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The Collections Framework is defined by a set of interfaces and associated contracts, and provides concrete implementations of the interfaces for the mostcommon data structures. In addition, the framework also provides several abstract implementations, which are designed to make it easier for you to createnew and different implementations while still maintaining the structural polymorphic integrity of the framework.


The code in this series of modules is written with no thought given to Generics . As a result, if you copy and compile the code, you will probably get warnings about unchecked or unsafe operations .

While you will ultimately need to understand how to use Generics, that is a very complex topic. An understanding of Generics is beyond the scope of thiscourse. Therefore, for purposes of this course, you can simply ignore those warnings.


A quiz

Let's begin with a little quiz to establish your baseline knowledge of the Collections Framework. Take a look at the program in Listing 6 near the end of this module. Which of the following is the output produced by that program?

  • A. Compiler Error
  • B. Runtime Error
  • C. 44321
  • D. 12344
  • E. 1234
  • F. None of the above.

If your answer was 1234 (and it wasn't a guess) then you may already know quite a lot about the use of the Collections Framework. If not, keep reading to begin learning aboutthe framework.

Elements of the Framework are easy to use

This simple introductory program is not intended to do anything useful. Instead, it was designed to illustrate several important features of theframework, including the ease with which elements of the framework can be reused in your programs.

Don't reinvent the wheel

As many of you already know, I am a college professor. I specialize in teaching OOP using Java. In the past, many college courses in Data Structures (often referred to as CS2 courses) have emphasized the concept of reinventing the wheel . Students were required to learn how to reinvent a variety of complex data structures in order to successfully complete the course.

Hopefully, with the conversion of these CS2 courses to Java OOP, the emphasis will change to reuse instead of reinvent .

Collections Framework encourages reuse

The Java Collections Framework is designed to encourage programmers to reuse existing interfaces and classes instead of inventing new ones. In the event thatit is necessary to invent a new class or interface, the programmer is encouraged to integrate it into the framework in a polymorphic manner.

Sample program

I am going to provide a brief discussion of the sample program (shown in Listing 6 ) in this module. Later, I will provide more detailed discussions of many of the features used in that program.

Interesting code fragments

I will break this program down and discuss it in fragments.

An object of the TreeSet class

The code fragment in Listing 1 instantiates an object of the TreeSet class and stores the object's reference in a reference variable of type Collection named ref .

Listing 1 . A new object of the TreeSet class.
class Worker{ public void doIt(){Collection ref = new TreeSet();

Questions & Answers

what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
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.
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
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
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
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
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
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.
what is the actual application of fullerenes nowadays?
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.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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