HashSet class

Hierarchy of HashSet class:

 

 public class HashSet<E>

        extends AbstractSet<E>
           implements Set<E>, Cloneable, java.io.Serializable

Key points:

• HashSet is sub class of AbstractSet class.
• Underlying data structure of HashSet is HashTable.
• HashSet implements Serializable and Cloneable interfaces
• HashSet does not allow duplicate elements.
• Insertion order is not preserved. No order(Based on hashcode of objects)

Constructors of HashSet:

1.HashSet( )

• Creates an empty HashSet object with default initial capacity 16.  Fill ratio or load factor 0.75

2.HashSet(Collection obj)

• This constructor initializes the hash set by using the elements of the collection obj.

3.HashSet(int capacity)

• Creates an empty HashSet object with given capacity.

4.HashSet(int capacity, float fillRatio)

• This constructor initializes both the capacity and the fill ratio (also called load capacity) of the hash set from its arguments (fill ratio 0.1 to 1.0)