Creating a HashSet : HashSet « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. HashSet

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.