How to get the file extension in grails? - 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?

Answer 1

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'
}

Answer 2

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 (<?\.)

Answer 3

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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