How is hashmap different from hashtable

Question

I cannot differentiate between the two terminologies Hashmap and Hashtable.

Answer 1

Here are few differences between HashMap and HashTable:

• HashMap is non synchronized whereas HashTable is synchronized.
• HashMap is fast whereas HashTable is slow
• HashMap allows one null key and multiple null values whereas HashTable doesn't allow any null value or key.
• HashMap inherits AbstractMap class whereas HashTable inherits Dictionary class.
• HashMap is traversed by Iterator whereas HashTable is traversed by Enumerator and Iterator.

Answer 2

HashMap and HashTable:

1) Hashtable and Hashmap implement the java.util.Map interface

2) Both Hashmap and Hashtable is the hash-based collection. and working on hashing. so these are similarity of HashMap and HashTable.

• What is the difference between HashMap and HashTable?

1) The first difference is HashMap is not thread safe While HashTable is ThreadSafe
2) HashMap is performance wise better because it is not thread safe. while Hashtable performance wise is not better because it is thread safe. so multiple thread cannot access Hashtable at the same time.