EPAM Systems Interview Question

What if we insert with key null to a HashMap?

Interview Answers

Anonymous

May 4, 2019

Didn't know, however, it's a very edge case, you can insert and the hashcode will be 0, so it's identifying the '0' bucket.

Anonymous

Sep 1, 2020

HashMap allows null as both key and value, as well. So you can associate a value to null key. However, TreeMap throws a NullPointerException if you try to put a key with null value.