public class Work {
    private List<String> list;
    private String string;
    private int len;
    public Work() {
        this.list = new ArrayList<>();
        string = "QWERTYUIOPASDFGHJKLZXCVBNMqwertyuiopasdfghjklzxcvbnm0123456789";
        len = string.length();
    }

    public void testSort() {
        Random random = new Random();
        for (int i = 0; i < 10; i++) {//添加十条随机字符串
            StringBuilder stringBuilder = new StringBuilder();
            do {
                int k = random.nextInt(10);//每条字符串长度为10以内的随机数
                for (int j = 0; j <= k; j++) {
                    stringBuilder.append(string.charAt(random.nextInt(len)));
                }
            } while (list.contains(stringBuilder.toString()));//每条字符串不可重复
            list.add(stringBuilder.toString());
        }

        System.out.println("-------排序前-----------");
        for (String string : list) {
            System.out.println("元素："+string);
        }

        Collections.sort(list);
        System.out.println("-------排序后-----------");
        for (String string : list) {
            System.out.println("元素："+string);
        }
    }

    public static void main(String[] args) {
        Work work = new Work();
        work.testSort();
    }
}

运行结果：
-------排序前-----------
元素：Lq4F
元素：Nwc
元素：xix3
元素：CiOc
元素：VhdfyCi8o
元素：TtIx6
元素：rK7eSvu5F
元素：yB
元素：y
元素：F71KXRAC
-------排序后-----------
元素：CiOc
元素：F71KXRAC
元素：Lq4F
元素：Nwc
元素：TtIx6
元素：VhdfyCi8o
元素：rK7eSvu5F
元素：xix3
元素：y
元素：yB