Retrieving the underlying error when File.listFiles return null.

Question

According to the File.listFiles javadoc the method

Returns null if this abstract pathname does not denote a directory, or if an I/O error occurs.

I know that I am using a directory, but have received a null result, so an I/O error must've appeared. I'm very much interested in what the error was.

How can I retrieve the error message/code when such a null result is returned?

Answer 1

From what I see from an implementation of File, it will return null if

• the file is not a directory or
• the file does not exist or
• the directory is read-protected.

No evidence of a 'hidden' IOException although an I/O Error might occur in the native code.

Answer 2

How likely is it that an I/O error occurs every time you try to test your code? I would say that there is a problem with the directory not existing or you not having the right permissions.