What is the difference between synchronized and volatile in Java?

Can you explain the difference between synchronized and volatile in Java?

Sure! In Java, 'synchronized' is used to control access to a block of code or an object by multiple threads, ensuring that only one thread can execute it at a time. 'Volatile', on the other hand, is a keyword that indicates that a variable's value will be modified by different threads, ensuring that changes made by one thread are visible to others.

When should I use synchronized instead of volatile?

You should use 'synchronized' when you need to ensure that only one thread can access a block of code at a time, especially when that code modifies shared data. Use 'volatile' when you want to ensure visibility of changes to a variable across threads without locking.

Can you give an example of when to use each?

Certainly! Use 'synchronized' when updating a shared counter to prevent race conditions. Use 'volatile' for a flag variable that indicates whether a thread should keep running, as it only needs visibility, not atomicity.

Are there performance implications for using synchronized?

Yes, using 'synchronized' can lead to performance overhead due to thread contention and context switching. It's generally slower than using 'volatile', which has less overhead but doesn't provide atomicity.