Java Programming by Pearson

The Collection Framework • 551

Explanation: This program is simple to understand. One important thing to note here is that elements of

HashSet are not ordered and duplicate elements are displayed only once.

18.6.2 TreeSet Class

This class implements the Set and SortedSet interface. As the name implies, the class uses the tree

for storage of its elements. The TreeSet implementation is useful when one needs to extract elements from

a collection in a sorted manner. In order to work properly, elements added to a TreeSet must be sortable.

A tree knows how to keep elements of the java.lang wrapper classes sorted. It is generally faster to add ...