Java8中Stream流求最大值最小值怎么实现

一、BigDecimal 求最大值和最小值

1. stream().reduce()实现

List<BigDecimal> list = new ArrayList<>(Arrays.asList(new BigDecimal("1"), new BigDecimal("2")));
BigDecimal max = list.stream().reduce(list.get(0), BigDecimal::max);
BigDecimal min = list.stream().reduce(list.get(0), BigDecimal::min);

2. stream().max()或stream().min()实现

List<BigDecimal> list = new ArrayList<>(Arrays.asList(new BigDecimal("1"), new BigDecimal("2")));
BigDecimal max = list.stream().max(Comparator.comparing(x -> x)).orElse(null);
BigDecimal min = list.stream().min(Comparator.comparing(x -> x)).orElse(null);

二、Integer 求最大值和最小值

1. stream().reduce()实现

List<Integer> list = new ArrayList<>(Arrays.asList(1, 2));
Integer max = list.stream().reduce(list.get(0), Integer::max);
Integer min = list.stream().reduce(list.get(0), Integer::min);

2. Collectors.summarizingInt()实现

List<Integer> list = new ArrayList<>(Arrays.asList(1, 2));
IntSummaryStatistics intSummaryStatistics = list.stream().collect(Collectors.summarizingInt(x -> x));
Integer max = intSummaryStatistics.getMax();
Integer min = intSummaryStatistics.getMin();

3. stream().max()或stream().min()实现

List<Integer> list = new ArrayList<>(Arrays.asList(1, 2));
Integer max = list.stream().max(Comparator.comparing(x -> x)).orElse(null);
Integer min = list.stream().min(Comparator.comparing(x -> x)).orElse(null);

知识来源：

Java8中Stream流求最大值最小值怎么实现-PHP博客-李雷博客