java - 使用 BufferedReader 读取行

Question

我正在尝试从文件中读取信息来解释它。我想读取每一行输入。我最近刚刚了解了 bufferedreader。然而，我的代码的问题是它跳过了每隔一行。

例如，当我输入8行数据时，它只打印其中的4行。偶数者。

这是代码:

import java.io.*;
import java.util.Scanner;

public class ExamAnalysis
{
  public static void main(String[] args) throws FileNotFoundException, IOException
  {

    int numOfQ = 10;

    System.out.println();
    System.out.println("Welcome to Exam Analysis.  Let’s begin ...");
    System.out.println();
    System.out.println();

    System.out.println("Please type the correct answers to the exam     questions,");
    System.out.print("one right after the other: ");
    Scanner scan = new Scanner(System.in);
    String answers = scan.nextLine();

    System.out.println("What is the name of the file containing each student's");
    System.out.print("responses to the " + numOfQ + " questions? ");
    String f = scan.nextLine();
    System.out.println();

    BufferedReader in = new BufferedReader(new FileReader(new File(f)));
    int numOfStudent= 0;

    while ( in.readLine() != null )
    {
      numOfStudent++;
      System.out.println("Student #" + numOfStudent+ "\'s responses: " + in.readLine());
    }
    System.out.println("We have reached “end of file!”");             
    System.out.println();
    System.out.println("Thank you for the data on " + numOfStudent+ " students. Here is the analysis:");
   }
 }
 }

我知道这可能是有点糟糕的写作风格。我对编码真的很陌生。因此，如果有任何方法可以帮助我修复代码和方法的风格，我会非常兴奋。

该程序的重​​点是将答案与正确答案进行比较。因此我还有另一个问题:

如何将字符串与缓冲读取器进行比较？就像我如何将 ABCCED 与 ABBBDE 进行比较，以查看前两个匹配但其余的不匹配。

谢谢

Answer 1

the problem with my code is that it skips every other line

您的 EOF 检查在每次迭代时都会抛出一行

while ( in.readLine() != null ) // read (first) line and ignore it
{
  numOfStudent++;
  System.out.println("Student #" + numOfStudent+ "\'s responses: " + 
    in.readLine());   // read (second) next line and print it
}

要读取所有行，请执行以下操作:

String line = null;
while ( null != (line = in.readLine())) // read line and save it, also check for EOF
{
  numOfStudent++;
  System.out.println("Student #" + numOfStudent+ "\'s responses: " + 
    line);   // print it
}

要比较字符串，您需要使用 String#compareTo(String other)方法。如果返回值为 0，则两个字符串相等。