Android calculations are returning whole numbers when it shouldn't

Question

So I'm making a little app for myself and everything has been fine until now, I have no idea what I could have done but my answers are all coming out as whole numbers when I need decimal answers.

the code:

public float NumberCalc(){
    float number1 = 255/100;
    float number2 = ((5/366)*100);
    float finalNumber =(number1*number2);
    return finalNumber;
}

So I get 2.0 for number1 & 0.0 for number2 and I'm stumped

Can anyone shed some light on this scenario?

not `Android calculations` but rather `java calculations` – ılǝ Oct 31 '13 at 00:57 — ılǝ, Oct 31 '13 at 00:57

score 4 · Answer 1 · edited Oct 31 '13 at 00:55

4

You are performing integer division and storing the result as floats.

255/100 results in 2 integer, saved as a float 2.0 To avoid this you can either specify the division as float by integer or integer by float division 255.0/100 or 255/100.0 or 255f. The same applies to number2

edited Oct 31 '13 at 00:55

Geobits

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answered Oct 31 '13 at 00:54

arynaq

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Haha I'm so sleepy I didn't see my mistake! Cheers! – Russell Cargill Oct 31 '13 at 00:59

score 1 · Accepted Answer · answered Oct 31 '13 at 00:57

The numbers 255 and 100 in your first division are both int. So when you divide two ints in java you get the 'quotient'. Java then casts this answer to float.

You can instead cast your numerator to float before the division occurs to guarantee the result will be a float division.

Try:

public float NumberCalc(){
    float number1 = (float) 255/100;
    float number2 = (((float)5/366)*100);
    float finalNumber =(number1*number2);
    return finalNumber;
}

score 0 · Answer 3 · answered Oct 31 '13 at 00:54

0

cast your fractions to a float or make variables set to (for example)

float a = 200f

for your math. You don't need to make variables it just makes it neater in my opinion. Android calculates division into integers.

answered Oct 31 '13 at 00:54

zgc7009

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Android calculations are returning whole numbers when it shouldn't

3 Answers3