带有try块的Java BufferedReader错误

问题描述

我有一种应该加载文件的方法，但是它给了我这个错误：

I have this method that is supposed to load a file but it is giving me this error:

NamnMetod.java:175: error: unreported exception FileNotFoundException; must be caught or declared to be thrown
                 BufferedReader inFil = new BufferedReader(new FileReader(fil));
                                                           ^
NamnMetod.java:177: error: unreported exception IOException; must be    caught or declared to be thrown
                 String rad = inFil.readLine();  
                                            ^

这是我的代码：

   public static void hämtaFrånText() {
    try {
     EventQueue.invokeAndWait(new Runnable() {
     @Override

        public void run() {
              String aktuellMapp = System.getProperty("user.dir");
           JFileChooser fc = new JFileChooser(aktuellMapp);
           int resultat = fc.showOpenDialog(null);

              if (resultat != JFileChooser.APPROVE_OPTION) {
                 JOptionPane.showMessageDialog(null, "Ingen fil valdes!");
                 System.exit(0);
              }
                 String fil = fc.getSelectedFile().getAbsolutePath();
                 String[] namn = new String[3];         
                 String output ="";         
                 BufferedReader inFil = new BufferedReader(new FileReader(fil));                    
                 String rad = inFil.readLine();

                 int antal = 0;

                    while(rad != null){                  
                        namn[antal] = rad;
                        rad = inFil.readLine();
                        antal++;
                    }
                    inFil.close();

       }
    });                     
    }catch(IOException e2) {        
        JOptionPane.showMessageDialog(null,"The file was not found!");
    }           
}

我很困惑，因为我同时捕获了IOException和FileNotFoundException，但我仍然收到此错误...

I'm perplexed because i have caught both IOException and FileNotFoundException but I still get this error...

推荐答案

您在创建的代码中捕获了它们 Runnable ，而需要在 Runnable.run（）中捕获异常。

You are catching them in the code which creates the Runnable, whereas the exceptions need to be caught in Runnable.run().

在您的 run 方法内移动try / catch。

Move the try/catch inside your run method.

另外，使用try-with-resources来确保FileReader始终关闭，即使发生异常也是如此：

Also, use try-with-resources to ensure that the FileReader is always closed, even if an exception occurs:

try (FileReader fr = new FileReader(fil);
     BufferedReader inFil = new BufferedReader(fr)) {
  // ...

  // No need to close `fr` or `inFil` explicitly.
}

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