sum of BigDecimal List using streams and sum method

问题

If we have all int or long or other primitive datatype value in list then we obtain sun of all values using

return items.stream().mapToInt(i -> i).sum();

I have list of BigDecimal values,how to find the sum of all values using Java8

As there is no default method like mapToBigDecimal I tried to create plain map but then I cannot use sum()

回答1:

List<BigDecimal> items = Arrays.asList(BigDecimal.ONE, BigDecimal.valueOf(1.5), BigDecimal.valueOf(100));
items.stream().reduce(BigDecimal.ZERO, BigDecimal::add);

Though Answer provided by Lisq199 works but I am in favor of including Holger and Klitos comments,This handles No values and always returns a value

回答2:

You can use Stream#reduce(BinaryOperator).

A simple example:

List<BigDecimal> items = Arrays.asList(BigDecimal.ONE, BigDecimal.valueOf(1.5), BigDecimal.valueOf(100));
items.stream().reduce((i, j) -> i.add(j)).ifPresent(System.out::println);
// Outputs 102.5

来源：https://stackoverflow.com/questions/41966808/sum-of-bigdecimal-list-using-streams-and-sum-method