Question

I was recently debugging a problem where a result was much larger than expected. What I had intended to write was:

y += height + rowHeight * 2;

What I had written was

y += height * + rowHeight * 2;

I didn’t see the error right away because, apparently * + is a valid operator in Java, or at least Android java. I’ve never heard anything about this before, and I have no idea what it means.

As an experiment, I found that the generalized form of this is, as a regex [*/%][+-]*

It looks like some form of polish notation, but I was unaware that Java supported such.

So… where would I find documentation about this operator, and what, exactly, does it mean?

Answer 1

It’s using the unary plus operator – so it’s like this:

y += height * (+rowHeight) * 2;

To give an example which wouldn’t look odd at all, but using unary minus instead of unary plus:

y += height * -rowHeight * 2;

Hopefully that makes more sense 🙂