JDK新特性关于流操作部分

    // array 工具类   可以用来快捷的将数组转化为list

        List<String> strings = Arrays.asList("zhongguo", "riben", "yingguo");

        // 转化为一个新的list

        List<String> collect = strings.stream().map(number -> number += "dfvgcdvcx").collect(Collectors.toList());

        // 流输出

        collect.forEach(num -> System.out.println( num));

        // 帅选偶数

        List<Integer> numberList = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9);

        List<Integer> collect1 = numberList.stream().filter(num -> num % 2 == 0).collect(Collectors.toList());

        collect1.forEach(number -> System.out.println(number));

        // 从无线流数据中选择第一个

        List<Integer> numberList1= Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9);

        Optional<Integer> first = numberList1.stream().findFirst();

        // 输出第一个

        System.out.println(first.orElse(-1));

        // 获取或者扔掉前 n 个元素

        List<Integer> ageList = Arrays.asList(11, 22, 13, 14, 25, 26);

        Stream<Integer> limit = ageList.stream().limit(4);

        limit.forEach(li -> System.out.println(li));

        Stream<Integer> skip = ageList.stream().skip(4);

        skip.forEach(sk-> System.out.println(sk));

       // 数学统计功能

        List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6);

        IntSummaryStatistics intSummaryStatistics = list.stream().mapToInt(x -> x).summaryStatistics();

        System.out.println(intSummaryStatistics.getMax());

        System.out.println(intSummaryStatistics.getMin());

        System.out.println(intSummaryStatistics.getAverage());

        System.out.println(intSummaryStatistics.getCount());

        System.out.println(intSummaryStatistics.getSum());

        // 分组聚合功能

        List<Integer> groupList = Arrays.asList(11, 22, 13, 14, 25, 26);

        Map<Integer, List<Integer>> collect2 = groupList.stream().collect(Collectors.groupingBy(age -> age / 10));

        collect2.forEach((k,v) -> System.out.println(k+"nmnmn"+v));

        // 按某个条件分组 会得到一个key  为布尔的map

        List<Integer> patationList = Arrays.asList(11, 22, 13, 14, 25, 26);

        Map<Boolean, List<Integer>> collect3 = patationList.stream()

                .collect(Collectors.partitioningBy(age -> age > 18));

        // 生成自己的 Stream 流

        Random random = new Random();

        Stream<Integer> generate = Stream.generate(random::nextInt);

        generate.forEach(num -> System.out.println(num));

        // 生成自己的 UUID 流

        Stream<UUID> generate1 = Stream.generate(UUID::randomUUID);

        generate1.limit(5).forEach(System.out::println);

JDK新特性关于流操作部分