Question

So I have a regular expression to search for and be replaced by another regular expression in java. I am using grouping and was wondering if there was a way to make a group in the replacement optional.
For example, here is the regex i am searching for:

^(\d*).(\d)(\d?)$

could i do something like this for the replacement if the third group doesn’t exist:

$1$2$3?

Any help is greatly appreciated. Thank you

Answer 1

No, you can’t, but you don’t need to do this, either.

If the third group doesn’t match, $3 will be the empty string, so it won’t change the result of the replace operation.