该程序既不读取也不写入文件

发布于 2024-12-12 06:34:57 字数 589 浏览 0 评论 0原文

代码

import java.io.*;
class tester {
 public static void main(String args[]) {
  try {
   FileReader reader = new FileReader(new File("d:\\UnderTest\\check123.txt"));
   FileWriter writer = new FileWriter(new File("d:\\UnderTest\\check123.txt"));
   BufferedReader br = new BufferedReader(reader);
   String s;
     while( (s=br.readLine()) != null ) {
       System.out.println(s);
     }
   writer.write("Shadow Shadow");
  } catch(Exception exc) {
     System.out.println(exc);
    }
  }
}

当我运行它时，该代码不写入任何内容，也不读取任何内容。这个程序的bug在哪里？

原文

CODE

import java.io.*;
class tester {
 public static void main(String args[]) {
  try {
   FileReader reader = new FileReader(new File("d:\\UnderTest\\check123.txt"));
   FileWriter writer = new FileWriter(new File("d:\\UnderTest\\check123.txt"));
   BufferedReader br = new BufferedReader(reader);
   String s;
     while( (s=br.readLine()) != null ) {
       System.out.println(s);
     }
   writer.write("Shadow Shadow");
  } catch(Exception exc) {
     System.out.println(exc);
    }
  }
}

This code writes nothing and reads nothing when i run it. Where is the bug in this program ?

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泪冰清 2024-12-19 06:34:57

您确定当您第一次阅读时文本文件中存在内容吗？
您需要在 try-catch 块的 finally 块（当前代码中缺少）中关闭 Reader 和 Writer。关闭流会自动刷新内容。

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风追烟花雨 2024-12-19 06:34:57

确保关闭读者和作者。使用写入器后，您将需要刷新内容或关闭写入器（执行相同的操作）。我测试了这个并且它有效。

import java.io.*;
class tester {
 public static void main(String args[]) {
  try {
  FileReader reader = new FileReader(new File("c:\\check123.txt"));
  FileWriter writer = new FileWriter(new File("c:\\check123.txt"));
  BufferedReader br = new BufferedReader(reader);
  writer.write("Shadow Shadow");     
  writer.close();

  String s;
    while( (s=br.readLine()) != null ) {
      System.out.println(s);
    }
  reader.close();

 } catch(Exception exc) {
    System.out.println(exc);
   }
}

}

Make sure you close the reader and the writer. After using the writer you will need to flush the contents or close the writer (which does the same thing). I tested this and it works.

import java.io.*;
class tester {
 public static void main(String args[]) {
  try {
  FileReader reader = new FileReader(new File("c:\\check123.txt"));
  FileWriter writer = new FileWriter(new File("c:\\check123.txt"));
  BufferedReader br = new BufferedReader(reader);
  writer.write("Shadow Shadow");     
  writer.close();

  String s;
    while( (s=br.readLine()) != null ) {
      System.out.println(s);
    }
  reader.close();

 } catch(Exception exc) {
    System.out.println(exc);
   }
}

}

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