How to check a string contains only digits and decimal points?

Question

For example I want to check that my when I split my string that the first part only contains numbers and decimal points.

I have done the following

Answer 1

You can simply add a dot to the list of allowed characters:

if(parts_s1[0].matches("[.0-9]+")

This, however, would match strings that are composed entirely of dots, or have sequences of multiple dots.