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From: Andreas Leitgeb <avl@logic.at>
Newsgroups: comp.lang.java.programmer
Subject: Re: regex replaceAll?
Date: Thu, 1 Mar 2018 19:03:34 -0000 (UTC)
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Eric Douglas <e.d.programmer@gmail.com> wrote:
> I hate to ask because I feel like I'm close and missing something stupid, but how do you do this?
> String in = "abc aa bb cc a bb ccc   a b c abc aa bbb cc babacaca";
> I've found we can replace every third space using this:
> String out;
>  out = in.replaceAll("(?<=\\G\\S*\\s\\S*\\s\\S*)\\s", "_");
> System.out.println(out);
> Result:
> "abc aa bb_cc a bb_ccc  _a b c_abc aa bbb_cc babacaca"
>
> Now I'm trying to replace the nth occurrence of a string.
> The best I can find matches the nth sequential.
>
> int n = 2;
> String repl = "b";
>  out = in.replaceAll("([.]*["+repl+"]{"+(n-1)+"}[.]*)"+repl,"$1_");

[.] only matches a literal dot. That might be the root-cause of why it's
not working the way you like.

> System.out.println(out);
>
> Result:
> "abc aa b_ cc a b_ ccc   a b c abc aa b_b cc babacaca"
>
> What I'm looking for:
> "abc aa _b cc a _b ccc   a _ c abc aa _b_ cc ba_acaca"