Hashcode for NULL key in HashMap

collections, hashmap, java

Solution

from HashMap:

public V put(K key, V value) {
   if (key == null)
      return putForNullKey(value);
   ...

and if you look further you will see that null always goes to bin 0

Problem

I was just reading about the difference between HashMap and HashTable class in java. There I found a difference that former allow null key and later doesn't privileges for the same. As far as the working of HashMap is concern I know that, it calls hashcode method on key for finding the bucket in which that key value pair is to be placed. Here comes my question: How hashcode for a null value is computed or Is there any default value for hashcode of null key (if so please specify the value)?

Original source