Simple java class to get file extension

ExtensionChecker.java

/**
 * Simple java class to get file extension.
 * Returns null if file starts with point, like .htaccess, and if the file don't have any extension.
 * Created by Sergio Marchenko on 05-05-2017.
 */
public class ExtensionChecker {
    public static String getFileExtension(String fileName) {
        if (!fileName.startsWith(".") && fileName.contains(".")) {
            return fileName.substring(fileName.lastIndexOf(".") + 1);
        }
        else return null;
    }
}