Android get calculation result with decimal

Question

I'm making some calculations on my project in order to see how many trucks could be parked on a road of X meters.

I have this:

    int road1 = 140;
    double trucks = 0;
    
    trucks = (road1-10)/20;
System.out.println("trucks"+trucks);

The problem is that if you calculate by yourself, the result will be 6.5. So you could park 6.5 trucks.

But I always get 6.0

score 4 · Accepted Answer · answered Sep 15 '21 at 14:28

4

You are doing the calculation with ints, if you change to trucks = (road1-10)/20.0 you will get the answer 6.5

answered Sep 15 '21 at 14:28

Per.J

The expression will be evaluated _first_ & then cast to double only at assignment, but by that stage you've already lost (truncated) the decimal places. – anotherdave Sep 15 '21 at 14:31
Thanks, I still can't mark as solved so I will do it in 6'. – Giovanni Sep 15 '21 at 14:33
What if I get 6.8 and I want to round to 6.5? – Giovanni Sep 15 '21 at 14:33
Round to nearest half is answered here: https://stackoverflow.com/questions/23449662/java-round-to-nearest-5 – Per.J Sep 15 '21 at 14:37
Thanks @Per.J but I want to round down, the linked solution is rounding up – Giovanni Sep 15 '21 at 14:44
@Giovanni replace `Math.round` with `Math.floor` – anotherdave Sep 15 '21 at 15:20

1 Answers1