1. The underlying
data structure for TreeSet Is Balanced Tree
2. Duplicate objects are allowed.
3. Insertion order not preserved, but all objects will be
inserted according to some sorting order.
4. Heterogeneous objects are not allowed. If we are trying
to insert heterogeneous objects then we will get runtime
exception saying ClassCastException.
5. Null Insertion is allowed, but only once.
1. For Empty TreeSet as the first
element null insertion is possible. But After inserting
that null if we are trying to insert any another element
we will get NullPointerException.
2. For Non empty TreeSet if we are trying to insert Null
then we will get NullPointerException