java.io.File#toPath() on Windows doesn't understand "NUL:" (null device)?

[Alan Bateman]

On 17/03/2021 03:21, Jaikiran Pai wrote:
> :
>
>
> The code tries to read from NUL: on a Windows setup. This code runs 
> into the following exception on Windows when the java.io.File#toPath() 
> gets invoked:
>
>
> Exception in thread "main" java.nio.file.InvalidPathException: Illegal 
> char <:> at index 3: NUL:
>     at 
> java.base/sun.nio.fs.WindowsPathParser.normalize(WindowsPathParser.java:182)
>     at 
> java.base/sun.nio.fs.WindowsPathParser.parse(WindowsPathParser.java:153)
>     at 
> java.base/sun.nio.fs.WindowsPathParser.parse(WindowsPathParser.java:77)
>     at java.base/sun.nio.fs.WindowsPath.parse(WindowsPath.java:92)
>     at 
> java.base/sun.nio.fs.WindowsFileSystem.getPath(WindowsFileSystem.java:230)
>     at java.base/java.io.File.toPath(File.java:2316)
>     at FileTest.main(FileTest.java:18)
>
>
> So it looks like java.io.File.toPath() on Windows isn't able to 
> recognize the null device construct?

Special devices, esp. those historical devices from the DOS era, are 
very problematic.

NUL is somewhat benign compared to the other and you use "NUL" (not 
"NUL:") then should work as you expect. Changing the path parser to 
allow ":" in places other than after drive letters is a slippery slope 
as it brings all a lot of the issues that plagued the older code.

-Alan