Class CAst Exception

[ramya ray]

It will be great help if some one please explain why the below code throwing Class Cast Exception:

import java.util.*;
public class Test1{
public static void main(String a[]){
Set s = new TreeSet();
s.add(new Person(20));
s.add(new Person(10));
System.out.println(s);
}
}
class Person{
Person(int i){}
}

..

[Keith Lynn]

A TreeSet requires that either the elements you insert into have to be mutually comparable, i.e. the class definition implements the Comparable interface, or that you create the TreeSet with a Comparator that specifies how two objects in the set will be compared.

[ramya ray]

Thanks Keith ..i got it.