Why am I getting 0?

Question

I keep getting 0 with the following equation, and I'm sure it is something I am missing, but this has been bugging me for the past few days.

int BASE_SIZE = 8;
Point screenSize = new Point(1440,2000);

mMaxSize = mScreenSize.x/BASE_SIZE;

// This line is the line causing issue.
int surfaceViewSize = mMaxSize * ((BASE_SIZE-1)/BASE_SIZE);

This is regardless of if I make the variable an integer, if I use Math.round, I make it a double, anything. I can not for the life of me figure this out.

There's a method that can already get you the screen size, by the way — OneCricketeer, Aug 01 '17 at 13:57
`(BASE_SIZE-1)/BASE_SIZE` is zero because Java uses integer division. Maybe you mean `mMaxSize * (BASE_SIZE-1) / BASE_SIZE;` — khelwood, Aug 01 '17 at 13:57
yes I use that method to get the screen size, I just didn't feel like inputting that in as this is not in an activity. And the goal here is to get mMaxScreenSize .x * 7/8. Hence the mMaxScreenSize.x * ((8-1)/8) — miversen33, Aug 01 '17 at 14:00
whoever tagged this, thank you! I knew it was an issue with integer division but couldn't figure how to resolve it. Casting to a double corrected the issue. — miversen33, Aug 01 '17 at 14:07

score 3 · Accepted Answer · edited Aug 01 '17 at 13:57

3

this integer division here:

(BASE_SIZE-1)/BASE_SIZE

result to be

int surfaceViewSize = mMaxSize * 0;

you need to cast one of the operands into a double or float

replace your operations with:

mMaxSize = 1.0*mScreenSize.x/BASE_SIZE;
int surfaceViewSize = mMaxSize * ((1.0*BASE_SIZE-1)/BASE_SIZE);

edited Aug 01 '17 at 13:57

xenteros

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answered Aug 01 '17 at 13:55

ΦXocę 웃 Пepeúpa ツ

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*"you need to **cast** one of the operands into a double or float"* and then you proceed without casting *anything*, instead multiplying by the double number 1, and lack of cast making the code not even compile. – Andreas Aug 01 '17 at 14:01

score 2 · Answer 2 · edited Aug 01 '17 at 13:58

2

int surfaceViewSize = (mMaxSize * (BASE_SIZE-1))/BASE_SIZE;

Try this its just a braces issue

edited Aug 01 '17 at 13:58

xenteros

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answered Aug 01 '17 at 13:57

PRADEEP Kumar

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No, it's not. It's all about integer division – xenteros Aug 01 '17 at 13:59
To be fair, changing the braces will change the way the integer division is done but in the end xenteros is right: the basic problem is integer division. – Thomas Aug 01 '17 at 14:00
You don't actually need the outer parentheses at all. But yes, this is the best answer. There's no point in converting everything to `float` or `double` when you're going to assign the result back to an `int` anyway. You just have to be smart about the order you do things. – Dawood ibn Kareem Aug 01 '17 at 14:03

Why am I getting 0?

2 Answers2