Math.round does not round off numbers

Question

Good Evening,

My code won't round off, and I don't know why! Please help!

import java.util.*;
import java.math.*;

public class Arithmetic {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        int tipPercentage;  // tip percentage
        int taxPercentage;  // tax percentage
        int totalTip;       // total tip
        int totalTax;       // total tax
        double mealCost;    // original meal price
        double totalCost = 0.0; // total meal price

        // Write your calculation code here.
            mealCost = scan.nextDouble();
            tipPercentage = scan.nextInt ();
            taxPercentage = scan.nextInt();

            totalCost += mealCost;
            totalCost += mealCost*tipPercentage/100;
            totalCost += mealCost*taxPercentage/100;


        // cast the result of the rounding operation to an int and save it as totalCost 
            mealCost=(int)Math.round(totalCost);


        // Print your result
        System.out.println (" The total meal cost is " + totalCost + " dollars. ");
    }
}

Your question is a little vague, could you please edit it with a bit more detail on what the problem is — Barney Chambers, Aug 03 '17 at 00:23
You have a typo, but the whole approach is fallacious. See my answer in the duplicate for why. If you want decimal places you must use a decimal radix, e.g. via `BigDecimal` or `DecimalFormat`, and in any case you should use `BigDecimal` for money, not floating-point. — user207421, Aug 03 '17 at 00:40

score 0 · Answer 1 · answered Aug 03 '17 at 00:27

0

You are appending totalCost to your printed string, when you are assigning a rounded value to mealCost. In other words,

mealCost=(int)Math.round(totalCost);

should become

totalCost=(int)Math.round(totalCost);

Additionally, you may want to add prompts before taking in input as well as perhaps reconsidering your rounding, unless you really want it to the nearest dollar.

answered Aug 03 '17 at 00:27

CassOnMars

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So this actually worked as it shows my total changing from 15.36, to 15.0... Is there a way to remove the .0 portion from the final result? – Victor Lombardo Aug 03 '17 at 00:41
If you want to get rid of the .0 , then just cast mealCost as an int in your print statement. – Luke Thistlethwaite Aug 03 '17 at 00:45

score -1 · Accepted Answer · answered Aug 03 '17 at 00:32

-1

mealCost is the variable that you are trying to round, whereas totalCost is the variable that you print out and display to the user.

System.out.println (" The total meal cost is " + totalCost + " dollars. ");

Also, when displaying cost it might be a good idea to round to the nearest hundredth. You can do this by saying something like

mealCost=Math.round(totalCost*100)/100.0

Finally, you should prompt the user, so they know what they are inputting in the console.

answered Aug 03 '17 at 00:32

Luke Thistlethwaite

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Thank you so much! that makes a lot of sense. – Victor Lombardo Aug 03 '17 at 00:43
Of course, in the examples above, you probably want to change mealCost to totalCost... I was just unsure of which one you wanted to print out. – Luke Thistlethwaite Aug 03 '17 at 00:44
you should use BigDecimal for money, not floating-point. – Scary Wombat Aug 03 '17 at 01:47

Math.round does not round off numbers

2 Answers2