分割分隔符java

Question

i've found an answer when searching in stackoverflow, it works perfectly but when i saw the comment the user doesn't explain how the code works, can someone explain to me how does this code means?....

String input =
      "        [John, 8, 9, 10, \r\n"
    + "       , Peter, 10, 8, 7, \r\n"
    + "       , Steve, 8, 9, 6, \r\n"
    + "         ]";
String output = input.replaceAll("(?m)^[\\s,\\[]+|[\\s,\\]]+$|[\\s&&[^\r\n]]+", "");
System.out.println(output);

Answer 1

Answering your question from the comment:

"[\\s&&[^\\r\\n]]+" this the part i dont understand at all, i don't get where the comma disappear while the is nocomma delimiter, and only bracket delimter" – Jansen Stanlie

I will ignore the string escapes and write it as true regex. In the java flavor of regex you can do class intersections and subtractions by using:

[..&&[..]] and [..&&[^..] respectively. Replace .. with your character class and inclusion/exclusion range.

For instance

[az&&[^aeiou]] would give you an english lowercase letter that is not a vowel.

So, in your example (removing java string escape) [\\s&&[^\\r\\n]] - \\s any whitespace character, except \\r or \\n. This was done to get rid of all spaces but keep the line breaks.

This could also be written as [\\s&&[\\V]] which would make it Unicode compliant. \\V is any character that is NOT a vertical whitespace.

The question about where the comma is removed: The leading comma is removed here:

(?m)^[\\s,\\[]+|[\\s,\\]]+$|[\\s&&[^\r\n]]+
         ^

and trailing:

(?m)^[\\s,\\[]+|[\\s,\\]]+$|[\\s&&[^\r\n]]+
                    ^