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javahashmaphashtable

ConcurrentHashMap and Hashtable in Java

What is the difference between a ConcurrentHashMap and a Hashtable in Java?

Which is more efficient for threaded applications?

Solution

  • ConcurrentHashMap uses multiple buckets to store data. This avoids read locks and greatly improves performance over a HashTable. Both are thread safe, but there are obvious performance wins with ConcurrentHashMap.

    When you read from a ConcurrentHashMap using get(), there are no locks, contrary to the HashTable for which all operations are simply synchronized. HashTable was released in old versions of Java whereas ConcurrentHashMap is a java 5+ thing.

    HashMap is the best thing to use in a single threaded application.