Regular Expression: Why do I get no match found

I am trying to parse a document that consists of many sections.

Each section begins with :[]: followed by blank space, followed by 1 or more characters (any characters), followed by a : a blank space and one or more characters (any characters).

Here's an example:

:[]: Abet1, Abetted34: Find the usage in table under section 1-CB-45: Or more info from the related section starting with PARTIE-DU-CORPS.
:[]: Ou est-ce que tu a mal: Tu as mal aux jambes: Find usage in section 145-TT-LA-TETE.

The token of interest from each section is everything from :[]: to the first occurrence of :. For example, in the first section, I am only interested in extracting: :[]: Abet1, Abetted34:

At first, I used the following pattern finder to extract the token from each section of the document but this extracted everything from the first occurrence of : to the last occurrence of : in the section:

"\\B:\\[\\]:.*:\\B"

If I change the pattern finder to the following to extract the token from :[]: to the first occurrence of :, I get no match:

"\\B:\\[\\]:\\s*.:{1}"

How would the regular expression that extracts what I want look like?

This is what you want?

See more : https://regex101.com/r/jOmnSb/2

Or

See more : https://regex101.com/r/jOmnSb/3

UPDATE :

You can convert regex to Java regex here : https://www.regexplanet.com/advanced/java/index.html

So you want to match a string against:

1. :[]:_ (where _ is a space character)
2. followed by one or more characters that are not a : (refer to this question)
3. close the match with a : character

The regex for that would be:

:\[\]: [^:]+:

You have to escape \ characters when converting the regex pattern to Java. You could do something like:

import java.util.regex.*; 
public class MatchTest {
    public static void main(String[] args) {
        Pattern pattern = Pattern.compile(":\\[\\]: [^:]+:", Pattern.CASE_INSENSITIVE);
        Matcher matcher =
            pattern.matcher(
                ":[]: Abet1, Abetted34: Find the usage in table under section 1-CB-45: Or more info from the related section starting with PARTIE-DU-CORPS.\n"
              + ":[]: Ou est-ce que tu a mal: Tu as mal aux jambes: Find usage in section 145-TT-LA-TETE."
            );
        while (matcher.find()) {
            System.out.println(matcher.group());
        }
    }
}