import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
class SetDemo {
public static void main(String[] args) {
String[] letters = { "A", "B", "C", "D", "E" };
Set s = new HashSet();
for (int i = 0; i < letters.length; i++)
s.add(letters[i]);
if (!s.add(letters[0]))
System.out.println("Cannot add a duplicate.\n");
Iterator iter = s.iterator();
while (iter.hasNext())
System.out.println(iter.next());
System.out.println("");
SortedSet ss = new TreeSet();
for (int i = 0; i < letters.length; i++)
ss.add(letters[i]);
if (!ss.add(letters[0]))
System.out.println("Cannot add a duplicate.\n");
iter = ss.iterator();
while (iter.hasNext())
System.out.println(iter.next());
}
}
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