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Revised: Tue Apr 05 15:46:03 CDT 2016
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This module is one in a collection of modules on Java Collections designed for teaching ITSE2321 - Object-Oriented Programming (Java) at Austin Community College in Austin, TX.
This module contains review questions and answers keyed to the module titled Java4040: Purpose of Framework Implementations and Algorithms .
Once you study that module, you should be able to answer the review questions in this module.
The questions and the answers in this module are connected by hyperlinks to make it easy for you to navigate from the question to the answer and back again.
True or False? At least three things are included in the Java Collections Framework:
True or False? The Collections Framework provides at least nine concrete implementations of the interfaces in the framework.
True or False? The implementations in the Java Collections Framework are the concrete definitions of the classes that implement the core collection interfaces .
True or False? Concrete implementations in the Java Collections Framework are provided by at least the following classes.
True or False? Algorithms are methods (not necessarily exposed) that provide useful capabilities, such as searching and sorting.
True or False? The contract for the contains method requires that the method:
True or False? 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.
True or False? When you call the contains method on a Collection object, the manner in which the search will be performed will be the same regardless of the class from which the object wasinstantiated.
The program shown in Listing 1 will be used for several different questions.
| Listing 1 . Used for several questions. |
|---|
/*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 |
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