Vector and null

[Sarma Lolla]

Which of the following types can be added to java.util.Vector?
A) reference
B) null
C) int
D) All of the above
The answer given in the mock are A, B.
When I verified I am able to add null to Vector.
Are there any other collection classes where I can add null?

[Thomas Paul]

All the Collection classes can hold nulls. By the way, the JavaRanch newsletter has a multi-part article on Collections.

[Jose Botella]

Sarma. Hashtable won't allow null for keys or values. While HashMap allows the null key and null values.