BigDecimal 类型: BigDecimal bb =list.stream().map(Plan::getAmount).reduce(BigDecimal.ZERO,BigDecimal::add); int、double、long 类型: double max = list.stream().mapToDouble(User::getHeight).sum();
Stream常用操作
原文：https://www.cnblogs.com/liheng2233/p/14631132.html
