import java.util.TreeSet;

public class TreeSetDemo {

public static void main(String[] args) {

TreeSet t=new TreeSet();

//Elements are inserted according to default natural sorting Order

// "a"(97) > "A" (65)

/**

* while adding null in "non empty" tree set we need to compare null with other elements so it is

* null pointer exception

* but we can add null in "empty tree set" at 1st insertion no need to compare null with any another

* element

*/

t.add(null);// null insetion possible only once

t.add("A");

t.add("a");

t.add("B");

t.add("Z");

t.add("c");

// t.add(new Integer(90));//Heterogenous insetion not possible so error

System.out.println(t);

}

}