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Display the collection's contents

Then, as before, the code in Listing 4 gets an iterator and uses it to access and display the contents of the ArrayList collection.

The ArrayList class implements the List interface, which does not prohibit duplicate elements, and does not maintain its elements in sortedorder. Therefore, in this case, the following text was displayed:

44321

All five element values are displayed, including the duplicate, in the order in which they were added to the list.

The important point

The important point is that although the fillIt method calls the same method name ( add ) on each of the collection objects, the behavior of that method is different in each case. In both cases, the behavior isappropriate for the underlying data structure. Furthermore, the underlying data structure isn't even known to the fillIt method.

No duplicate elements in ascending order

In the first case, where the underlying data structure was a TreeSet object (type SortedSet ), the duplicate element was eliminated, and the elements were stored so as to be accessible in ascending order.

Duplicates allowed with no sorting

In the second case, where the underlying data structure was an ArrayList object (type List ), all five elements, including the duplicate element were stored in the collection. Furthermore, they were stored and laterretrieved in the same order in which they were added.

Structure of the core interfaces

The core collection interfaces in the Java Collections Framework do not all extend from a common root interface.

Rather, the inheritance structure of the core interfaces is shown below. Indentation is used to indicate the parent-child relationships among the interfaces.

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

A Map is not a true Collection

As you can see, that there is no common root interface. Rather, there are two distinct trees, one rooted by Collection and the other rooted by Map . According to The Java Tutorial from Oracle, "a Map is not a true Collection." I will have more to say about this in a future module.

Some operations are optional

Every class that implements an interface in the tree rooted in Collection is not required to support all of the methods (operations) declared in the Collection interface.

Rather, some of the methods in the Collection interface are designated as "optional operation" in the documentation. (See the list of optional methods for the Collection interface below.)

According to the contract for the Collections Framework, if a given implementation doesn't support a specific method, it must throw an UnsupportedOperationException . The author of the implementation is responsible for providing documentation that identifies the optional operationsthat the implementation does and does not support.

Support for optional operations

This should not be an issue unless you are either defining your own implementation, or using an implementation defined by someone other than theprogrammers at Oracle. All of the general-purpose implementations from Oracle appear to support all of the optional operations.

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 ?
s.
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.
Harper
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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
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
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
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
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
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
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
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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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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