Which is the difference between AtomicReference and Synchronized?

Question

Is there any difference between AtomicReference and Synchronized?
E.G.

public class Internet {
    AtomicReference address;
    public String g         


        

Answer 1

There's nothing wrong with the other answers here if you can understand them, but they mostly seem to focus on details, nomenclature, and use-cases, while skipping over the big picture that "everybody" already knows.

Here's the big picture---the difference between an AtomicFoobar operation and a synchronized block.

An AtomicFoobar operation (e.g., atomicReference.compareAndSet(...)) either performs exactly one, very simple, thread-safe operation, or else it fails. Regardless of whether it succeeeds or fails, it will never make the thread wait.

A synchronized block, on the other hand is as complicated as you make it---there is no limit to how many statements are executed while the lock is locked. A synchronized block will never fail, but it may make the calling thread wait until the operation(s) can be safely performed.

On most architectures, each AtomicFoobar methods is implemented as a Java native method (i.e., C code) that executes a single, specialized hardware instruction. Synchronized, on the other hand is most always implemented with operating system calls which, somewhere deep in the guts, probably make use of the same hardware instructions.