Question

How to remove duplicates from List?

(a) HashSet<String> listToSet = new HashSet<String>(duplicateList);

(b) HashSet<String> listToSet = duplicateList.toSet();

(c) HashSet<String> listToSet = Collections.convertToSet(duplicateList);

(d) HashSet<String> listToSet = duplicateList.getSet();

The question was asked in an international level competition.

This is a very interesting question from Data Structures-List in portion java.util – The Collections Framework of Java

Answer 1

Correct option is (a) HashSet<String> listToSet = new HashSet<String>(duplicateList);

Explanation: Duplicate elements are allowed in List. Set contains unique objects.