[Java] Difference between Hashmap and HashTable
- Difference in inheritance
HashMap
HashTable
HashTable extends Dictionary
The HashTable parent class dictionary is no longer used here.
- Difference between null keys Null key and null value cannot be used in HashTable.
It can be used with HashMap.
- Difference in multi-thread support
All IFs in HashTable have been added synchronized, so they can operate in a multi-threaded environment as they are.
HashMap can cause a deadlock when used in multiple threads. *: To avoid this, ConcurrentHashMap was added from java1.5, multithreading Can be used in the environment.
4, difference in speed HashMap is fast HashTable is slow
Summary In general, you should use HashMap, but for multithreading, use ConcurrentHashMap.
https://github.com/YanHengGo/java/tree/master/03_hashmap
Recommended Posts