Regular expression: Replace everything before first occurence

user_14010822 0
Viewed 55

I have the following regular expression that I'm using to remove the dev. part of my URL.

String domain = "dev.mydomain.com";
System.out.println(domain.replaceAll(".*\\.(?=.*\\.)", ""));

Outputs: mydomain.com but this is giving me issues when the domains are in the vein of dev.mydomain.com.pe or dev.mydomain.com.uk in those cases I am getting only the .com.pe and .com.uk parts.

Is there a modifier I can use on my regex to make sure it only takes what is before the first . (dot included)?

Desired output:

dev.mydomain.com -> mydomain.com

stage.mydomain.com.pe -> mydomain.com.pe

test.mydomain.com.uk -> mydomain.com.uk

regex java
2 Answers

You may use

^[^.]+\.(?=.*\.)

See the regex demo and the regex graph:

enter image description here

Details

  • ^ - start of string
  • [^.]+ - 1 or more chars other than dots
  • \. - a dot
  • (?=.*\.) - followed with any 0 or more chars other than line break chars as many as possible and then a ..

Java usage example:

String result = domain.replaceFirst("^[^.]+\\.(?=.*\\.)", "");
user_38329700

Following regex will work for you. It will find first part (if exists), captures rest of the string as 2nd matching group and replaces the string with 2nd matching group. .*? is non-greedy search that will match until it sees first dot character.

(.*?\.)?(.*\..*)

Regex Demo

sample code:

String domain = "dev.mydomain.com";
System.out.println(domain.replaceAll("(.*?\\.)?(.*\\..*)", "$2"));

domain = "stage.mydomain.com.pe";
System.out.println(domain.replaceAll("(.*?\\.)?(.*\\..*)", "$2"));

domain = "test.mydomain.com.uk";
System.out.println(domain.replaceAll("(.*?\\.)?(.*\\..*)", "$2"));

domain = "mydomain.com";
System.out.println(domain.replaceAll("(.*?\\.)?(.*\\..*)", "$2"));

output:

mydomain.com
mydomain.com.pe
mydomain.com.uk
mydomain.com
user_139007480
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