What is the difference between ConcurrentHashMap and HashMap?

What is the difference between ConcurrentHashMap and HashMap?

ConcurrentHashMap is designed for concurrent access, allowing multiple threads to read and write without locking the entire map, while HashMap is not thread-safe.

Can you explain how ConcurrentHashMap achieves thread safety?

ConcurrentHashMap uses a technique called lock striping, which divides the map into segments, allowing multiple threads to operate on different segments simultaneously.

Are there any performance differences between the two?

Yes, ConcurrentHashMap generally performs better in multi-threaded environments due to its non-blocking reads and segmented locking.

When should I use ConcurrentHashMap instead of HashMap?

You should use ConcurrentHashMap when you expect multiple threads to access the map concurrently, to avoid data inconsistency.