Java: Addition of integers with parentheses

Question

Consider the two following lines of code:

System.out.println((1 + (1 - 1)) / 2);
System.out.println(1 + (1 - 1) / 2);

This is the output that I get:

0
1

Why is this the case? Does Java arithmetic follow PEMDAS rules?

It follows the same rules as in Math, your results were truncated because integer is the default unless otherwise stated. Not just java, pretty much every language follows the rules in Math since they are pretty much created based around Math. — Biu, Jan 18 '15 at 23:38
I was expecting 1. Malik Brahimi cleared it out for me. I guess I was just delusional and forgot integer/decimal division. — mpmp, Jan 18 '15 at 23:50

score 2 · Accepted Answer · edited Jan 18 '15 at 23:59

2

I don't see the issue, your code does follow PEMDAS. The only issue is that you're not getting 0.5 because you're using integer division. Try this:

System.out.println((1 + (1 - 1)) / 2.0);
System.out.println(1 + (1 - 1) / 2.0);

edited Jan 18 '15 at 23:59

answered Jan 18 '15 at 23:40

Malik Brahimi

Keep at it. It took me a while to figure things out too. – Malik Brahimi Jan 18 '15 at 23:49

score 1 · Answer 2 · answered Jan 18 '15 at 23:51

1

Yes, it follows the PEMDAS rule and it also truncates answers (cuts off digits after the decimal place without rounding).

answered Jan 18 '15 at 23:51

Anthony Palumbo

score 0 · Answer 3 · answered Jan 18 '15 at 23:42

0

The first one is just (1 + 0)/2 = 1/2 which gives you 0 since you are working with integers.

The second one is 1 + 0/2 = 1 + 0 = 1 which gives you 1.

answered Jan 18 '15 at 23:42

Oskar Persson

3 Answers3