How do HashMap and ConcurrentHashMap differ in Java?

What are the main differences between HashMap and ConcurrentHashMap in Java?

HashMap is not thread-safe, while ConcurrentHashMap is designed for concurrent access, allowing multiple threads to read and write.

Can you explain how ConcurrentHashMap achieves thread safety?

ConcurrentHashMap uses a technique called segmentation, which divides the map into segments, allowing concurrent access to different segments.

Are there any performance differences when using these two maps?

Yes, ConcurrentHashMap generally performs better in multi-threaded environments due to its ability to allow concurrent reads and writes.

When should I use HashMap instead of ConcurrentHashMap?

Use HashMap when you don't need thread safety and want better performance in single-threaded scenarios.