Programs

import java.util.*;

/*
class Example
{
 int x;
 Example(){}
 Example(int x){this.x = x;}
}

class AddingCustomObjects
{
 public static void main(String[] args)
 {
  TreeSet ts = new TreeSet();
  ts.add(new Example());
  //ts.add(new Example());     RE: Exception in thread "main" java.lang.ClassCastException: Example cannot be                                  cast to java.lang.Comparable
  //ts.add(new Example(20));
 }
}


public boolean add(Object obj)
{
 if (this.size() >1)
 {
  Comparable c = (Comparable)obj;
  c.compateTo(tsItr.next());
 }
}
*/

class Example implements Comparable
{
 int x;
 
 Example(){}
 Example(int x){this.x = x;}

 public int compareTo(Object obj)
 {
  Example e = (Example)obj;
  
  //System.out.println(x);
  //System.out.println(e.x);

  return e.x - this.x;
 }

 public String toString()
 {
  return ""+x;
 }
}

class AddingCustomObjects
{
 public static void main(String[] args)
 {

  TreeSet ts = new TreeSet();

  ts.add(new Example());
  ts.add(new Example(20));
  ts.add(new Example());
  ts.add(new Example(5));
  ts.add(new Example(30));
  ts.add(new Example(20));
  ts.add(new Example());

  System.out.println(ts.size());
  System.out.println(ts);
 }
}