Сколько же в каждой малюсенькой задаче сидит огромных...

How many huge questions are sitting in every tiny task. I never cease to be surprised at this famous truth. I make a field for entering a mask for selecting the displayed files (well, you know exactly what I mean, for example, * .txt). Clearly, you need to use the powerful standard regex engine in Java, but the syntax is different, more powerful. Everyone knows that in the * .txt entry, an asterisk means "any number of any characters", and in Java, an asterisk means repeating the characters before it, for example, a * means any number of letters a. But this is not a problem - now, I think, I’ll write a parser from one notation to another, but first we need to clarify the specification of simple expressions like * .txt - and that’s where it started.

First of all, for me, who knew little about the Unix system, it was news that these regular expressions are called glob (from the global command).

Now the main thing. The entry *. * Means any name and any extension, but if you approach formally, then this is any extension name containing a period! That is, files without an extension do not get here. Now open your favorite Norton-style file manager (checked on Total Commander and Far), click the gray plus, leave the default *. * Entered there and press enter. All files will be highlighted, including those that do not have an extension. There is no justice in the world.