while while while while for text file not functioning

Question

我需要在文本文件中读取未知数量的问题。格式总是相同的，但选项的数量不是。我用for循环来处理这个问题。

如果我删除了这段时间，代码成功获取其中一个问题并存储它，但我需要它循环。代码甚至不会用循环进行编译。我尝试了很多修复，但它不会编译。

任何意见非常感谢！

FileReader fileReader = new FileReader(f); 

     BufferedReader bufferedReader = 
     new BufferedReader(fileReader); 

     String line; 

      do { 
       line = bufferedReader.readLine(); 
       String question = line; 

       line = bufferedReader.readLine(); 
       int numoptions = Integer.parseInt(line); 

       ArrayList<String> options = new ArrayList<>(); 
       for (int i = 0; i < numoptions; i++){ 
        line = bufferedReader.readLine(); 
        String choice = line; 
        options.add(choice); 
       } 

       line = bufferedReader.readLine(); 
       int answer = Integer.parseInt(line); 

       line = bufferedReader.readLine(); 
       int tries = Integer.parseInt(line); 

       line = bufferedReader.readLine(); 
       int wins = Integer.parseInt(line);   

       Question objQ = new Question(question, numoptions, options,   answer, tries, wins); 
       mainlist.add(objQ); 

      } 
      while (bufferedReader.readLine() != null); 

       bufferedReader.close(); 

Answer 1

在你的while语句，你做一个bufferedReader.readLine（），从中你不使用的结果。这可能不是你想要做的。

请看下面的代码，应该编译和阅读你的问题文本文件（假设这是一个整数每行）。

import java.io.BufferedReader; 
import java.io.File; 
import java.io.FileReader; 
import java.io.IOException; 
import java.util.ArrayList; 


public class ReadQuestions { 

    static ArrayList<Question> mainlist = new ArrayList<>(); 


    static void readFile(File f) throws IOException { 
     FileReader fileReader = new FileReader(f); 

     BufferedReader bufferedReader = 
       new BufferedReader(fileReader); 

     String line; 


     while(true) { 

      line = bufferedReader.readLine(); 
      if(line == null) 
       break; 
      System.out.println(line); 
      String question = line; 

      line = bufferedReader.readLine(); 
      int numoptions = Integer.parseInt(line); 

      ArrayList<String> options = new ArrayList<>(); 
      for (int i = 0; i < numoptions; i++) { 
       line = bufferedReader.readLine(); 
       String choice = line; 
       options.add(choice); 
      } 

      line = bufferedReader.readLine(); 
      int answer = Integer.parseInt(line); 

      line = bufferedReader.readLine(); 
      int tries = Integer.parseInt(line); 

      line = bufferedReader.readLine(); 
      int wins = Integer.parseInt(line); 


      Question objQ = new Question(question, numoptions, options,   answer, tries, wins); 
      mainlist.add(objQ); 
     } 
     bufferedReader.close(); 
    } 

    public static void main(String []arg) throws IOException { 
     File f = new File("questions.txt"); 
     readFile(f); 
    } 


    public static class Question { 
     public Question(String question, int numoptions, ArrayList<String> options, int answer, int tries, int wins) { 
      // tbc 
     } 
    } 


} 

Answer 2

我建议你做一个while loop而不是do ... while。那么你不应该在循环中调用多个readLine调用。一开始我会这样做。我知道这不是最终的，因为我不知道你的文件是什么样的。

String line = null; 
while ((line = bufferedReader.readLine()) != null) { 
     String question = line; 
     int numoptions = Integer.parseInt(line); 

     ArrayList<String> options = new ArrayList<>(); 
     for (int i = 0; i < numoptions; i++) { 
      String choice = line; 
      options.add(choice); 
     } 

     int answer = Integer.parseInt(line); 
     int tries = Integer.parseInt(line); 
     int wins = Integer.parseInt(line);   

     Question objQ = new Question(question, numoptions, options, answer, tries, wins); 
     mainlist.add(objQ); 
} 
bufferedReader.close(); 

查看文件后我可能会这样做。我猜你现在可以自己完成它：

int i = 0; 
while ((line = bufferedReader.readLine()) != null) { 
    i++; 
    switch(i) 
    { 
     case 1: String question = line; 
     break; 

     case 2: 
     int numoptions = Integer.parseInt(line); 
     ArrayList<String> options = new ArrayList<>(); 
     for (int i = 0; i < numoptions; i++) { 
       String choice = line; 
       options.add(choice); 
     } 
     break;