Question

当我运行以下代码时，出现错误。

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();
        }
    }
   }
}

这是从Sun的在线教程中获得的。请告诉我出了什么问题。

Answer 1

提供文件的确切位置。

你应该试试

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

而不是这个

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

Answer 2

“xanaduout.txt”是否存在？在您当前的目录中？

如果没有，您可以随时对路径进行硬编码。但这不是好的做法：）

在任何情况下，错误都说明发生了什么：您正在尝试打开文件......系统无法找到它。

Answer 3

错误消息显示：

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

似乎源自代码的第12行：

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

代码的第12行是：

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

所以你试图从文件xanaduout.txt中读取而Java正在抱怨它无法找到该文件。

修改

@Keith Mattix编辑您的程序以打印出它正在读取的文件的路径，并确认该文件确实存在于磁盘上：

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(); } } } }

Java IO给了我一个错误

3 个答案: