Java REGEX, remove two different type of comments from String

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I have a text with two types of comments. The ones delimited by % and the ones that start with /* and end with */. For instance:

INPUT1: Sarah was going out. % Remember she usually doesn't go out % It was very cold.

DESIRED_OUTPUT1: Sarah was going out. It was very cold.

INPUT2: Sarah was going out. /* Remember she usually doesn't go out */ It was very cold.

DESIRED_OUTPUT2: Sarah was going out. It was very cold.

INPUT3: Charles knocked on the door and a woman opened it. % Hmm, is this good... /* Not sure */ Perhaps this should happen in chapter 10 instead? % She looked at him. - Yes?, she said.

DESIRED_OUTPUT3: Charles knocked on the door and a woman opened it. She looked at him. - Yes?, she said.

INPUT4: Charles knocked on the door and a woman opened it. % Hmm, is this good... /* Not sure to 100% */ Perhaps this should happen in chapter 10 instead? % She looked at him. - Yes?, she said.

DESIRED_OUTPUT4: Charles knocked on the door and a woman opened it. */ Perhaps this should happen in chapter 10 instead?

Basically, I would like that when encountering an opening comment mark, everything is removed until its respective closing comment mark (even if this means removing comment marks of the other type).

If a comment is opened, either with % or /*, but never closed, the comment is assumed to continue until the end of the text. However, if it is present just a closing mark of this kind */ (because the opener was inside another comment and hence removed), it should be left in the text.

replace regex java
1 Answers

You may use

.replaceAll("%[^%]*%?|/\\*[^*]*(?:\\*(?!/)[^*]*)*(?:\\*/)?","")

See the regex demo

Details

  • %[^%]*%? - %...% like comments with an optional trailing delimiter:
    • % - a % char
    • [^%]* - 0 or more chars other than %
    • %? - an optional % char
  • | - or
  • /\*[^*]*(?:\*(?!/)[^*]*)*(?:\*/)? - /*...*/ like comments with an optional trailing delimiter:
    • /\* - /* string
    • [^*]* - 0 or more chars other than *
    • (?:\*(?!/)[^*]*)* - 0 or more occurrences of
      • \*(?!/) - a * not followed with /
      • [^*]* - 0 or more chars other than *
    • (?:\*/)? - an optional */ substring.
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