所以我是ArrayList的新手，我很少使用do while循环

Question

所以这里是Pschemo我的整个代码，非常感谢，没有问题没有错误，一切都很好。但是，当我第一次输入数组的所有元素并输入stop时，只需要一件事，我在编写System.out.println（）时会移动一行，然后我必须再次按Enter键，然后它显示了我设计的Thank You消息和Output的其余部分。为什么会这样？

任何线索？

  import java.util.ArrayList;
 import java.util.Scanner;
 import java.util.concurrent.TimeUnit;

     class End_Start_Vowels
      {
public static void main() throws InterruptedException
{
  String fs="yes";
  while(fs.equalsIgnoreCase("yes"))
  {

      Scanner in=new Scanner(System.in);
      ArrayList <String> a= new ArrayList<String>();
      String b; int c=0;
     char d;
      int total=0;
     int v=0;
     int o=0;
     int w=0;
     int e=0;
     int l=0;
      System.out.println("start tping below, type stop or end to stop.");
      do
      {
        b=in.nextLine();
        a.add(b);
        c++;
      }
      while(!b.equalsIgnoreCase("stop")&&!b.equalsIgnoreCase("end"));

     if(c<2)
      a.clear();

       int z=a.size();
       if(c>=2)
       a.remove(z-1);
      System.out.println();

        if(c<2)
         System.out.println("No word are typed. Please type continue  to restart it");
        String s1=in.nextLine();

       if(c<2)
         {   if(s1.equalsIgnoreCase("continue")){
        System.out.println("start tping below, type stop or end to stop.");
         do
        {
        b=in.nextLine();
        a.add(b);
        c++;
           }
        while(!b.equalsIgnoreCase("stop")&&!b.equalsIgnoreCase("end"));

        if(c<2)
        a.clear();

        z=a.size();
       if(c>=2)
       a.remove(z-1);
       System.out.println();
      for(int j=0;j<a.size();j++)
      {
        String s=a.get(j);

        for(int i=0;i<s.length();i++)
           {
             d=s.charAt(i);


            if(d=='a'||d=='A')
            {v++; total++;}
              if(d=='E'||d=='e')
             { o++; total++;}
              if(d=='i'||d=='I')
             {w++; total++;}
            if(d=='O'||d=='o')
            { e++; total++;}
            if(d=='u'||d=='U')
            { l++; total++;}
           }
      }
      if(c>=2)
       {
            System.out.println("Thanks for using!");
          TimeUnit.SECONDS.sleep(1);

         System.out.println("Showing you the frequencies of each vowels.");
        TimeUnit.SECONDS.sleep(1);
        System.out.println();
        System.out.println("Frequency of vowel a is ="+v);
        System.out.println("Frequency of vowel e is ="+o);
        System.out.println("Frequency of vowel i is ="+w);
        System.out.println("Frequency of vowel o is ="+e);
        System.out.println("Frequency of vowel u is ="+l);
         System.out.println();
        System.out.println("Total number of vowels present is ="+total);
     }
    }

}
else
{ 
      for(int j=0;j<a.size();j++)
      {
        String s=a.get(j);

        for(int i=0;i<s.length();i++)
           {
             d=s.charAt(i);


            if(d=='a'||d=='A')
            {v++; total++;}
              if(d=='E'||d=='e')
             { o++; total++;}
              if(d=='i'||d=='I')
             {w++; total++;}
            if(d=='O'||d=='o')
            { e++; total++;}
            if(d=='u'||d=='U')
            { l++; total++;}
           }
      }
      if(c>=2)
       {
            System.out.println("Thanks for using!");
          TimeUnit.SECONDS.sleep(1);

         System.out.println("Showing you the frequencies of each vowels.");
        TimeUnit.SECONDS.sleep(1);
        System.out.println();
        System.out.println("Frequency of vowel a is ="+v);
        System.out.println("Frequency of vowel e is ="+o);
        System.out.println("Frequency of vowel i is ="+w);
        System.out.println("Frequency of vowel o is ="+e);
        System.out.println("Frequency of vowel u is ="+l);
         System.out.println();
        System.out.println("Total number of vowels present is ="+total);
     }
    }
       System.out.println();
   TimeUnit.SECONDS.sleep(1);
   System.out.println("Do you want to use it again, type yes to continue.");
   fs=in.nextLine();
   System.out.println();
 }
}
}