//class will have heterogenous objects ,

public class TreeExample{

public static void main(String[] args){

//we need a custom Comparator because the list can have Objects which will not implement Comparable.

java.util.TreeSet t1 = new java.util.TreeSet(new MyComparator());

t1.add("ABC");

t1.add(new StringBuffer("A"));

t1.add("ABT");

t1.add(new StringBuffer("B"));

t1.add("ABM");

t1.add(new StringBuffer("AA"));

t1.add("ACD");

t1.add(new StringBuffer("Aa"));

System.out.println(t1);

}

}

class MyComparator implements java.util.Comparator{

public int compare(Object obj1 , Object obj2){

String s1 = obj1.toString();

String s2 = obj2.toString();

int l1 = s1.length();

int l2 = s2.length();

if(l1 > l2){

return 1;

}

if(l1 < l2){

return -1;

}

else{

return s1.compareTo(s2);

}

}

}