How to get the file extension in grails?

Question

I recently started working on grails and i want to know how to get the extension of a file. Ex: test.txt. I want to check extension(txt)? any clue?

See http://stackoverflow.com/questions/5019478/grails-file-upload-how-to-recognize-file-and-or-content-type — Mihai8, Oct 02 '15 at 22:41
Please dont mind. What exactly the contentType will return ? is it same as mediaType. Like mediaType will return text/plain for .txt file and the same will return for xml json. — DirtyMind, Oct 02 '15 at 22:46
Possible duplicate of [How do I get the file extension of a file in Java?](http://stackoverflow.com/questions/3571223/how-do-i-get-the-file-extension-of-a-file-in-java) — cfrick, Oct 03 '15 at 09:34

score 4 · Accepted Answer · answered Oct 03 '15 at 00:10

4

Here's another way. Using a regular expression.

def fileName = 'something.ext'
def matcher = (fileName =~ /.*\.(.*)$/)

if(matcher.matches()) {
    def extension = matcher[0][1]

    if(extension in ['jpg', 'jpeg', 'png']) {
        // Good to go
        println 'ok'
    } else {
        println 'not ok'
    }
} else {
    println 'No file extension found'
}

answered Oct 03 '15 at 00:10

Emmanuel Rosa

9,697
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will this regEx work for .doc .docx .pdf .xlsx .xls .txt ?? – DirtyMind Oct 03 '15 at 00:40
Yes. The regex boils down to: everything after the last period. So it can handle file extensions of arbitrary length. Just add them to the list. – Emmanuel Rosa Oct 03 '15 at 01:43

score 1 · Answer 2 · answered Jul 21 '19 at 00:38

The question asks how to get the file extension.

With groovy, the following operation will give you the file extension of any file name:

def fileName = ...
def fileExt = fileName - ~/.*(?<=\.)/

The accepted answer goes a bit further and tries to check for specific file extensions. You can use the match operator ==~ to do this as well:

assert fileName ==~ ~/.*(?<=\.)(txt|jpe?g|png)/

This assertion will work provided the file name ends with one of the supplied extensions.

^{Also noticed that groovy can do positive lookbehind using (<?\.)}

score 0 · Answer 3 · edited May 23 '17 at 12:33

Hope i found the answer of my Question. How to find the extension of a file.

String fileName = "something.ext";
        int a = fileName.lastIndexOf(".");
        String extName = fileName.substring(a);
        System.out.println(fileName.substring(a));
        ArrayList<String> extList = new ArrayList<String>();
        extList.add("jpg");
        extList.add("jpeg");
        extList.add("png");
        if(extList.contains(extName))
        {
            System.out.println("proceed");
        }
        else{
            System.out.println("throw exception");
        }

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How to get the file extension in grails?

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