List Set Map, listsetmap
List sets are all interfaces and all inherit the Collection interface.
ArrayList LinkList directly implements the List Interface
HashSet implements the Set interface TreeSet inherited from the parent class AbstractSet and indirectly implemented the Set interface Map is the interface, the Collection interface HashMap is not implemented. The Map Interface Collection class ArrayList collections list HashSet TreeSet Vector HashMap Hashtable1.HashMap inheritance is AbstractMap class Hashtable inheritance is Dictionary Class 2. hashMap is thread-safe, non-synchronous, and more efficient than Hashtable is thread-safe, synchronous 3. hashMap allows null to be used as the key or value of an entry. Hashtable cannot directly throw NullPointerExceptionConcurrentHashMap and inherits the same parent class as HashMap, but the thread is secure,
