<< Chapter < Page Chapter >> Page >

The String class implements the Comparable interface. Therefore, objects instantiated from the String class have a natural ordering when placed in a collection.

Because the compareTo method of the String class, (which implements the Comparable interface) considers upper-case and lower-case characters to be different, there were no duplicate elements added to thecollection when only the compareTo method was used to compare elements. The six String objects were simply arranged so that the iterator would return references to those objects in sorted order. This produced the output shownbelow:

BILL Bill JOE Joe TOM Tom

A TreeSet with a Comparator

The code shown in Listing 4 was used to instantiate a new TreeSet object. A Comparator object's reference was passed to the TreeSet constructor. The Comparator object (instead of the compareTo method) was subsequently used for comparing and controlling the sorting order of the elements in the TreeSet collection.

Listing 4 . A TreeSet with a Comparator.
ref = new TreeSet(new TheComparator());Populator.fillIt(ref);iter = ref.iterator(); while(iter.hasNext()){System.out.print(iter.next() + " "); }//end while loop

The code in Listing 4 was also used to populate the collection, and to display the contents of the collection after it was populated.

Populating the TreeSet collection

As before, the fillIt method shown in Listing 5 was used to populate the collection. The same six names as before were added to the TreeSet collection. However, the result of adding those six names was determined by the behavior of the compare method in the Comparator object used by the TreeSet object for managing the collection. (Three of the names were rejected as duplicates.)

Listing 5 . Populating the TreeSet collection.
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()

Beginning of the Comparator class

The code in Listing 6 shows the beginning of the class from which the Comparator object was instantiated. Note that this class implements the Comparator interface, and therefore defines a concrete version of the method named compare .

Listing 6 . Beginning of the Comparator class.
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();

Listing 6 doesn't contain the interesting part of this class. The code in Listing 6 simply throws an exception if the compare method receives any incoming parameters of types other than String .

The interesting code

The interesting code in the method named compare is shown in Listing 7 .

Listing 7 . The interesting code in the compare method.
int result = ((String)o1).toUpperCase().compareTo(((String)o2). toUpperCase());return result; }//end compare()

The code in Listing 7 makes use of two methods of the String class to compare the two incoming objects.

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
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





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
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Object-oriented programming (oop) with java' conversation and receive update notifications?

Ask