Compilation of Regex in Apex

Question

I am trying to compile following regex

/^[~`!@#$%^&*()_+=[]{}|;':",./<>?a-zA-Z0-9-\w\s]+$/

String fileNameRegex = '/^\[~`!@#$%^&*()_+=\[\]\{}|;':",.\/<>?a-zA-Z0-9-\w\s\]+$/';
Pattern FileNamePattern = Pattern.compile(fileNameRegex);
String testString = '世界tes';
Matcher FileNameMatcher = FileNamePattern.matcher(testString);
 
if(FileNameMatcher.matches())
{
   system.debug('***true**');
}
else{
   system.debug('***false**');
}

I did escape special charters with '\' , please advise.

\/\^\[~`\!@\#\$%\^&\*\(\)_\+\=\[\\\]\\\{\}\|;'\:",\.\\\/\<\>\?a\-zA\-Z0\-9\-\\w\\s\]\+\$\/

Answer 1

The simple answer, as already stated in the comments, is that you need to use double-backslashes to escape things in regex in Apex.

So insted of

String fileNameRegex = '/^\[~`!@#$%^&*()_+=\[\]\{}|;':",.\/<>?a-zA-Z0-9-\w\s\]+$/';

You'd need

String fileNameRegex = '^[~`!@#$%^&*()_+=\\[\\]\\{\\}\\|;\':",.\\\\/<>?a-zA-Z0-9-\\w\\s]+$';

Note that in addition to the doubling of backslashes, I also:

• Escaped the single quote in (what I'm assuming is) your character class that you're trying to build, but only once (since it is a valid escape sequence outside of regex)
• Escaped the pipe and closing curly brace
• Unescaped the square braces near the start and end
• Getting a literal backslash character requires 4 total backslashes in Apex
• The leading and trailing / are removed (they aren't needed, and in fact make your regex non-functional)

That is sufficient to get this to run (though not necessarily produce the desired result).

It looks to me like you're attempting to detect printable ASCII characters. If that is the case, then you can make your life a whole lot simpler by using POSIX Character Classes.

i.e. String fileNameRegex = '^\\p{Print}+$';