HashMap with multiple values under the same key

Question

Is it possible for us to implement a HashMap with one key and two values. Just as HashMap?

Please do help me, also by telling (if there is no way) any other way to

Answer 1

No, not just as a HashMap. You'd basically need a HashMap from a key to a collection of values.

If you're happy to use external libraries, Guava has exactly this concept in Multimap with implementations such as ArrayListMultimap and HashMultimap.