// illustrates inheritance and use of this

import java.util.TreeSet;
import java.util.Iterator;

class TreeSetHelper2 extends TreeSet   // inheritance
 {
    public void print()
     {Iterator it = this.iterator();   // and this
      while (it.hasNext())
       {System.out.println(it.next());
       }
      }
     }
**************************************

import java.io.*;

public class TreeSetDriver2
{

public static void main(String[] args) throws IOException
 {TreeSetHelper t = new TreeSetHelper();
  t.add("Mary");
  t.add("Tom");
  t.add("Ellen");
  t.add("Jack");
  t.add("Joe");
  t.add("Kelly");
  t.add("Nancy");
  t.add("Bob");
  t.print();
  t.remove("Jack");
  System.out.println();
  t.print();
  }
  }