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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

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
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
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
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
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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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