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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

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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.
Do you know which machine is used to that process?
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
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