SortedSet.headSet

Returns a view of the portion of this set whose elements are strictly less than <tt>toElement</tt>. The returned set is backed by this set, so changes in the returned set are reflected in this set, and vice-versa. The returned set supports all optional set operations that this set supports.

<p>The returned set will throw an <tt>IllegalArgumentException</tt> on an attempt to insert an element outside its range.

@param toElement high endpoint (exclusive) of the returned set @return a view of the portion of this set whose elements are strictly less than <tt>toElement</tt> @throws ClassCastException if <tt>toElement</tt> is not compatible with this set's comparator (or, if the set has no comparator, if <tt>toElement</tt> does not implement {@link Comparable}). Implementations may, but are not required to, throw this exception if <tt>toElement</tt> cannot be compared to elements currently in the set. @throws NullPointerException if <tt>toElement</tt> is null and this set does not permit null elements @throws IllegalArgumentException if this set itself has a restricted range, and <tt>toElement</tt> lies outside the bounds of the range