Java Money - Sum up monetary amounts

Java Money (JSR-354) provides an excellent API (and SPI) to deal with money in Java. The following example shows how easily it can be used with Java Streams to sum up MonetaryAmounts.

Given the following list with two monetary amounts of CHF 12.50 and CHF 99.35

we can easily calculate the grand total (sum up the monetary amounts) by using Java Streams. Note that Money is backed by a BigDecimal so precision is respected. For the sake of readability the code examples are working with double values.

The result is a monetary amount sum with CHF 111.85. Neat, isn't it?

But why MonetaryFunctions?

The example above uses MonetaryFunctions::sum to sum up the monetary amounts. Of course you could simply use MonetaryAmount::add as shown in the listing below.

By using MonetaryFunctions::sum you make sure, that only monetary amounts of the same currency are summed up. If you try to sum up CHF 5.50 and $ 12.33 using MonetaryAmount::add, you then get MonetaryException.