請幫忙，while循環和標記器和讀取文件

Question

顯然，我需要幫助。我們的任務是檢索文件並對其進行分類並將其顯示在另一個文件中。姓氏名然後等級。由於錯誤「java.util.NoSuchElementException」而導致出現循環時遇到問題。只有在我循環訪問時更改當前存在的內容時纔會發生此問題。我也有顯示結果的問題。我展示的結果都在一行中，我不能讓它發生。我們不允許使用數據列表，Bufferedreader，掃描儀以及我已有的內容。這是我到目前爲止的代碼：

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()); 
     } 

    } 
} 

我輸入文件看起來像這樣：

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) 

這將有助於點東西出來，以防萬一我不跟着你一路過關斬將。

Answer 1

找到問題的簡單方法是將大部分代碼註釋掉，然後逐個查找每個步驟。因此，從能夠讀取文件開始。然後打印到屏幕上。然後將組織的數據打印到屏幕上。最後將組織的數據打印到文件中。

這應該是一個相當簡單的