Java programming, decimals numbers

Question

This is a compound interest calculator, everything works fine excepts that i can't figured how to get my answer to have just 2 decimals, not a long number as right now. Please take a look at the codes and suggest if anything i should correct. Thank you very much.

class InvestmentProject{
public double CompoundInterest(double InitialDeposit, double YearlyContribution, double InterestRate, int PeriodsInYr) {

double RateInDecimal = InterestRate/100;
double Value = YearlyContribution/RateInDecimal - YearlyContribution/(RateInDecimal * Math.pow(1 + RateInDecimal, PeriodsInYr));
return (InitialDeposit + Value) * Math.pow(1 + RateInDecimal, PeriodsInYr);
}
}

score 1 · Answer 1 · answered Nov 14 '12 at 22:17

1

You should never use floats or doubles when doing financial calculations, and particularly comparisons, in Java. use BigDecimal instead. Here is an article that explains why.

answered Nov 14 '12 at 22:17

Paul Sanwald

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score 0 · Answer 2 · edited May 23 '17 at 12:12

0

Use Math.round(result*100)/100;

There's a similar question here ( How to round a number to n decimal places in Java ) that outlines more ways of doing rounding in Java.

edited May 23 '17 at 12:12

Community

1
1

answered Nov 14 '12 at 22:06

Krease

15,805
8
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score 0 · Answer 3 · edited Nov 14 '12 at 23:22

You should use the decimalFormat Class

import java.text.DecimalFormat;  

public class Java0605
{
    public static void main (String args[])
    {
        DecimalFormat output = new DecimalFormat("00000");
        System.out.println(output.format(1));
        System.out.println(output.format(12));
        System.out.println(output.format(123));
        System.out.println(output.format(1234));
        System.out.println(output.format(12345));
        System.out.println(output.format(123456));
        System.out.println(output.format(1234567));
        System.out.println();
    }
}

Java programming, decimals numbers

3 Answers3