19_HashMap.txt

Map:

store values in key,value pair

HashMap, check HashMapDemo.java


HashTable

hashmap and hashtable diff

1) Synchronized
hashmap is non synchronized and not thread safe.

hash table is synchronized and thread safe

2) Null values

hashmap allows one null key and many null values...whereas hashtable does not allow null values or keys

3)iterating:

hashmap uses iterator to iterate through it whereas hashtable uses enumerator to iterate through it. other than hashtable only vector has enumerator iterataing concept.