Why ConcurrentHashMap.putifAbsent is safe?

I have been reading for concurency since yesterday and i dont know much things... However some things are starting to getting clear...
I understand why double check locking isnt safe (i wonder what is the propability the rare condition to occur) but volatile fixes the issue in 1.5 +....
But i wonder if this occurs with putifAbsent

like...

myObj = new myObject("CodeMonkey");
cHashM.putIfAbsent("keyy",myObj);  

Then does this ensures that myObj would be 100% intialiased when another thread does a cHashM.get() ??? Because it could have a reference isnt completely initialised (the double check lock problem)