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Listing 4 . Get an Iterator object.
Iterator iter = ref.iterator();

The call to the iterator method on any Collection object returns an instance of a class that implements the Iterator interface. The Iterator object can be used to traverse the collection, gaining access to each element in order. (The concept of in order means different things for different kinds of collections. For a collection instantiated fromthe TreeSet class, in order means in ascending order.)

Again, don't know, don't care

Again, the author of the method that uses the Collection object doesn't need to know or care about the internal implementation of thecollection, or the implementation of the methods of the Iterator object. They simply do what they do, and can be used for their intended purpose.

An Iterator object acts as a doorkeeper

The Iterator interface declares three methods:

  • hasNext()
  • next()
  • remove()

You might say that an Iterator object acts as a doorkeeper for the collection object that it represents, providing access to the contents of thecollection in a very specific manner.

Traverse the collection

The code fragment in Listing 5 below shows how the first two of the above methods can be used to

  • Traverse the collection, accessing each of the object's elements in succession.
  • Display the value encapsulated in the object referred to by each element.

As mentioned earlier, when the collection is an object instantiated from the TreeSet class, access to the elements is provided in ascending order.

Listing 5 . Traverse the collection.
while(iter.hasNext()){ System.out.print(iter.next());}//end while loop

Four elements with no duplicates

At this point, the TreeSet object contains four elements, with no duplicates. Each of the elements is a reference to an object of type Integer . The code in the loop in Listing 5 causes each of those elements to be accessed and displayed in ascending order. This causes the following text to appear on thescreen:

1234

An editorial opinion

In my opinion, this is the kind of knowledge that a computer science student in a modern data structures course should be learning. This is a far departurefrom courses of the past where CS2 students were required to memorize the intricate details of how to implement various data structures.

What kind of knowledge is needed?

Does an architect need to understand the detailed inner workings of an air conditioning compressor to design a cooling system into a building? Ofcourse not!

However, the architect does need to know the tradeoffs among the available cooling systems in terms of initial cost, operating cost, size, efficiency, etc.

Does an audio technician need to understand the detailed inner workings of an electronic audio equalizer in order to construct an integrated audio system?Absolutely not! If that were a requirement, there would likely be very few audio systems in existence.

However, the audio technician does need to understand the tradeoffs among the various available audio equalizers.

The same concept applies to software design

Does an OOP software designer need to know the detailed inner workings of the various kinds of collection objects in order to use them effectively? No!

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
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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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