How to check file extension on Android

I would get the file name as a String, split it into an array with "." as the delimiter, and then get the last index of the array, which would be the file extension. For example:

public class main {
    public static void main(String[] args) {
        String filename = "image.jpg";
        String filenameArray[] = filename.split("\\.");
        String extension = filenameArray[filenameArray.length-1];
        System.out.println(extension);
    }
}

Which outputs:

jpg

public static String getFileExt(String fileName) {
    return fileName.substring(fileName.lastIndexOf(".") + 1, fileName.length());
}