The ordering maintained by a set must be with equals mcq

The ordering maintained by a set must be ____ with equals if it is to correctly implement the Set interface. Fill in the blank with the correct option:

A) TreeSet
B) LinkedHashSet
C) HashSet
D) StackSet

Answer: C) HashSet

Explanation: The correct answer is HashSet. The ordering maintained by a set must be consistent with equals if it is to correctly implement the Set interface. In the context of HashSet, there is no explicit ordering of elements, but the equality (and hence the hash code) of the elements determines their placement in the set. If the hash codes are inconsistent with equals, the set will not behave correctly.

Why the other options are incorrect:

• A) TreeSet: The TreeSet maintains elements in a sorted order based on their natural ordering or a comparator provided at set creation time. The consistency requirement with equals is crucial for TreeSet to avoid duplicate elements, but the question is more generic and applies to all sets, not just sorted ones.
• B) LinkedHashSet: The LinkedHashSet maintains insertion order of the elements. While it uses a combination of hash table and linked list, the primary concern for consistency with equals applies to all hash-based collections, including HashSet.
• D) StackSet: There is no StackSet in the standard Java Collections Framework, making this option invalid.