AtomicInteger: keep non-negative

Question

Is there a way to perform the “decrease if the result is positive or zero” using AtomicInteger ? To clarify the desired behavior:

• if the current value is greater than zero, decrement
• if the current value is zero do nothing
• (negative current value is not processed)

Answer 1

In Java 8, yes :

 atomicInteger.updateAndGet(i -> i > 0 ? i - 1 : i); 

Before Java 8, no .

Answer 2

I suppose you could do something like this pre-Java 8:

 int val = atomicInt.get(); boolean success = false; while(val > 0 && !success) { success = atomicInt.compareAndSet(val, val - 1); if(!success) { // Try again if the value is still > 0 val = atomicInt.get(); } } // Check 'success' to see if it worked 

Not the most elegant code, but I think it does the trick.