CertPal

Sets:

A Set is a collection that contains no duplicate elements. Sets are collections where no two elements are the same, which means that element1.equals(element2) should never return true. Also at most one element in a set can be null and no more.

A Set. Duplicates are not allowed and at most one null element is allowed

Sorted Sets:

A SortedSet is a set which sorts and maintains the ordering of its elements. Elements will be ordered by their natural ordering or by the use of a Comparator (if the developer provides one). A Comparable interface can help define the ordering for elements. For example a String’s natural ordering will dictate that elements be ordered this way “a”, “b”, “c” etc. The way in which elements are ordered in a Sorted data structure can be redefined by using the Comparator interface.