从txt文件收集信息

Question

文件花名册: roster.txt

Reagan rebradshaw835
Ryley rbarber894
Peyton pstott885
Tyrese tmayo945
Caius ccharlton329

该程序必须处理异常处理。我目前正在努力克服的问题是能够获得适当的输出。我不知道是否有一种特定的方法可以找到包含名称的行，并返回行中除名称之外的所有内容。这样我们就可以返回分配的用户名。

例如，第一行显示：

Reagan rebradshaw835

方法仅返回rebradshaw835

下面是代码：(更新代码) vhthanh真的帮助我理解了如何读取文件！我决定使用替换字符串命令来编辑代码。如果没有vhthanhI，可能不会学习如何与文件交互。

    package chapter11;
import java.util.Scanner;
import java.io.FileInputStream;
import java.io.IOException;

public class LabProgram {
   
   public static String findID(String studentName, Scanner infoScnr) throws Exception {
    
       while (infoScnr.hasNextLine()) {
           
            String line = infoScnr.nextLine();
            //String[] values = line.split(" ", 2);
            
                        
            if (line.contains(studentName)) {
                
                line = line.replace(studentName + " ", "");
            
            return line;    
                
                
            }
               
               
           }
       
       throw new Exception ("Student ID not found for " + studentName);
        
        
       }
   
   public static String findName(String studentID, Scanner infoScnr) throws Exception {
       
       while (infoScnr.hasNextLine()) {
           
        String line = infoScnr.nextLine();
        //String[] values = line.split(" ", 2);
        
                    
        if (line.contains(studentID)) {
            
            line = line.replace(studentID + " ", "");
        
        return line;    
            
            
        }
           
           
       }
       
       throw new Exception ("Student name not found for " + studentID);
    
   }
   
   public static void main(String[] args) throws IOException {
      Scanner scnr = new Scanner(System.in);
      String studentName;
      String studentID;
      String studentInfoFileName;
      FileInputStream studentInfoStream = null;
      Scanner studentInfoScanner = null;
      
      // Read the text file name from user
      studentInfoFileName = scnr.next();

      // Open the text file
      studentInfoStream = new FileInputStream(studentInfoFileName);
      studentInfoScanner = new Scanner(studentInfoStream);
      
      // Read search option from user. 0: findID(), 1: findName()
      int userChoice = scnr.nextInt();

      // FIXME: findID() and findName() may throw an Exception.
      //        Insert a try/catch statement to catch the exception and output the exception message.
      try {
      if (userChoice == 0) {
         studentName = scnr.next();
         studentID = findID(studentName, studentInfoScanner);
         System.out.println(studentID);
      }
      else {
         studentID = scnr.next();
         studentName = findName(studentID, studentInfoScanner);
         System.out.println(studentName);
      }
      
      studentInfoStream.close(); 
      
      }
      
      
      catch (Exception exp) {
          
        System.out.println(exp.getMessage());  
      }
      
      
      
   }
}

Answer 1

您需要从Scanner中读取每一行，并将字符串split()到一个包含2个值的数组中，然后进行比较。尝试以下代码：

public static String findID(String studentName, Scanner infoScnr) throws Exception {
    while (infoScnr.hasNextLine()) {
        String line = infoScnr.nextLine();
        String[] values = line.split(" ", 2);
        if (studentName != null && studentName.equals(values[0])) {
            return values[1];
        }
    }
    throw new Exception ("Student name not found for " + studentName);
}

public static String findName(String studentID, Scanner infoScnr) throws Exception {
    while (infoScnr.hasNextLine()) {
        String line = infoScnr.nextLine();
        String[] values = line.split(" ", 2);
        if (studentID != null && values.length > 1 && studentID.equals(values[1])) {
            return values[0];
        }
    }
    throw new Exception ("Student id not found for " + studentID);
}

Answer 2

.split (" ")

对于间距

.split ("/n")

用于新行(nextLine)