JDK新特性关于流操作部分
菜鸡开发阿飞 人气:1// 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
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