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Revised: Wed Apr 06 08:58:40 CDT 2016
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This module contains review questions and answers keyed to the module titled Java4050: Core Collection Interfaces .
The questions and the answers are connected by hyperlinks to make it easy for you to navigate from the question to the answer and back again.
The program in Listing 1 may be referred to by several different questions.
| Listing 1 . Program named Ap401. |
|---|
import java.util.TreeSet;
import java.util.ArrayList;import java.util.Collection;
import java.util.Iterator;public class Ap401{
public static void main(String args[]){
new Worker().doIt();}//end main()
}//end class Ap401class Worker{
public void doIt(){Collection ref = new TreeSet();
Populator.fillIt(ref);Iterator iter = ref.iterator();
while(iter.hasNext()){System.out.print(iter.next());
}//end while loopSystem.out.print(" ");
ref = new ArrayList();Populator.fillIt(ref);
iter = ref.iterator();while(iter.hasNext()){
System.out.print(iter.next());}//end while loop
System.out.println();}//end doIt()
}// end class Workerclass Populator{
public static void fillIt(Collection ref){ref.add(new Integer(4));
ref.add(new Integer(4));ref.add(new Integer(3));
ref.add(new Integer(2));ref.add(new Integer(1));
}//end fillIt()}//end class populator |
Which of the following does Listing 1 produce as an output?
True or False? The basic purpose of the core collection interfaces in the Java Collections Framework is to allow collections to be manipulatedwithout regard for how the collections are implemented.
True or False? There is only one way to implement a list.
True or False? If two lists are implemented in different ways, but both satisfy the requirements of the core collection interfaces, they can each bemanipulated the same way regardless of the details of their implementation.
True or False? A collection of type TreeSet and a collection of type ArrayList are instantiated in the program in Listing 1 . Each of the collections is viewed as being of the interface type Collection .
True or False? Given the TreeSet and ArrayList classes, only the TreeSet class implements the Collection interface. (See the Java documentation.)
True or False? Both the TreeSet class and the ArrayList class inherit an abstract method named add from the Collection interface.
True or False? Given that both the TreeSet class and the ArrayList class inherit an abstract method named add from the Collection interface, each class is required to define a concrete version of the add method with the same behavior.
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