Removing to 2 decimal places-CodePudding

I am writing a function in which it should return the total amount that has been rounded to the nearest up pound (£). Note: the inputs are written as whole numbers without decimal places so 260 is actually £2.60 etc.

E.g.

intput: 260 -> output: 0.40

intput: 520 -> output: 0.80

total = 1.20 (because 40p 80p)

I have written out this function:

public Double nearestPoundTotaler(List<Integer> transactions)
{
    double total = 0.00;

    for(Integer amount : transactions)
    {
        int penceAmount = amount % 100;
        int penceToNearestNextPound = 100 - penceAmount;
        double answer = penceToNearestNextPound / 100.0;
        total = total   answer;
    }
    return total;
}

I have written unit tests and the logic works but the test fails since the decimal places are incorrect. E.g. if passing 260,260,260 into the method, I get the following:

expected: 1.2 but was : 1.2000000000000002

I've tried numerous ways of removing the decimal place but I haven't seemed to found a way. Also is it possible to perform this logic with the .round() methods in Java?

CodePudding user response：

With the primitive type double you can't express exact numbers, due to numerical issues. Try using BigDecimal instead and the .divide() method. There you can also set the scale to 2 (2 decimal places) and the RoundingMode (usually HALF_UP)

CodePudding user response：

Multiply your result by 100, parse it to an Integer, divide it by hundred and parse it back to a double.

int temp = (int)(total * 100.0);
double finalValue = (double)(temp / 100.0);