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Bill Joe Tom
False. The first time the fillIt method is called in Listing 1 , the TreeSet collection referred to by the incoming parameter named ref is populated with the following names in the following natural order for String objects. The String class implements the Comparable interface, and that is what determines the sorted order in this case.
BILL Bill JOE Joe TOM Tom
True.
None of the above.
The output produced by the program shown in Listing 1 is four lines long as shown below. (Note that the bullets shown below do not appear in the actual program output.)
| Listing 1 . Comparator03.java . |
|---|
//File Comparator03.java
//Copyright 2001 R.G.Baldwinimport java.util.*;
import java.io.Serializable;public class Comparator03{
public static void main(String args[]){
new Worker().doIt();}//end main()
}//end class Comparator03class Worker{
public void doIt(){Iterator iter;
Collection ref;System.out.println("Natural ordering");
ref = new TreeSet();Populator.fillIt(ref);
iter = ref.iterator();while(iter.hasNext()){
System.out.print(iter.next() + " ");}//end while loop
System.out.println();System.out.println("Comparator in use");
ref = new TreeSet(new TheComparator());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("Joe");
ref.add("Bill");ref.add("Tom");
ref.add("JOE");ref.add("BILL");
ref.add("TOM");}//end fillIt()
}//end class Populatorclass TheComparator
implements Comparator,Serializable{public int compare(Object o1,Object o2){
if(!(o1 instanceof String))throw new ClassCastException();
if(!(o2 instanceof String))throw new ClassCastException();
//Do an upper-case comparison
int result =((String)o1).toUpperCase().
compareTo(((String)o2).toUpperCase());
return result;}//end compare()
public boolean equals(Object o){if(!(o instanceof TheComparator))
return false;else return true;
}//end overridden equals()}//end class TheComparator |
This section contains a variety of miscellaneous information.
Financial : Although the Connexions site makes it possible for you to download aPDF file for this module at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, youshould be aware that some of the HTML elements in this module may not translate well into PDF.
I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version ofthe module.
In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale onAmazon.com showing me as the author. I neither receive compensation for those sales nor do I know who does receive compensation. If youpurchase such a book, please be aware that it is a copy of a module that is freely available on cnx.org and that it was made andpublished without my prior knowledge.
Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.
-end-
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