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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.

Discussion

We will start with a quiz

I am going to begin this module with a quiz just to make sure that you are still awake. Is the following statement Trueor False?

The TreeSet class is a direct implementation of the Collection interface.

The answer is False.

The TreeSet class is not a direct implementation of the Collection interface. Rather, the TreeSet class is a direct implementation of the SortedSet interface. The SortedSet interface extends the Set interface, and the Set interface extends the Collection interface.

The interface hierarchy for the Java Collections Framework is shown below:

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

As you learned in an earlier module, the Java Collections Framework doesn't have a single root. As shown above, there are two distinct trees in theframework -- The Collection hierarchy and the Map hierarchy.

The root of the Collection hierarchy

The Collection interface is the root of the collection hierarchy. The Java Collections Framework doesn't provide any direct implementations of the Collection interface. All of the implementations of the interfaces in the Collection hierarchy implement one of the sub-interfaces of the Collection interface.

What does Oracle say about this?

Here is what the Oracle documentation has to say on the topic of the Collection interface:

"The SDK does not provide any direct implementations of this interface: it provides implementations of more specific sub-interfaces like Set and List . This interface is typically used to pass collections around and manipulate them wheremaximum generality is desired."

The Oracle documentation also states:

"Bags or multisets (unordered collections that may contain duplicate elements) should implement this interface directly."

What about duplicate elements?

Some implementations of Collection allow duplicate elements, and others do not. Implementations of the List interface (such as ArrayList ) allow duplicate elements. Implements of Set and SortedSet (such as TreeSet ) do not allow duplicate elements. This was illustrated in an earlier module.

A sample program in that earlier module created two collection objects and applied the polymorphic add method to add the same elements to each collection. One of the collection objects was of type ArrayList , and the other collection object was of type TreeSet . The elements added to each collection contained one pair of duplicate elements. The duplicate elementwas automatically excluded from the TreeSet object, but was retained in the ArrayList object.

What is a set?

According to Oracle, a Set is a "collection that contains no duplicate elements ... this interface models the mathematical set abstraction."

An object of type Set is typically used to model collections such as Social Security numbers, where duplicates are not allowed.

What is a list?

Also according to Oracle, a List is "An ordered collection (also known as a sequence). The user of this interface has precise control over where in thelist each element is inserted. The user can access elements by their integer index (position in the list), and search for elements in the list."

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
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
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
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
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
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
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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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