Rewrite this regexp to match only when other char is present

Question

I have this regexp

Pattern pattern = Pattern.compile("\\{([^\\}]+)\\}");

to match {a1|a2|a3} and {a4} format

How can I rewrite the above line, to include those matches only when a pipe | is present, so to match {a1|a2|a3} and do not match on {a4}

Answer 1

Add a pipe character to your regular expression:

"\\{([^\\}]+\\|[^\\}]+)\\}"