[Solved] Regular Expressions in Java replace odd # of slashes

by 


  Pattern p = Pattern.compile("(?<!/)/(//)*(?!/)");
  Matcher m = p.matcher(inputString);
  String outputStr = m.replaceAll("$0$0");
  • (?<!/) makes sure there are no slashes right before the match;
  • /(//)* matches an odd number of slashes;
  • (?!/) makes sure there are no slashes right after the match.

The replacement string is $0$0, which doubles up the matched slashes.

I’ve tested this on your inputs, and it works exactly as per your spec.

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solved Regular Expressions in Java replace odd # of slashes