Difference between synchronized and volatile in Java multithreading

In Java multithreading, the main difference between synchronized and volatile is how they ensure visibility and atomicity.

Synchronized:

When a block of code is synchronized, only one thread can access it at a time, ensuring mutual exclusion. This prevents race conditions and ensures thread safety. Synchronized blocks also ensure memory consistency, as changes made by one thread are visible to other threads when they acquire the lock.

Volatile:

On the other hand, using the volatile keyword in Java ensures that changes made to a variable are immediately visible to other threads. However, it does not provide atomicity like synchronized blocks. Volatile variables are used when only visibility is required, not atomicity.

It's important to note that synchronized and volatile are not interchangeable in Java multithreading, as they serve different purposes and have different implications on thread safety and memory consistency.

Understanding the difference between synchronized and volatile is crucial for writing efficient and thread-safe Java multithreading programs.