Following are some difference as :
| HashMap | HashTable |
| 1 Hashmap is not synchronized in nature . |
1 Hashtable is synchronised. |
| 2 iterator in the HashMap is fail-safe . Fail-safe - “if the Hashtable is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove method, the iterator will throw a ConcurrentModificationException” |
2 while for the Hashtable is not. |
| 3 HashMap permits null values and only one null key. |
3 while Hashtable doesn't allow key or value as null. |
| 4 HashMap use iterator. |
4 Hashtable use enumeration. |
| 5 HashMap is faster. | 5 Hashtable is slower. |