Question

I’m trying to extract strings from a text that features two different types of characters.
The characters are | and # and the text is coming from an outside source.

I will give you an example:

• Input: #hello|#what|whatsup| should return hello| and whatsup.
• Input: #hello# should return hello
• Input: |ola|1 should return ola
• Input: |hello#|what#whatsup#node should return hello# and whatsup

Answer 1

This works for your strings. I don’t know if I completely understood what you need, but I think it can be tuned if necessary:

     String s1 = "#hello|#what|whatsup|";
     String s2 = "#hello#";
     String s3 = "|ola|1";
     String s4 = "|hello#|what#whatsup#node";

     Pattern pattern = Pattern.compile("((\\w)+)(\\||#)(\\||#)?");
     Matcher matcher = pattern.matcher(s4);
     while(matcher.find()) {
         System.out.println(matcher.group(1) + (matcher.group(4) != null ? matcher.group(4).equals("|")? "#" : "|" : ""));
         matcher.find(); //to jump over the next match
     }

Update:
I just read the middlerecursion example. Doesn’t work for that, I’m afraid, and I have to leave my computer for a while. So this is just something to get you started.

Update version that works for all the examples:

     String s1 = "#hello|#what|whatsup|";
     String s2 = "#hello#";
     String s3 = "|ola|1";
     String s4 = "|hello#|what#whatsup#node";
     String s5 = "#||##||MiddleRecursion||##||#";

     Pattern pattern = Pattern.compile("(#|\\|)((#|\\|)*\\w+(#|\\|)*)(#|\\|)");
     Matcher matcher = pattern.matcher(s1);
     while(matcher.find()) {
         System.out.println(matcher.group(2));
     }