title: Does AtomicBoolean really achieve atomicity?
body: <p>I understand valid use cases for AtomicInteger but I am confused on how can AtomicBoolean, guarantee atomicity of two actions i. 'changing the boolean-value' and ii. execute the 'one-time-logic'  eg initialize() in following often-quoted use-case for AtomicBoolean variable atomicInitialized:</p>
  
  <pre><code>if (atomicInitialized.compareAndSet(false, true)) {
      initialize();
  }
  </code></pre>
  
  <p>This operation will first set the atomicInitialized to true(if it is false) and then execute intialize() which isn't safe. It will guarantee that initialize() is only called once, but the second thread to hit the getAndSet() will not be delayed until the first thread has finished the initialisation. So, the AtomicBoolean while providing atomicity in updating boolean value doesn't really provide atomicity for entire 'if-block' and synchronize/lock mechanism has to be used for achieving complete atomicity. Hence, above often quoted, popular use-case, isn't really atomic!!</p>