JAVA / JAVA COLLECTIONS FRAMEWORK /
HASHSET

Implements the Set interface.

Provides hash table data structure. Elements are stored randomly, and elements are accessed by their hash code. Each element has a unique hash code.

HashSet is not synchronized, after modifying by a thread, need external synchronization.

1. GENERALLY

Constructor signatures:

• (): default capacity is 16, default load factor is 0.75

• (capacity in int, load factor in float): how many elements it can store, if load factor is exceeded, the set is moved to an other set with double size

• (other Set class): converting from that set to HashSet; need identical pair types

EXAMPLE FOR CREATING AN INSTANCE OF HASHSET:

All methods of Set are available. Other methods are below.

Differences between HashSet and TreeSet:

• TreeSet stores element order, HashSet does not

• TreeSet provides navigation methods along the elements, HashSet does not

• HashSet is faster for basic operations like add, remove, contains and size than TreeMap

JUMP TO TOP

2. CONVERT TO ARRAY AND BACK

EXAMPLE FOR CONVERTING ARRAY AND BACK:

JUMP TO TOP