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False. In the output from Listing 1 , descending order means that names beginning with letters that are high in the alphabet occur before names beginning with letters that are lower inthe alphabet. In addition, names containing lower case characters appear before the same names containing only upper case characters.
True.
False. Even without the use of a Comparator object, the order would be incorrect. A TreeSet object requires its elements to be in either ascending natural order or in an order specified by a Comparator object. This program uses a Comparator object but it doesn't result in the order shown in the question.
Tom TOM Joe JOE Bill BILL
| Listing 1 . Comparator04.java. |
|---|
//File Comparator04.java
//Copyright 2001, R.G.Baldwinimport java.util.*;
import java.io.Serializable;public class Comparator04{
public static void main(String args[]){
new Worker().doIt();}//end main()
}//end class Comparator04class Worker{
public void doIt(){Iterator iter;
Collection ref;ref = new TreeSet(new TheComparator());
Populator.fillIt(ref);iter = ref.iterator();
while(iter.hasNext()){System.out.print(iter.next() + " ");
}//end while loopSystem.out.println();
}//end doIt()}// end class Worker
class 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 Populator
class 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();
int result = ((String)o1).compareTo(((String)o2));return result*(-1);
}//end compare()public boolean equals(Object o){
if(!(o instanceof TheComparator))return false;
else return true;}//end overridden equals()
}//end class TheComparator |
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