随便记点

public class Stream {
    public static void main(String[] args) {
        // 1. map
        List<Integer> integerList = Arrays.asList(1, 2, 2, 5, 7, -3, 3);
        List<Integer> integers = integerList.stream().map(i -> i * i).distinct().collect(Collectors.toList());
        for (Integer integer : integers) {
            System.out.println(integer);
        }
        // 1.5. 统计
        IntSummaryStatistics stats = integerList.stream().mapToInt((x) -> x).summaryStatistics();
        System.out.println("列表中最大的数 : " + stats.getMax());
        System.out.println("列表中最小的数 : " + stats.getMin());
        System.out.println("所有数之和 : " + stats.getSum());
        System.out.println("平均数 : " + stats.getAverage());
        // 2. filter
        long count = integerList.stream().filter(i -> i != 2).count();
        System.out.println(count);
        // 3. limit & forEach
        Random random = new Random();
        random.ints().limit(10).forEach(System.out::println);
        // 4. sored
        random.ints().limit(10).sorted().forEach(System.out::println);
        // 5. Collectors
        List<String> strings = Arrays.asList("abc", "", "bc", "efg", "abcd","", "jkl");
        String newString = strings.stream().filter(string -> !string.isEmpty()).collect(Collectors.joining(","));
        System.out.println(newString);
    }
}