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Some time ago I started to investigate java.util.concurrent package. And my question is about AtomicStampedReference class. The class has method 

public V get(int[] stampHolder) {
    ...
}

which gets reference and stamp atomically (please, correct me if I'm wrong).

Is there some special reasons why parameter for the method is array? Documentation says nothing about it.

Dmitriy Protsenko
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1 Answers1

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Maybe (probably) it is just a hack to simulate out parameters, since in this case two values should be returned: V and an int value.

Another possibility would be to return a tuple Tuple<V,Integer>, but Java has no Tuple class, and it would maybe be less efficient to create an instance of a Tuple object and additionally boxing the int, which may be important in the context of concurrency.

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user140547
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  • It is clear that actually we get two fresh values. But why did mr. Doug Lea decide to use `int[] stampHolder` instead of using `int stampHolder` for example? This method uses only the first array element - `stampHolder[0] = p.integer`. – Dmitriy Protsenko Sep 30 '16 at 07:42
  • @DmitriyProtsenko: Well if the method was defined as `public V get(int stampHolder)` if `stampHolder` is modified the caller won't get the updated value since it is passed by value. see http://stackoverflow.com/questions/40480/is-java-pass-by-reference-or-pass-by-value – user140547 Sep 30 '16 at 08:30
  • The last link is very useful. Now I don't have any questions. Thanks! – Dmitriy Protsenko Sep 30 '16 at 09:12