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Collection data Joe Bill Tom JOE BILL TOM

As you can see, this is the same order in which the names were added to the collection by the fillIt method in Listing 4 .

The toArray method

The code in Listing 6 is new to this module. This code calls the toArray method on the Vector object to extract the contentsof the collection and store the elements in an array object of type Object .

Listing 6 . Call the toArray method.
array = ref.toArray();

(Recall that the variable named array was declared as a reference to an array object of type Object in Listing 1 .)

The contract

According to the documentation for the Vector class, this version of the toArray method:

"Returns an array containing all of the elements in this Vector in the correct order."

The documentation for the toArray method of the Collection interface is a little more verbose, reading partially as follows:

"Returns an array containing all of the elements in this collection. If the collection makes any guarantees as to what order its elements arereturned by its iterator, this method must return the elements in the same order.

Elements are returned in ascending index order

By default, the iterator for a Vector returns its elements in ascending index order. Therefore, the toArray method for a Vector object must return the elements in the same order.

A "safe" array

Also, according to Oracle:

"The returned array will be "safe" in that no references to it are maintained by this collection. ... The caller is thus free to modify thereturned array."

In the code in Listing 6 above, the returned reference to an array object is assigned to a reference variable that previously contained null. Following theexecution of the toArray method, that reference variable refers to an array object of type Object containing the same elements as the Vector collection, in ascending index order.

(Regarding the concept of a "safe" array, it is easy to demonstrate that the elements in the array refer to the same objects referred to by the elementsin the Vector. Thus, using the references stored in the array to modify the objects to which they refer also modifies the objects referred to by theelements stored in the Vector. In other words, the elements in the array are copies of the elements in the Vector. The elements in the array refer to theoriginal objects, and do not refer to copies (or clones) of those objects. As usual when dealing with multiple references to objects, care should be taken to avoidinadvertently corrupting those objects.)

Display the contents of the array

The code in Listing 7 passes the array object's reference to a method named display that displays the contents of the array in ascending index order.

Listing 7 . Display the contents of the array.
System.out.println("Raw array data"); display(array);

The output produced by the code in Listing 7 is as shown below:

Raw array data Joe Bill Tom JOE BILL TOM

As you can see, this is the same data, in the same order, as the contents of the collection displayed earlier.

(The method named display is a simple utility method that I won't discuss here because of its simplicity. You canview the display method in its entirety in Listing 1 .)

Questions & Answers

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
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
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
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
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
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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