List of all special characters that need to be escaped in a regex

I am trying to create an application that matches a message template with a message that a user is trying to send. I am using Java regex for matching the message. The template/message may contain special characters.

How would I get the complete list of special characters that need to be escaped in order for my regex to work and match in the maximum possible cases?

Is there a universal solution for escaping all special characters in Java regex?

Solution 1:

You can look at the javadoc of the Pattern class: http://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html

You need to escape any char listed there if you want the regular char and not the special meaning.

As a maybe simpler solution, you can put the template between \Q and \E - everything between them is considered as escaped.

Solution 2:

• Java characters that have to be escaped in regular expressions are:
  \.[]{}()<>*+-=!?^$|
• Two of the closing brackets (] and }) are only need to be escaped after opening the same type of bracket.
• In []-brackets some characters (like + and -) do sometimes work without escape.