Question

I have a regex that will validate to make sure I have a number. but it passed if the string I’m checking is “” as well. how can I make a “” fail?

^(\\d|-)?(\\d|,)*\\.?\\d*$

Answer 1

You could require at least one digit:

^-?\d[\d,]*(?:\.\d+)?$
   ^^
required

Rubular

To also allow matching .05:

^-?\d[\d,]*(?:\.\d+)?$|^-?\.\d+$

Rubular

Note that your expression also allows multiple commas one after another which may not be desirable.