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Different classes, different implementations

You can safely call the contains method on any object instantiated from a class that properly implements the Collection interface, even if you don't know the actual type of the collection object.

The manner in which the search will be performed will probably differ from one concrete implementation of the interface to the next. For example, a TreeSet object will perform the search very rapidly with a time cost of only log(n) where n is the number of elements. On the other hand, for the same numberof elements, because of a different underlying data structure, a search on an ArrayList object will probably require more time than a search on a TreeSet object. As the number of elements increases, the difference in time cost between the two will also increase.

A sample program

Consider the sample program shown in Listing 1 . This program compares the search speed of the ArrayList class and the TreeSet class. A detailed discussion of the program follows Listing 1 .

Listing 1 . SpeedTest01.
/*File SpeedTest01 Copyright 2001 R.G.Baldwin**************************************/ import java.util.*;public class SpeedTest01{ public static void main(String args[]){ new Worker().doIt();}//end main() }//end class SpeedTest01class Worker{ public void doIt(){int size = 2000000; //Create a TreeSet objectCollection aTree = new TreeSet(); //Populate the TreeSet object with// random values. The add() method // for a set rejects duplicates.Random rnGen = new Random(); for(int ct = 0; ct<size; ct++){ aTree.add(new Double(rnGen.nextDouble()));}//end for loop //Create and populate an ArrayList// object with the same random // valuesCollection aList = new ArrayList(aTree); //Extract a value near the center// of the ArrayList object to use // as a test case.Object testVal = ((List)aList).get(size/2); //Search for the test value in each// of the collection objects. // Measure and display the time// required to perform the search // in each case.long start = new Date().getTime(); boolean found = aList.contains(testVal);long stop = new Date().getTime(); System.out.println(found + " " + (stop - start));start = new Date().getTime(); for(int x = 0; x<100000; x++){ found = aTree.contains(testVal);}//end for loop stop = new Date().getTime();System.out.println(found + " " + (stop - start)/100000.0); }//end doIt()}// end class Worker

Instantiate and populate a TreeSet object

The program begins by instantiating a TreeSet object and populating it with approximately 2,000,000 elements as shown in Listing 2 . The values encapsulated in the objects referred to by the elements in the collection areproduced by a random number generator.

Recall that the add method of a Set object rejects duplicate elements, so there may be fewer than 2,000,000 elements in the object after it ispopulated, depending on how many of the random values are duplicates.

Listing 2 . Beginning of the doIt method.
public void doIt(){ int size = 2000000;Collection aTree = new TreeSet(); Random rnGen = new Random();for(int ct = 0; ct<size; ct++){ aTree.add(new Double(rnGen.nextDouble()));}//end for loop

Questions & Answers

how can chip be made from sand
Eke Reply
is this allso about nanoscale material
Almas
are nano particles real
Missy Reply
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
Lohitha
where is the latest information on a no technology how can I find it
William
currently
William
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
has a lot of application modern world
Kamaluddeen
yes
narayan
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
Researchers demonstrated that the hippocampus functions in memory processing by creating lesions in the hippocampi of rats, which resulted in ________.
Mapo Reply
The formulation of new memories is sometimes called ________, and the process of bringing up old memories is called ________.
Mapo 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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