1.创建完List<String>之后，往其中添加十条随机字符串
2.每条字符串的长度为10以内的随机整数
3.每条字符串的每个字符都为随机生成的字符，字符可以重复
4.每条随机字符串不可重复

package com.imooc.collection;

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

public class StringCollectionsSort {

    public void testSort(){
    String base = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"; 
    List<String> stringList=new ArrayList<String>();
    Random random=new Random();
     for(int i=0;i<10;i++){ 
         StringBuilder sb = new StringBuilder();
        int j=random.nextInt(9)+1;
         do{
         for(int k=0;k<j;k++){
             int m = random.nextInt(base.length());   
            sb.append(base.charAt(m)); 
         } 
         }while(stringList.contains(sb));
         stringList.add(sb.toString());
        System.out.println("成功添加字符串："+sb); 

     }
     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);
     }
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        StringCollectionsSort gs=new StringCollectionsSort();
        gs.testSort();

    }

}