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Drive home the point

I placed this question here to drive home the point that the methods declared in the Collection interface can be called on collection objects in a polymorphic manner.

That is to say, as a user of an object instantiated from a class that properly implements the Collection interface (according to the contracts of the Collections Framework) , you can call the methods declared in that interface on a reference to the object and be confident thatthe actual method that is called will be the version that is appropriate for the class from which the object was instantiated. This is polymorphic behavior.

In the event that you need to call a method that is not declared in the Collection interface (such as the get() method in Listing 4 above), you can pass the reference as one of the more specialized sub-interfaces of Collection , such as Set .

(Author's note: Once again, this document was originally written before the release of Generics. The use of the more specializedsub-interfaces described above may not be required if the program is re-written making proper use of Generics.)

Benefits of using the Collections Framework

The Java Tutorial from Oracle lists and explains the benefits of using the Java Collections Framework, including the following.

  • It reduces programming effort
  • It increases program speed and quality
  • It allows interoperability among unrelated APIs
  • It reduces the effort to learn and use new APIs
  • It reduces effort to design new APIs
  • It fosters software reuse

For a detailed explanation of these benefits, I am simply going to refer you directly to The Java Tutorial .

Run the program

I encourage you to copy the code from Listing 1 and paste it into a Java source code file. 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.


Let's recap some of what we have learned in this and the previousmodules.

The core collection interfaces in the Collections Framework are shown below.

  • Collection
    • Set
      • SortedSet
    • List
    • Queue
    • Deque
  • Map
    • SortedMap

The basic purpose of the core collection interfaces in the Java Collections Framework is to allow collections to be manipulated without regard for how thecollections are implemented, provided of course that the implementations comply with the contracts.

The framework provides at least the following nine concrete implementations (classes) of the interfaces shown above:

  • HashSet
  • TreeSet
  • LinkedList
  • ArrayList
  • Vector
  • HashMap
  • WeakHashMap
  • TreeMap
  • Hashtable

For example, the classes TreeSet and ArrayList are concrete implementations of the Collection interface as shown in the above list.

(Actually, they are concrete implementations of sub-interfaces of Collection. The Collections Framework doesn't provide any direct implementations of the Collectioninterface.)

A collection object instantiated from the class TreeSet and a collection object instantiated from the class ArrayList can each be viewed as being of the interface type Collection .

Methods having the same signatures can be used to manipulate either collection with confidence that the behavior of the method will be appropriatefor the actual type of collection involved.

The framework also provides the following incomplete implementations of the core interfaces:

  • AbstractSet
  • AbstractList
  • AbstractMap

The purpose of these implementations is to provide you with a starting point for defining your own concrete implementations for more specialized collections.


This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Java4040: Purpose of Framework Implementations and Algorithms
  • File: Java0440.htm
  • Published: 04/18/13

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.


Questions & Answers

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 ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
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.
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
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what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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