package com.github.hcsp.sql;import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.List;/** * Created by chengww on 2019/10/10. */public class Main {    public static void main(String[] args) {        // 构造从start到end的序列：        final int start = 10;        final int end = 20;        List<Integer> list = new ArrayList<>();        for (int i = start; i <= end; i++) {            list.add(i);        }        // 洗牌算法 shuffle 可以随机交换List中的元素位置:        Collections.shuffle(list);        // 随机删除List中的一个元素:        int removed = list.remove((int) (Math.random() * list.size()));        int found = findMissingNumber(start, end, list);        System.out.println(list.toString());        System.out.println("missing number: " + found);        System.out.println(removed == found ? "测试成功" : "测试失败");    }    static int findMissingNumber(int start, int end, List<Integer> list) {        list.sort(Comparator.comparingInt(e -> e));        return list.stream().filter(element -> start + list.indexOf(element) != element)                .findFirst().map(integer -> integer - 1).orElse(0);    }}