Get the least and greatest element in this TreeSet « TreeSet « Set « Collections

Return	Method	Summary
E	ceiling(E e)	Returns the least element in this set greater than or equal to the given element, or null if there is no such element.
E	floor(E e)	Returns the greatest element in this set less than or equal to the given element, or null if there is no such element.
E	higher(E e)	Returns the least element in this set strictly greater than the given element, or null if there is no such element.
E	lower(E e)	Returns the greatest element in this set strictly less than the given element, or null if there is no such element.