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Listing 5 . The Comparator.
class TheComparator implements Comparator,Serializable{ public int compare(Object o1,Object o2){if(!(o1 instanceof String)) throw new ClassCastException();if(!(o2 instanceof String)) throw new ClassCastException();int result = ((String)o1).compareTo(((String)o2)); return result*(-1);}//end compare() }//end class TheComparator

I have presented and explained this class in previous modules, so I won't discuss it in detail again here. Suffice it for now to say that an objectinstantiated from this class will induce the list to be sorted into reverse natural order .

Display the sorted list

The code in Listing 6 gets and uses an iterator to display the contents of the sorted list.

Listing 6 . Display the sorted list.
iter = ref.iterator(); while(iter.hasNext()){System.out.print(iter.next() + " "); }//end while loop

The output produced by the code in Listing 6 is shown below:

Tom TOM Joe JOE Bill BILL

As you can see, this is reverse natural order as induced by the Comparator object.

Run the program

I encourage you to copy the code from Listing 1 . Paste the code into your Java editor. Thencompile and execute it.

Run the program and observe the results. Experiment with the code. Make changes, run the program again, and observe the results of your changes. Make certain that youcan explain why your changes behave as they do.

Summary

In this module, I taught you how to use the sort method of the Collections class along with a Comparator object to sort the contents of a list.

By using this approach, you can sort the contents of list according to any set of comparison rules that you can program into the compare method of the Comparator object.

Furthermore, the ability to sort the list is independent of the actual implementation of the list, so long as the list properly implements the List interface. For example, the same Comparator object (and the same code) can be used to sort an ArrayList , a LinkedList , or a Vector , producing the same results regardless of which class the list object isinstantiated from.

What's next?

In the next module, I will show you how to use a Comparator created by the reverseOrder method of the Collections class to sort a list into reverse natural order . I will also show you how to use the reverse method of the Collections class to reverse the order of the elements in a list.

Miscellaneous

This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Java4130: The Comparator Interface, Part 5
  • File: Java4130.htm
  • Published: 05/07/13
Disclaimers:

Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.

I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.

In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.

Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.

-end-

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
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