Java Matcher Pattern issue

Question

I am trying to extract everything that is after this string path /share/attachments/docs/. All my strings are starting with /share/attachments/docs/

For example: /share/attachments/docs/image2.png Number of characters after ../docs/ is not static!

I tried with

   Pattern p = Pattern.compile("^(.*)/share/attachments/docs/(\\d+)$");
   Matcher m = p.matcher("/share/attachments/docs/image2.png");
   m.find();         
   String link = m.group(2);    
   System.out.println("Link #: "+link);

But I am getting Exception that: No match found. Strange because if I use this:

   Pattern p = Pattern.compile("^(.*)ABC Results for draw no (\\d+)$");
   Matcher m = p.matcher("ABC Results for draw no 2888");

then it works!!!

Also one thing is that in some very rare cases my string does not start with /share/attachments/docs/ and then I should not parse anything but that is not related directly to the issue, but it will be good to handle.

Answer 1

I am getting Exception that: No match found.

This is because image2.png doesn't match with \d+ use a more appropriate pattern like .+ assuming that you want to extract image2.png.

Your regular expression will then be ^(.*)/share/attachments/docs/(.+)$

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In case of ABC Results for draw no 2888, the regexp ^(.*)ABC Results for draw no (\\d+)$ works because you have several successive digits at the end of your String while in the first case you had image2.png that is a mix of letters and digits which is the reason why there were no match found.

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Generally speaking to avoid getting an IllegalStateException: No match found, you need first to check the result of find(), if it returns true the input String matches:

if (m.find()) {
   // The String matches with the pattern
   String link = m.group(2);    
   System.out.println("Draw #: "+link);
}  else {
   System.out.println("Input value doesn't match with the pattern");
}