参考了其他同学的思路，简化了一下自己的算法，源文件为Test.java

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

public class Test03 {
    private static List<String> stringList;
    private static String finalString;

    public static void main(String[] args) {
        stringList = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            do {
                createString();
            } while (stringList.contains(finalString));
            stringList.add(finalString);
        }

        System.out.println("————————————————————————排序前——————————————————————————");
        listOut(stringList);
        Collections.sort(stringList);
        System.out.println("————————————————————————排序后——————————————————————————");
        listOut(stringList);
    }

    private static void createString() {
        Random random = new Random();
        StringBuffer sb = new StringBuffer();
        int length = random.nextInt(10)+1;
        for (int i = 0; i < length; i++) {

            //以下为Test02.java的改进之处
            String raw = "123456789QWERTYUIOPASDFGHJKLZXCVBNMqwertyuiopasdfghjklzxcvbnm";
            sb.append(raw.charAt(random.nextInt(raw.length())));

        }

        finalString = sb.toString();

    }

    private static void listOut(List<String> stringList) {
        for (String string : stringList) {
            System.out.println("元素："+string);
        }
    }

}