Regex to use in replaceall

[Ram ank]

Hi Guys

I want to add newline after occurence of IPV4 address in my string. I am trying with output.replaceAll("?<=(\\d{1,3}\\.){3}\\d{1,3}", "\n");
But it is throwing Exception. Please help me.

[Jeff Verdegan]

Ram ank wrote:But it is throwing Exception. Please help me.

You need to TellTheDetails(⇐click)

Copy/paste the exact, complete error message, as well as the line of code that caused it.

[Jeff Verdegan]

One thing jumps out at me though. As far as I know, you have to do

"(?<=X)"

not just

"?<=X"

[Ram ank]

It worked like this
with ?<ip> it stores the matching string and using it in replacement with ${ip}

output.replaceAll("(?<ip>(\\d{1,3}\\.){3}\\d{1,3})", "${ip}\n");

Thank you guys