java第三季<6-5>：生成随机字符串列表并进行排序

package com.imooc.collection;

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

• 3.创建完List<String>之后，往其中添加十条随机字符串
• 每条字符串长度为10以内的随机整数
• 每条字符串的每个字符都为随机产生的字符，字符可以重复

• 每条随机字符串不可重复
  */
  public class CollectionTest {
  public String getRandomString(){
  String base = "0123456789abcdefghijklmnopqrstuvwxyz";
  Random random = new Random();
  int k=random.nextInt(10) ;
  StringBuffer sb = new StringBuffer();
  for(int i=0;i<k;i++){
  int number = random.nextInt(base.length());
  sb.append(base.charAt(number));
  }
  return sb.toString();
  }
  public void testsort3(){
  List<String> stringList2 = new ArrayList<>();
  CollectionTest ct = new CollectionTest();
  String randomString;
  //往列表里添加10个不重复的随机字符串，调用getRandomString()方法获得随机字符串
  for(int i=0;i<10;i++){
  do{
  randomString = ct.getRandomString();
  }while(stringList2.contains(randomString));
  stringList2.add(randomString);
  System.out.println("成功添加随机字符串：" + randomString);
  }

   System.out.println("----------排序前---------------");
   for(String string:stringList2){
       System.out.println("元素：" + string);
   }
  
   System.out.println("----------排序后---------------");
   Collections.sort(stringList2);
   for(String string:stringList2){
       System.out.println("元素：" + string);
   }

  }
  public static void main(String[] args) {
  CollectionTest ct = new CollectionTest();
  ct.testsort3();
  }
  }