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

A synchronized method/block blocks all access to that method/block from other threads while one thread is performing the method.

An Atomic... can be accessed by many threads at once - there are usually CAS access methods available for them to help with high-speed access.

As such - they are completely different but they can sometimes be used to solve parallel accessibility issues.

These two classes use the two different methods to return a steadily increasing number such that the same number will never be delivered twice. The AtomicInteger version will run faster in a high-load environment. The one using synchronized will work in Java 4 and older.

public class Incremental1 {

    private AtomicInteger n = new AtomicInteger();

    public Integer nextNumber() {
        // Use the Atomic CAS function to increment the number.
        return n.getAndIncrement();
    }
}

public class Incremental2 {

    private int n = 0;

    public synchronized Integer nextNumber() {
        // No two threads can get in here at the same time.
        return n++;
    }

}