<< Chapter < Page Chapter >> Page >

Collection is an interface

The TreeSet class implements the SortedSet interface, which extends the Set interface, which in turn extends the Collection interface. Thus, a TreeSet object is a Collection . Therefore, a reference to a TreeSet object can be stored in a reference variable of type Collection , and can be treated as the generic type Collection .

What is a TreeSet object?

Among other things, in CS2 courses, we worry about the time and memory cost of a collection. According to Sun, the TreeSet class guarantees that the sorted set will be in ascending element order, and provides guaranteed log(n)time cost for the basic operations ( add , remove and contains ).

What does ascending element order mean?

Again, according to Sun, the elements will be sorted according to the natural order of the elements (see the Comparable interface) or by a comparator (see the Comparator interface) provided at the time the set is created. This depends on which overloaded constructor is used. I will have moreto say about these alternatives in a future module.

What does log(n) time cost mean?

I'm not going to try to explain the details of log(n) time cost here. Suffice it to say that the add , remove , and contains methods execute very fast. (I will have more to say about this is a future module.)

A TreeSet object is a Set

An object of the TreeSet class also is a Set . One of the characteristics of a Java Set (an object that implements the Set interface) is that it can contain no duplicate elements. Therefore, a TreeSet object can contain no duplicate elements. If the add method of a TreeSet object is called in an attempt to add a duplicate element, the element will not be added.

A TreeSet object is a SortedSet

The TreeSet class also implements the SortedSet interface. This guarantees that the contents of a TreeSet object will be in ascending element order, regardless of the order in which the elements are added. (In a future module, I will discuss how comparisons are made to enforce theordering of the elements.)

A TreeSet object is a Collection

Because an object of the TreeSet class is a Collection , a reference to such an object can be passed to any method that requires anincoming parameter of type Collection . The receiving method can call anymethod on that reference that is declared in the Collection interface . (I will discuss such methods in detail in future modules.)

Populate the Collection

The statement in Listing 2 passes the TreeSet object's reference to a method named fillIt , which is a static method of the Populator class. (The Populator class is a class of my own design whose only purpose is to illustrate the polymorphic behavior achieved using the CollectionsFramework.) The behavior of this method is to add elements to the incoming Collection object without regard for the actual type of the object (the class from which the object was instantiated).

Listing 2 . Populate the collection.
Populator.fillIt(ref);

At this point, I am going to discuss the fillIt method of the Populator class called in Listing 2 . The entire class definition of the Populator class, including the fillit method, is shown in Listing 3 .

Questions & Answers

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
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
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
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 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