look at arrays and strings. More in-depth discussions will be provided in future modules. For example, you will find a more in-depth discussions of array objects in the followingmodules:

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the Figuresand Listings while you are reading about them.


  • Figure 1 . Formats for declaring a reference variable for an array object.
  • Figure 2 . Allocating memory for the array object.
  • Figure 3 . Declaration and instantiation can be separated.
  • Figure 4 . General syntax for combining declaration and instantiation.
  • Figure 5 . An example of array indexing syntax.
  • Figure 6 . The use of the length property in the conditional clause of a for loop.
  • Figure 7 . A string literal.
  • Figure 8 . String concatenation.
  • Figure 9 . Declaring and instantiating a String array.
  • Figure 10 . Allocating memory to contain the String objects.



The first step

The first step in learning to use a new programming language is usually to learn the foundation concepts such as variables, types,expressions, flow-of-control, arrays, strings, etc. This module concentrates on arrays and strings.

Array and String types

Java provides a type for both arrays and strings from which objects of the specific type can be instantiated. Once instantiated, the methodsbelonging to those types can be called by way of the object.


Arrays and Strings

Java has a true array type and a true String type with protective features to prevent your program from writing outside the memorybounds of the array object or the String object. Arrays and strings are true objects.

Declaring an array

You must declare an array before you can use it. (More properly, you must declare a reference variable to hold a reference to the array object.) In declaring the array, you must provide two important pieces of information:

  • the name of a variable to hold a reference to the array object
  • the type of data to be stored in the elements of the array object

Different declaration formats

A reference variable capable of holding a reference to an array object can be declared using either format shown in Figure 1 . (I personally prefer the first option because I believe it is more indicative ofthe purpose of the declaration. However, both options produce the same result -- a reference variable capable of storing a reference to an array object.)

Questions & Answers

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
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
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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