What's the difference between HashSet and Set?

Question

Saw the code snippet like

Set instances = new HashSet();

I am wondering if Hashset is a special kind of set. A

Answer 1

**

• Set:

** It is an interface which is a subtype of Collection interface, just like LIST and QUEUE.

Set has below 3 subclasses, it is used to store multiple objects without duplicates.

1. HashSet
2. LinkedHashSet
3. TreeSet(which implements SortedSet interface)

**

• HashSet:

**

Can use one NULL value(as Duplicate is not allowed), data is stored randomly as it does not maintain sequence.