Numbers and Dates - Java 8 Recipes - page 104

In the end, the same results will be returned using either compareTo() or com-
pare() .
4-5. Calculating Monetary Values
Problem
You are developing an application that requires the use of monetary values and you are
not sure which data type to use for storing and calculating currency values.
Solution
Use the BigDecimal data type to perform calculation on all monetary values. Format
the resulting calculations using the NumberFormat.getCurrencyInstance()
helper method. In the following code, three monetary values are calculated using a
handful of the methods that are part of the BigDecimal class. The resulting calcula-
tions are then converted into double values and formatted using the Number-
Format class. First, take a look at how these values are calculated:
BigDecimal currencyOne = new BigDecimal("25.65");
BigDecimal currencyTwo = new BigDecimal("187.32");
BigDecimal currencyThree = new BigDecimal("4.86");
BigDecimal result = null;
String printFormat = null;
// Add all three values
result = currencyOne.add(currencyTwo).add(currencyThree);
// Convert to double and send to formatDollars(),
returning a String
printFormat = formatDollars(result.doubleValue());
System.out.println(printFormat);
// Subtract the first currency value from the second
result = currencyTwo.subtract(currencyOne);
printFormat = formatDollars(result.doubleValue());
System.out.println(printFormat);