Java IO给我一个错误

Question

当我运行下面的代码时，我得到一个错误。

package practicing.io;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class JavaIO {
  public static void main(String[] args) throws IOException {
    FileInputStream in = null;
    FileOutputStream out = null;
    try {
        in = new FileInputStream("xanaduout.txt");
        out = new FileOutputStream("out.txt");
        int c;

        while ((c = in.read()) != -1) {
            out.write(c);
        }

    } finally {
        if (in != null) {
            in.close();
        }
        if (out != null) {
            out.close();
        }
    }
   }
}

这是直接从Sun的在线教程中摘录的。请告诉我出什么事了。

Answer 1

"xanaduout.txt“是否存在？在您当前的目录中？

如果不是，您可以始终对路径进行硬编码。但这不是好的做法:)

在任何情况下，该错误都会准确地说明所发生的情况:您正在尝试打开一个文件...系统找不到它。

Answer 2

给出文件的确切位置。

你应该试试

   in = new FileInputStream("c:\xanaduout.txt");

而不是这个

   in = new FileInputStream("xanaduout.txt");

Answer 3

错误消息显示：

Exception in thread "main" java.io.FileNotFoundException: xanaduout.txt 
(The system cannot find the file specified)

并且似乎源自您代码的第12行：

at practicing.io.JavaIO.main(JavaIO.java:12)

代码的第12行是：

in = new FileInputStream("xanaduout.txt");

因此，您正在尝试从文件xanaduout.txt读取，而Java抱怨它找不到该文件。

编辑

@Keith Mattix编辑您的程序以打印出它正在读取的文件的路径，并验证该文件是否确实存在于磁盘上：

public class JavaIO {
  public static void main(String[] args) throws IOException {
    FileInputStream in = null;
    FileOutputStream out = null;
    try {
        File file = new File("xanaduout.txt");
        System.out.println("My program is going to read the file " +
            file.getCanonicalPath() + " which " + (file.exists()? "" : "does not") +
            " exist on disk"); 
        in = new FileInputStream(file);
        out = new FileOutputStream("out.txt");
        int c;

        while ((c = in.read()) != -1) {
            out.write(c);
        }

    } finally {
        if (in != null) {
            in.close();
        }
        if (out != null) {
            out.close();
        }
    }
   }
}