HashMaps in Action: Tackling a Common Java Interview Challenge

Technical interviews often include questions about counting element occurrences in lists using HashMaps. Two approaches can solve this problem: a traditional if-else method and the getOrDefault() method. Both solutions have O(n) time and space complexity. The traditional approach works for all Java versions, while getOrDefault() requires Java 8 or higher. The getOrDefault() method provides cleaner, more concise code by eliminating if-else logic. Both methods effectively handle null inputs and empty lists, returning an empty HashMap in such cases.