How to resolve a Java Rounding Double issue [dupli

Question

This question already has an answer here:

• Retain precision with double in Java 20 answers

Seems like the subtraction is triggering some kind of issue and the resulting value is wrong.

double tempCommission = targetPremium.doubleValue()*rate.doubleValue()/100d;

78.75 = 787.5 * 10.0/100d

double netToCompany = targetPremium.doubleValue() - tempCommission;

708.75 = 787.5 - 78.75

double dCommission = request.getPremium().doubleValue() - netToCompany;

877.8499999999999 = 1586.6 - 708.75

The resulting expected value would be 877.85.

What should be done to ensure the correct calculation?

Answer 1

Any time you do calculations with doubles, this can happen. This code would give you 877.85:

double answer = Math.round(dCommission * 100000) / 100000.0;