Why do I keep getting zero in my equation?

Question

I am trying to do some simple percents, and My results always is zero.

String taste = jsonArray.getJSONObject(i).getString("taste");
                String rate = jsonArray.getJSONObject(i).getString("rate");

                Log.d("taste", rate);
                int rateNum = Integer.parseInt(rate);

                Log.d("taste", "rateNum is " + rateNum);

                int percent = rateNum / count;

                percent = percent * 100;

                Log.d("taste", "percent is " + percent);

The odd part is looking at my Log my rateNum and count Variables are both numbers and not zero:

06-26 21:52:44.319: D/taste(11812): count it:20
06-26 21:52:44.319: D/taste(11812): 13
06-26 21:52:44.319: D/taste(11812): rateNum is 13
06-26 21:52:44.319: D/taste(11812): percent is 0
06-26 21:52:44.319: D/taste(11812): 3
06-26 21:52:44.319: D/taste(11812): rateNum is 3
06-26 21:52:44.319: D/taste(11812): percent is 0
06-26 21:52:44.319: D/taste(11812): 3
06-26 21:52:44.319: D/taste(11812): rateNum is 3
06-26 21:52:44.319: D/taste(11812): percent is 0
06-26 21:52:44.319: D/taste(11812): 1
06-26 21:52:44.319: D/taste(11812): rateNum is 1
06-26 21:52:44.319: D/taste(11812): percent is 0

So I have no idea why I keep getting zero as my percent.

Answer 1

You are suffering from mistakes with numerical type.

When you get rateNum, it is an int , as is count. Since int/int=int(truncating decimals), you are multiplying 0 by 100 to get 0.

The solution is as follows:

String taste = jsonArray.getJSONObject(i).getString("taste");
            String rate = jsonArray.getJSONObject(i).getString("rate");

            Log.d("taste", rate);
            double rateNum = Double.parseInt(rate);

            Log.d("taste", "rateNum is " + rateNum);

            double percent = rateNum / count;

            percent = percent * 100;

            Log.d("taste", "percent is " + percent);

Answer 2

You might want to try

int percent = (100*rateNum) / count;

or use floating point for the math. Your value is being rounded down to zero and then never recovering.

Answer 3

You are using int type to save the percent, so a number like 0.8 will be rounded to 0 at int percent = rateNum / count;

Use this instead

float percent = rateNum / count;