Java Code:
import java.util.TreeSet;

/**
 * TreeSet Demo.
 * 
 * @author Ian F. Darwin, http://www.darwinsys.com/
 * @version $Id: TreeSetDemo.java,v 1.3 2004/02/09 03:34:04 ian Exp $
 */
public class TreeSetDemo {
  public static void main(String[] argv) {
    //+
    /*
     * A TreeSet keeps objects in sorted order. We use a Comparator
     * published by String for case-insensitive sorting order.
     */
    TreeSet tm = new TreeSet(String.CASE_INSENSITIVE_ORDER);
    tm.add("Gosling");
    tm.add("da Vinci");
    tm.add("van Gogh");
    tm.add("Java To Go");
    tm.add("Vanguard");
    tm.add("Darwin");
    tm.add("Darwin"); // TreeSet is Set, ignores duplicates.

    // Since it is sorted we can ask for various subsets
    System.out.println("Lowest (alphabetically) is " + tm.first());
    // Print how many elements are greater than "k"
    System.out.println(tm.tailSet("k").toArray().length
        + " elements higher than \"k\"");

    // Print the whole list in sorted order
    System.out.println("Sorted list:");
    java.util.Iterator t = tm.iterator();
    while (t.hasNext())
      System.out.println(t.next());
    
  }
}