使用条件按新行拆分字符串

Question

I am trying to split a String by \n only when it's not in my "action block".
Here is an example of a text message\n [testing](hover: actions!\nnew line!) more\nmessage I want to split when ever the \n is not inside the [](this \n should be ignored) , I made a regex for it that you can see here https://regex101.com/r/RpaQ2h/1/ in the example it seems like it's working correctly so I followed up with an implementation in Java:

final List<String> lines = new ArrayList<>();
final Matcher matcher = NEW_LINE_ACTION.matcher(message);

String rest = message;
int start = 0;
while (matcher.find()) {
    if (matcher.group("action") != null) continue;

    final String before = message.substring(start, matcher.start());
    if (!before.isEmpty()) lines.add(before.trim());

    start = matcher.end();
    rest = message.substring(start);
}

if (!rest.isEmpty()) lines.add(rest.trim());

return lines;

This should ignore any \n if they are inside the pattern showed above, however it never matches the "action" group, seems like when it is added to java and a \n is present it never matches it. I am a bit confused as to why, since it worked perfectly on the regex101.

Answer 1

Instead of checking whether the group is action , you can simply use regex replacement with the group $1 (the first capture group).

I also changed your regex to (?<action>\[[^\]]*]\([^)]*\))|(?<break>\\n) as [^\]]* doesn't backtrack ( .*? backtracks and causes more steps). I did the same with [^)]* .

See code working here

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {

    public static void main(String[] args) {

        final String regex = "(?<action>\\[[^\\]]*\\]\\([^)]*\\))|(?<break>\\\\n)";
        final String string = "message\\n [testing test](hover: actions!\\nnew line!) more\\nmessage";

        final Pattern pattern = Pattern.compile(regex);
        final Matcher matcher = pattern.matcher(string);

        final String result = matcher.replaceAll("$1");

        System.out.println(result);

    }

}