Java入门第三季 6-5 作业

 package com.v512;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

public class testSort {
 public void test(){
    List<String> listString=new ArrayList<String>();
     String str ="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; 
    Random random=new Random();  
    for(int j=0;j<10;j++){
        StringBuffer sb = new StringBuffer(); 
    int k=random.nextInt(9)+1;
     do{
     for(int i=0;i<k;i++){
           int number = random.nextInt(str.length());     
         sb.append(str.charAt(number));  
        } 
     } while(listString.contains(sb)) ;
        listString.add(sb.toString());    
    }

    for(String string:listString){
    System.out.println("字符串："+string);
    }
    System.out.println("------------排序后-------------");
    Collections.sort(listString);
    for(String string2:listString){
    System.out.println("字符串："+string2);
    }
 }  
    public static void main(String[] args){
        testSort ts=new testSort();
        ts.test();

    }
    }