what must be hashcode of null objects in Java?

Question

According to a comment from this post, hascode of null objects can throw NPE or a value of zero. This is implementation speci

Answer 1

If you will search around, you'll notice that HashMap has a special handling for null keys. null values are fine as you don't compute hash code for them in a HashMap. This is the reason why null keys work fine in HashMap. As to why Objects.hashCode works fine, take a look at Rohit's answer.