java - 为什么我无法捕获此 FileNotFoundException？

Question

package test4;

import java.io.*;

public class Reader {

    public static void main(String[] args) {
        print(send("test.txt"));
    }

    public static BufferedReader send(String filename) {
        File file = null;
        FileReader filer = null;
        BufferedReader filed = null;

        try {
            file = new File(filename);
        } catch(FileNotFoundException e) {
            System.err.println("Could not find file!");
        }

        try {
            filer = new FileReader(file);
        } catch(Exception e) {
            System.err.println("Could not initialize file reader!");
        }

        try {
            filed = new BufferedReader(filer);
        } catch(Exception e) {
            System.err.println("Could not initialize buffered reader!");
        }

        return filed;
    }
}

send 方法返回 null BufferedReader，因为找不到文件。 Eclipse 只是说由于 print 方法而存在 NullPointerException，但是当我删除所有 try/catch 语句时，Eclipse 说我需要编写该方法抛出 IOException 或 FileNotFoundException，它也允许我这样做，如果我否则它会抛出 FileNotFoundException。但是，当我 try catch 文件的 FileNotFoundException 时，Eclipse 说这是无法访问的代码？基本上这个位在这里:

    try {
        file = new File(filename);
    } catch(FileNotFoundException e) {
        System.err.println("Could not find file!");
    }

当仅删除 try/catch 语句允许我抛出 FileNotFoundException 时，为什么 Eclipse 会说此代码无法访问？

Answer 1

文件的构造函数不会抛出 FileNotFoundException，您可以在 Javadoc 处看到它。 :

public File(String pathname)

Creates a new File instance by converting the given pathname string into an abstract pathname. If the given string is the empty string, then the result is the empty abstract pathname.

Parameters: pathname - A pathname string

Throws:NullPointerException - If the pathname argument is null

但是 FileReader 抛出异常!再次，另一个javadoc

public FileReader(File file) throws FileNotFoundException Creates a new FileReader, given the File to read from.

Parameters: file - the File to read from

Throws: FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.