Java regex plus at the beginning is optional

Question

I would like to write Java regex where plus at the beginning is optional

I try this but not working correctly

[+]+[0-9]{3,}

so that +123 and 123 is valid

What I am doing wrong?

Answer 1

As Hamza commented below, use [+]?[0-9]{3,}. A question mark means one or none of the previous, which in this case means one or no + before the three numbers.