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D. Tom TOM Joe JOE Bill BILL

Similar to previous programs

The overall structure of this program is very similar to programs that I have discussed in previous modules. Therefore, I will concentrate on thoseaspects of this program that differentiate it from the programs in previous modules.

A new TreeSet object with a Comparator

The code in Listing 2 instantiates a new TreeSet object, by providing a reference to an anonymous object that implements the Comparator interface. That object is instantiated from the class named TheComparator . It is the Comparator object that will be of most interest to us in this module.

Listing 2 . A new TreeSet object with a Comparator.
Collection ref; ref = new TreeSet(new TheComparator());Populator.fillIt(ref); iter = ref.iterator();while(iter.hasNext()){ System.out.print(iter.next() + " ");}//end while loop

Populating the TreeSet collection

After the TreeSet object is instantiated, it is passed to a method named fillIt where the TreeSet collection is populated with the names of several people.

Display the contents of the TreeSet collection

As shown by the code in Listing 2 , after the TreeSet collection is populated, an Iterator is obtained for that collection and used to display the contents of the collection. The output produced by the programis shown below :

Tom TOM Joe JOE Bill BILL

Analyzing the contents of the TreeSet collection

We will need to compare this output with the names used to populate thecollection to appreciate the true significance of the use of the Comparator object.

At this point, it is worth pointing out that the six names contained in the collection are returned by the iterator in descending order , taking the significance of upper and lower case into account. In other words, namesbeginning with letters that are high in the alphabet occur before names beginning with letters that are lower in the alphabet. In addition, namescontaining lower case characters appear before the same names containing only upper case characters.

Method used to populate the collection

Listing 3 shows the method named fillIt that was used to populate the collection with references to six String objects. As you can see, the names weren't added in any particular order.

As you can also see by comparing Listing 3 with the output shown above , all six names that were added to the collection were displayed in the output, but ina different order from the order in which they were added. (Names with the same spelling but different case were not considered to be duplicates insofar asthe contract for the set was concerned.)

Listing 3 . The fillIt method.
public static void fillIt(Collection ref){ ref.add("Joe");ref.add("Bill"); ref.add("Tom");ref.add("JOE"); ref.add("BILL");ref.add("TOM"); }//end fillIt()

Implementing the Comparator interface

That brings us to the class from which the Comparator object was instantiated. The beginning portion of that class is shown in Listing 4 .

Listing 4 . Beginning of the class named TheComparator.
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();

Questions & Answers

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
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
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
what is nano technology
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what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
how to synthesize TiO2 nanoparticles by chemical methods
Zubear
how did you get the value of 2000N.What calculations are needed to arrive at it
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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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