import java.util.ArrayList;import java.util.Arrays;import java.util.Collections;import java.util.List;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(list);        for (String s : Arrays.asList(list.toString(), "missing number: " + found, removed == found ? "测试成功" : "测试失败")) {            System.out.println(s);        }    }    static int findMissingNumber(List<Integer> list) {        int sum = 0;        for (int i = 10; i <= 20; i++) {            sum += i;        }        for (Integer integer : list) {            sum -= integer;        }        return sum;    }}