java第三季6-5课后练习:随机字符串;

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

public void testSort3() {
        List<String> stringList=new ArrayList<String>();
        String str ="abcdefghijklmnopqrstuvwxyz0123456789";
        Random random = new Random();
        for(int i=0;i<10;i++) {
            StringBuffer sb= new StringBuffer();//循环重置
            do {
            for(int j=0;j<random.nextInt(10)+1;j++) {//+1保证至少有一个字符
                int number =random.nextInt(str.length());
                sb.append(str.charAt(number));
                //不要在for外赋值number，不然选择的字符都是同一个下标
            }
            }while(stringList.contains(sb));//do-while防重复
                stringList.add(sb.toString());
        }
        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);
        }
    }