ConcurrentHashMap vs Synchronized HashMap

Question

What is the difference between using the wrapper class, SynchronizedMap, on a HashMap and ConcurrentHashMap?

Is it just bein

Answer 1

Both are synchronized version of HashMap, with difference in their core functionality and their internal structure.

ConcurrentHashMap consist of internal segments which can be viewed as independent HashMaps Conceptually. All such segments can be locked by separate threads in high concurrent executions. So, multiple threads can get/put key-value pairs from ConcurrentHashMap without blocking/waiting for each other. This is implemented for higher throughput.

whereas

Collections.synchronizedMap(), we get a synchronized version of HashMap and it is accessed in blocking manner. This means if multiple threads try to access synchronizedMap at same time, they will be allowed to get/put key-value pairs one at a time in synchronized manner.