java八股文面试[java基础]——笔试用Stream求列表中最大值、最小值

àì夳堔傛蜴生んèń 2024-03-24 21:50 25阅读 0赞

## 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][Java8_Stream_-PHP_-]

[Java8_Stream_-PHP_-]: https://www.mdaima.com/it/9012.html