HashSet

/*Dear Fellows, on compiling this program I am getting an output
C:\jdk1.2.1\bin>java SetApp
The size of the set is: 5
a
test
This
is
null
I think Output should have been
This
is
a
null
Test
Can any colleague kindly guide me, as to why the program output is not as I had expected it to be*/
import java.util.*;
public class SetApp {
public static void main(String args[]){
HashSet set = new HashSet();
set.add("This");
set.add("is");
set.add("is");
set.add("a");
set.add("a");
set.add(null);
set.add("test");
displaySet(set);
}
static void displaySet(HashSet set) {
System.out.println("The size of the set is: "+set.size());
Iterator i = set.iterator();
while(i.hasNext()){
Object o = i.next();
if(o == null) System.out.println("null");
else System.out.println(o.toString());
}
}
}

HashSet does not make any guarantee about the order of objects because it uses hash codes to locate objects.
Bill

YOu can use the Comparator function to order the elements in the HashSet by using Collections.sort or you can use Sortedset ...

Originally posted by ZEESHAN AZIZ:
/*Dear Fellows, on compiling this program I am getting an output
C:\jdk1.2.1\bin>java SetApp
The size of the set is: 5
a
test
This
is
null
I think Output should have been
This
is
a
null
Test
Can any colleague kindly guide me, as to why the program output is not as I had expected it to be*/
import java.util.*;
public class SetApp {
public static void main(String args[]){
HashSet set = new HashSet();
set.add("This");
set.add("is");
set.add("is");
set.add("a");
set.add("a");
set.add(null);
set.add("test");
displaySet(set);
}
static void displaySet(HashSet set) {
System.out.println("The size of the set is: "+set.size());
Iterator i = set.iterator();
while(i.hasNext()){
Object o = i.next();
if(o == null) System.out.println("null");
else System.out.println(o.toString());
}
}
}