public void testPractice(){
    List<String> stringList = new ArrayList<String>();
    Random random = new Random();
    StringBuffer sb=new StringBuffer();
    String str="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    Integer k;
    do{
        //循环10次生成10个随机字符串
    for(int i=0;i < 10;i++){
        //通过循环控制字符串的长度不大于10
        k = random.nextInt(10);
        for(int j=0;j < k;j++){
            //随机生成字符
            int number = random.nextInt(62);
            sb.append(str.charAt(number));
        }
        stringList.add(sb.toString());
        System.out.println("随机生成的字符串为：" + sb.toString());
        sb.setLength(0);
    }
    }while(stringList.contains(stringList));

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