Local final variable or member?

Hello!

Hope to get some comment about this.

I use PMD to check my code as often as I can.

Consider this method:

    public boolean isDir() {
        File file = new File(filePath);
        return (file.isDirectory());
    }

PMD gives this comment:
Local variable 'file' could be declared final

If I do that like:

    public boolean isDir() {
        final File file = new File(filePath);
        return (file.isDirectory());
    }

Then I get this comment from PMD:
Avoid using final local variables, turn them into fields

Seems like there is a contradiction in PMD?
In this particularly case there is no use for making "file" into a field.
So is there any case when I should set local variables final?

What do you guys prefer?

Best regards
Fredrik