一、sorted 函数

对流进行自然排序，其中的元素必须实现Comparable 接口
sorted(Comparator<? super T>comparator) 用来自定义升降序

二、limit 函数

获取指定数量的元素
(limit(long maxSize);
场景：成绩前几，积分排名等

三、实战

package com.learning.javalearning.lambda.chapter5;

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;

public class Sorted_LimitedDemo {
    public static void main(String[] args) {


        List<String> list = Arrays.asList("Spring Boot", "Python", "微服务", "高并发", "Redis", "MongoDB");
        List<String> resultList = list.stream()
                .sorted()
                .collect(Collectors.toList());
        System.out.println(">> sorted() 默认升序：");
        System.out.println(resultList + "\n");

        Collections.reverse(resultList);
        System.out.println(">> 使用翻转Collections.reverse(list)：及降序");
        System.out.println(resultList + "\n");

        resultList = list.stream()
                .sorted(Comparator.comparing(obj -> obj.length()))
                .collect(Collectors.toList());
        System.out.println(">> 自定义--按照长度排序，默认升序：");
        System.out.println(resultList + "\n");


        resultList = list.stream()
                .sorted(Comparator.comparing(String::length).reversed())
                .collect(Collectors.toList());
        System.out.println(">> 使用翻转reversed()：及降序");
        System.out.println(resultList + "\n");

        resultList = list.stream()
                .sorted(Comparator.comparing(String::length).reversed())
                .limit(3)
                .collect(Collectors.toList());
        System.out.println(">> limit(3)：获取前3");
        System.out.println(resultList + "\n");
    }
}