请帮忙，while循环和标记器和读取文件

Question

显然，我需要帮助。我们的任务是检索文件并对其进行分类并将其显示在另一个文件中。姓氏名然后等级。由于错误“java.util.NoSuchElementException”而导致出现循环时遇到问题。只有在我循环访问时更改当前存在的内容时才会发生此问题。我也有显示结果的问题。我展示的结果都在一行中，我不能让它发生。我们不允许使用数据列表，Bufferedreader，扫描仪以及我已有的内容。这是我到目前为止的代码：

import java.util.; 
import java.util.StringTokenizer; 
import java.io.; 
import javax.swing.*; 
import java.text.DecimalFormat; 
/************************************* 
Program Name: Grade 
Name: Dennis Liang 
Due Date: 3/31/11 
Program Description: Write a program 
which reads from a file a list of 
students with their Grade. Also display 
last name, first name, then grade. 
************************************/ 

import java.util.*; 
import java.util.StringTokenizer; 
import java.io.*; 
import javax.swing.*; 
import java.text.DecimalFormat; 

class Grade { 
    public static void main(String [] args)throws IOException { 
     //declaring  
     String line = ""; 
     StringTokenizer st; 
     String delim = " \t\n\r,-"; 
     String token; 
     String firstname; 
     String lastname; 
     String grade; 
     String S69andbelow="Students with 69 or below\n"; 
     String S70to79 ="Students with 70 to 79\n"; 
     String S80to89= "Students with 80 to 89\n"; 
     String S90to100= "Students with 90 to 100\n"; 
     int gradeint; 
     double gradeavg = 0; 
     int count = 0; 
     File inputFile = new File("input.txt"); 
     File outputFile = new File("output.txt"); 
     FileInputStream finput = new FileInputStream(inputFile); 
     FileOutputStream foutput = new FileOutputStream(outputFile); 

     FileReader reader = new FileReader(inputFile); 
     BufferedReader in = new BufferedReader(reader); 

     Scanner std = new Scanner(new File("input.txt")); 

     Scanner scanner = new Scanner(inputFile); 

     BufferedWriter out = new BufferedWriter(new FileWriter(outputFile)); 

     Scanner scan = new Scanner(S69andbelow);   
     //reading linev 
     line = scanner.nextLine(); 

     st = new StringTokenizer(line, delim); 
     //avoiding selected characters 
     try { 
      while(st.hasMoreTokens()) { 
       firstname = st.nextToken(); 
       lastname = st.nextToken(); 
       grade = st.nextToken(); 
       //storing tokens into their properties 

       gradeint = Integer.parseInt(grade); 
       //converting token to int 

       gradeavg = gradeavg + gradeint; 
       //calculating avg 

       count++; 
       //recording number of entries 

        if (gradeint <=69) { 
         S69andbelow = S69andbelow + lastname + " " 
           + firstname + " " + "\t" + grade + "\n"; 
        } // saving data by grades      
        else if (gradeint >= 70 && gradeint <= 79) { 
         S70to79 = S70to79 + lastname + " " + firstname 
           + " " + "\t" + grade + "\n"; 
        } // saving data by grades 

        else if (gradeint >= 80 && gradeint <=89) { 
         S80to89 = S80to89 + lastname + " " + firstname 
           + " " + "\t" + grade + "\n"; 
        } // saving data by grades     
        else { 
         S90to100 = S90to100 + lastname + " " + firstname 
           + " " + "\t" + grade + "\n"; 
        } // saving data by grades 


       }//end while 

      System.out.println(S69andbelow + "\n" + S70to79 + "\n" 
         + S80to89 + "\n" + S90to100); 
      //caterorizing the grades 

      gradeavg = gradeavg/count; 
      //calculating average 

      DecimalFormat df = new DecimalFormat("#0.00"); 

      out.write("The average grade is: " 
         + df.format(gradeavg)); 

      System.out.println("The average grade is: " 
         + df.format(gradeavg)); 

      Writer output = null;    

      output = new BufferedWriter(new FileWriter(outputFile)); 

      // scanner.nextLine(S69andbelow); 
      //output.write(S69andbelow + "\n" + S70to79 + "\n" 
      //    + S80to89 + "\n" + S90to100); 
      // output.close(); 


     } 
     catch(Exception e) { 
       System.out.println(e.toString()); 
     } 
     // Close the stream 
     try { 
      if(std != null) 
       std.close(); 
     } 
     catch(Exception e) { 
      System.out.println(e.toString()); 
     } 

    } 
} 

我输入文件看起来像这样：

Bill Clinton 85 (enter) 
Al Gore 100 (enter) 
George Bush 95 (enter) 
Hillery Clinton 83(enter) 
John McCain 72(enter) 
Danna Green 87(enter) 
Steve Delaney 76(enter) 
John Smith(enter) 
Beth Bills 60(enter) 

这将有助于点东西出来，以防万一我不跟着你一路过关斩将。

Answer 1

找到问题的简单方法是将大部分代码注释掉，然后逐个查找每个步骤。因此，从能够读取文件开始。然后打印到屏幕上。然后将组织的数据打印到屏幕上。最后将组织的数据打印到文件中。

这应该是一个相当简单的