How does ConcurrentHashMap differ from Hashtable?

What are the main differences between ConcurrentHashMap and Hashtable?

ConcurrentHashMap is designed for concurrent access, allowing multiple threads to read and write without locking the entire map, while Hashtable locks the entire map for each operation.

Which one is more efficient in a multi-threaded environment?

ConcurrentHashMap is generally more efficient in multi-threaded environments due to its finer-grained locking mechanism.

Are there any scenarios where I should prefer Hashtable?

Hashtable is considered legacy and should be avoided in new applications, but it may be used in older systems where compatibility is needed.

Can you give an example of how to use ConcurrentHashMap?

Sure! Here's a simple example: ConcurrentHashMap<String, Integer> map = new ConcurrentHashMap<>(); map.put("key1", 1); This allows safe concurrent access.