HashMap vs Hashtable

 

Hashmap vs Hashtable 

• HashMap is non-synchronized. It is not thread-safe and can’t be shared between many threads without proper synchronization code whereas Hashtable is synchronized. It is thread-safe and can be shared with many threads.
• HashMap allows one null key and multiple null values whereas Hashtable doesn’t allow any null key or value.
• HashMap is generally preferred over HashTable if thread synchronization is not needed.

Ref: 

• https://www.geeksforgeeks.org/differences-between-hashmap-and-hashtable-in-java/
• https://www.javatpoint.com/java-map
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