Question

Why doesn’t this work?

private List<Integer> xShot = new ArrayList<Integer>();
     ...codes
     ...codes
     ...codes
     ...codes
     xShot.get(0) += 5;

Can’t understand why the left-hand side of an assignment´isn’t is a variable..

Someone help?

Answer 1

If you just want to increment by 5 and aren’t limited to List<Integer> specifically, you could avoid arguably verbose xShot.set(0, xShot.get(0) + 5) and do this instead:

List<AtomicInteger> xShot = new ArrayList<AtomicInteger>();
xShot.get(0).addAndGet(5);

This will increment the value of the AtomicInteger in xShot.get(0) by 5 in-place without further ado.