作业作业，感觉自己写的一般

package com.imooc6;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;
        public class CollectionsTesta {		
        /**	
        * 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以内的随机数	
        * 3.每条字符串的每个字符都为随机生产的字符，字符可以重复	
        * 4.每条随机字符串不可重复	
        */	
              public void testString(){		
                List<String> listString=new ArrayList<String>();		
                Random random=new Random();		
                Random random1=new Random();		
                String strs="0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM";		
                StringBuilder str;		
                int b;		
                int a;		
                     for(int j=0;j<10;j++){			
                         str=new StringBuilder();			
                         b=random.nextInt(10)+1;		
                            for(int i=0;i<b;i++){			
                            a=random1.nextInt(62);		
                            str.append(strs.charAt(a));		
                          }		
                          listString.add(str.toString());	
                        }		
                        System.out.println("-------排序前-------");		
                        for (String string : listString) {			
                           System.out.println("元素："+string);		
                           }		
                           Collections.sort(listString);		
                           System.out.println("-------排序后-------");		
                        for (String string : listString) {			
                        System.out.println("元素："+string);		
                        }	
                      }	
                      /**	
                      * @param args	
                      */	
             public static void main(String[] args) {	// TODO Auto-generated method stub		
             
             CollectionsTesta ct=new CollectionsTesta();		
             ct.testString();	
             }
             }