How to prevent number being rounded to 0, Android Studio

Question

    public int total;
    public int likes;
    public double average;

    total = 5;
    likes = 21;

    average = likes / total;

    Log.d("Average", average);

Hi, average = likes / total should return 4.2, however, its running 4.0. How can I keep it as 4.2 and not 4.0?

Cast one of the variables as a double, otherwise it rounds down because integers are rounded. — AntonH, Jan 26 '17 at 17:58
Do you mean change total or likes to double? if so, I have tried that and it still returns 4.0 — Josh Joe, Jan 26 '17 at 17:58

score 2 · Answer 1 · answered Jan 26 '17 at 18:02

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average = (double)likes / total;

answered Jan 26 '17 at 18:02

Anurag Aggarwal

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upvoted for shortness, but I fear someone could think that's a magic constant. – CoffeDeveloper Jan 26 '17 at 18:14
haha , right @DarioOO . Thanks for the vote though! – Anurag Aggarwal Jan 26 '17 at 18:18
welcome :) @JoshJoe – Anurag Aggarwal Jan 26 '17 at 18:19
AntonH asnwered it first so I had to accept his :) I did vote yours up but because I am under 15 rep it wont show – Josh Joe Jan 26 '17 at 18:21
@JoshJoe I answered first :) anyway no worries !! – Anurag Aggarwal Jan 26 '17 at 18:23
he beat you to it in the comment answer :) – Josh Joe Jan 26 '17 at 18:24
oh ! I just looked at the comment section :) – Anurag Aggarwal Jan 26 '17 at 18:26
Is it possible to do this with a float? or should I convert double to float because I just found out I need the number to be a float – Josh Joe Jan 26 '17 at 18:39
you can use float also , float average = (float)likes / total; – Anurag Aggarwal Jan 26 '17 at 18:40
Simple and accurate answer.. :) – Devraj Feb 06 '17 at 16:36

score 2 · Accepted Answer · edited Jan 26 '17 at 18:15

2

Calculations using only integers causes the end result to be integer, even if later you assign it to a floating point value like double. Integer division works by counting how many times the denominator can fit entirely in the numerator.

To resolve, you have to cast at least one of the 2 operands in the division so that the division is performed already in double precision (numbers inside arithmetic operations are automatically casted to a type that allow greater precision than its operands, if at least one of the operands have that precision):

average = (double)likes / total;

or

average = likes / (double) total;

Please note that this is different than average = (double) (likes / total);, which would cast the result after it has already been rounded down.

edited Jan 26 '17 at 18:15

CoffeDeveloper

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answered Jan 26 '17 at 18:06

AntonH

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Thanks for the headup with the space in (double) :( I made that mistake – Josh Joe Jan 26 '17 at 18:15
Is it possible to do this with a float? or should I convert double to float because I just found out I need the number to be a float – Josh Joe Jan 26 '17 at 18:37
Possible also with `float`, yes. – AntonH Jan 26 '17 at 18:44
Can you show me please I tried doing this (float) instead of (double) but it underlines in red – Josh Joe Jan 26 '17 at 18:47
I want to get the value 4.2 but it rounding up if I convert double to float it gives 5 – Josh Joe Jan 26 '17 at 18:57
@JoshJoe Are you changing both the type of the variable `average` as well as the cast to `float`? – AntonH Jan 26 '17 at 19:02
Yes, I only want the float for average – Josh Joe Jan 26 '17 at 19:17
I took your code and changed `double` to `float` (`float average;` and `average = (float) likes / total;`) and it displays `4.2`. Did you change anything else? – AntonH Jan 26 '17 at 19:21
Sorry, I wrote name of wrong variable. works now thanks. – Josh Joe Jan 26 '17 at 19:29
upvooted for "Calculations using only integers causes the end result to be integer, even if later you assign it to a floating point value like double" – Ravi Vaniya Dec 17 '21 at 12:39

How to prevent number being rounded to 0, Android Studio

2 Answers2