The HashSet class provides four constructors broken into two sets. The first three constructors
create empty sets of varying sizes:
public HashSet()
public HashSet(int initialCapacity)
public HashSet(int initialCapacity, int loadFactor)
When creating any collection, it is always best to have the local variable be of the interface type,
Set set = new HashSet().
For easier to change the set to a TreeSet or some other set implementation.
The fourth constructor acts as a copy constructor.
public HashSet(Collection col)
If the original collection had duplicates, only one of the duplicates will be in the final created set.