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Java

Posted by Furquan Ahmad
Furquan Ahmad
5,148 Points

Java Regex expression

I'm trying to validate a filepath a user has entered. So they need to make sure it is in the format such as "C:/files/documents/hello.txt and they need to specify the file type at the end. The isFile method doesn't seem to satisfy this as the file hast to exist, so i'm trying to use regex now with an if statement. I know you need to add more slashes in java regex because of the escape sequence but i can't get it to work 

public class Main {
    public static void main (String [] args) throws FileNotFoundException {
            String fileName = "C:/users/furquan/hello.txt";
            File zerina = new File (fileName);
            //FileInputStream fis = new FileInputStream (zerina);
            String regex = "\\^(?:[\w]\:|\\\)(\\\[a-z_\-\s0-9\.]+)+\\\.(txt|gif|pdf|doc|docx|xls|xlsx)$";
            System.out.println (fileName.matches(regex));
        }

1 Answer

jcorum
jcorum
71,830 Points
jcorum
jcorum
71,830 Points

It might be easier if you do it in two steps. For the first step -- seeing if it is a valid path -- the Regex Library (http://www.regxlib.com) has over a dozen possible expressions. Hopefully one of those will do the job for you. Then, for the second step, you can check separately to see if the last three or four letters are in your set of possible file extensions: txt|gif|pdf|doc|docx|xls|xlsx.