regex - Regular expression for path validation? -

i have path , need write regular expression filter path common-io library.

the path should not contain:

• req/com/res,
• res/com/req,
• req/al/res,
• res/al/req,
• _svn

and path should end .xml.

 fileutils.listfiles(afile, new regexfilefilter("^(.*?)"), truefilefilter.instance) 

if this, returns xmls.

i don't have idea regex; please give idea how this?

you can use following regex:

^(?i)(?!.*(?:re[qs]/(?:com|al)/re[sq]|_svn)).*\\.xml$ 

see demo

the (?i) pattern makes case-insensitive. remove if want make search case-sensitive. (?!.*(?:re[qs]/(?:com|al)/re[sq]|_svn)) pattern makes sure not allow of forbidden strings inside path.

if want account whole words, add \b:

^(?i)(?!.*\\b(?:re[qs]/(?:com|al)/re[sq]|_svn)\\b).*\\.xml$ 

see another demo

note in java-style regex not need escape / , have double-escape special characters.