java - 使用 FileReader 时解决 IOException、FileNotFoundException

Question

我无法解决以下代码中的以下异常。我使用 BufferedReader 的方式有什么问题？我在 main 方法中使用 BufferedReader

输出:-

ParseFileName.java:56: unreported exception java.io.FileNotFoundException; must be caught or declared to be thrown 

BufferedReader buffread = new BufferedReader (new FileReader("file.txt"));

---

// ParseFileName  is used to get the file name from a file path 
// For eg: get  - crc.v  from "$ROOT/rtl/..path/crc.v"

import java.util.regex.Pattern;
import java.io.*;

public class ParseFileName { 

  //Split along /'s , and collect the last term. 
  public String getName (String longName) { 
      String splitAt = "/";
      Pattern pattern1 = Pattern.compile(splitAt);
      String[] parts  = pattern1.split(longName);
      System.out.println("\nparts.length =  " + parts.length);

      //Return the last element in the array of strings 
      return parts[parts.length -1]; 
  }

  public static void main(String[] args) { 
    ParseFileName  superParse = new ParseFileName();  
    BufferedReader buffread = new BufferedReader (new FileReader("file.txt"));
    String line;
    while ((line = buffread.readLine())!= null) {
        String fileName = superParse.getName(line);
        System.out.println("\n" + line + "  =>  " + fileName);
    }
    buffread.close();

  }

}

更新:以下作品:

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

但是 try..catch 仍然有一些困扰我的问题:

try {
BufferedReader buffread = new BufferedReader (new FileReader("file.txt"));
} catch (FileNotFoundException ex) {
    ex.printStackTrace();
} catch (IOException ex2) {
   ex2.printStackTrace();
}

buffread dosent 好像是得到了文件名。我收到此错误:

javac ParseFileName.java ParseFileName.java:67: cannot resolve symbol

符号:变量 buffread

location: class ParseFileName

while ((line = buffread.readLine())!= null) {

Answer 1

在方法的 header 中添加 throws FileNotFoundException, IOException。看起来只要抛出 IOException 就可以解决您的问题，但是将两者结合起来可以让您判断文件的存在是否存在问题，或者是否出现了其他问题(请参阅下面的 catch 语句)。

即

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

或者，如果您想捕获一个特定的异常并对其进行处理:

try {
    BufferedReader buffread = new BufferedReader (new FileReader("file.txt"));
} catch (FileNotFoundException ex) {
    // Do something with 'ex'
} catch (IOException ex2) {
    // Do something with 'ex2'
}

更新以解决更新后的问题:这只是一个简单的范围问题，可以通过在 try 语句之外声明 BufferedReader 来解决。

BufferedReader buffread = null;
try {
    buffread = new BufferedReader (new FileReader("file.txt"));
} catch (FileNotFoundException ex) {
        ...