AtomicInteger and Math.max

Question

I was trying to get the maximum value of a calculatedValue in a cycle and I wanted it to be thread safe. So I decided to use AtomicInteger and Math.max, but I can't find a solution so that the operation can be considered atomic.

AtomicInteger value = new AtomicInteger(0);


// Having some cycle here... {
    Integer anotherCalculatedValue = ...;
    value.set(Math.max(value.get(), anotherCalculatedValue));
}

return value.get()

The problem with that is that I make two operations, therefore is not threadsafe. How can I solve this? The only way is to use synchronized ?

Answer 1

If Java 8 is available you can use:

AtomicInteger value = new AtomicInteger(0);
Integer anotherCalculatedValue = ...;
value.getAndAccumulate(anotherCalculatedValue, Math::max);

Which from the specification will:

Atomically updates the current value with the results of applying the given function to the current and given values, returning the previous value.