Java8中Stream流求最大值最小值

港控/mmm° 2023-09-30 19:29 26阅读 0赞

#### 文章目录 ####

*  java中各种类型用Stream流求最大值最小值
 *   *  一、BigDecimal 求最大值和最小值
     *   *  1. stream().reduce()实现
         *  2. stream().max()或stream().min()实现
     *  二、Integer 求最大值和最小值
     *   *  1. stream().reduce()实现
         *  2. Collectors.summarizingInt()实现
         *  3. stream().max()或stream().min()实现
     *  三、Long 求最大值和最小值
     *   *  1. stream().reduce()实现
         *  2. Collectors.summarizingLong()实现
         *  3. stream().max()或stream().min()实现
     *  四、Double 求最大值和最小值
     *   *  1. stream().reduce()实现
         *  2. Collectors.summarizingLong()实现
         *  3. stream().max()或stream().min()实现

## java中各种类型用Stream流求最大值最小值 ##

### 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);

### 三、Long 求最大值和最小值 ###

#### 1. stream().reduce()实现 ####

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

#### 2. Collectors.summarizingLong()实现 ####

List<Long> list = new ArrayList<>(Arrays.asList(1L, 2L));
            LongSummaryStatistics summaryStatistics = list.stream().collect(Collectors.summarizingLong(x -> x));
            Long max = summaryStatistics.getMax();
            Long min = summaryStatistics.getMin();

#### 3. stream().max()或stream().min()实现 ####

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

### 四、Double 求最大值和最小值 ###

#### 1. stream().reduce()实现 ####

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

#### 2. Collectors.summarizingLong()实现 ####

List<Double> list = new ArrayList<>(Arrays.asList(1d, 2d));
            DoubleSummaryStatistics summaryStatistics = list.stream().collect(Collectors.summarizingDouble(x -> x));
            Double max = summaryStatistics.getMax();
            Double min = summaryStatistics.getMin();

#### 3. stream().max()或stream().min()实现 ####

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