When do I need to use AtomicBoolean in Java?

How I can use AtomicBoolean and what is that class for?

When multiple threads need to check and change the boolean. For example:

if (!initialized) {
   initialize();
   initialized = true;
}

This is not thread-safe. You can fix it by using AtomicBoolean:

if (atomicInitialized.compareAndSet(false, true)) {
    initialize();
}

Here is the notes (from Brian Goetz book) I made, that might be of help to you

AtomicXXX classes

provide Non-blocking Compare-And-Swap implementation
Takes advantage of the support provide by hardware (the CMPXCHG instruction on Intel) When lots of threads are running through your code that uses these atomic concurrency API, they will scale much better than code which uses Object level monitors/synchronization. Since, Java's synchronization mechanisms makes code wait, when there are lots of threads running through your critical sections, a substantial amount of CPU time is spent in managing the synchronization mechanism itself (waiting, notifying, etc). Since the new API uses hardware level constructs (atomic variables) and wait and lock free algorithms to implement thread-safety, a lot more of CPU time is spent "doing stuff" rather than in managing synchronization.
not only offer better throughput, but they also provide greater resistance to liveness problems such as deadlock and priority inversion.

There are two main reasons why you can use an atomic boolean. First it's mutable, you can pass it in as a reference and change the value that is associated to the boolean itself, for example.

public final class MyThreadSafeClass{

    private AtomicBoolean myBoolean = new AtomicBoolean(false);
    private SomeThreadSafeObject someObject = new SomeThreadSafeObject();

    public boolean doSomething(){
         someObject.doSomeWork(myBoolean);
         return myBoolean.get(); //will return true
    }
}

and in the someObject class

public final class SomeThreadSafeObject{
    public void doSomeWork(AtomicBoolean b){
        b.set(true);
    }
}

More importantly though, it's thread safe and can indicate to developers maintaining the class, that this variable is expected to be modified and read from multiple threads. If you do not use an AtomicBoolean, you must synchronize the boolean variable you are using by declaring it volatile or synchronizing around the read and write of the field.

When do I need to use AtomicBoolean in Java?

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