By Alvin Alexander. Last updated: June 6, 2016
While writing some Java code today, I needed a method to get the extension from a filename. This code solved the problem:
public static String getFilenameExtension(String filename) { String extension = "NoExtension"; int i = filename.lastIndexOf('.'); if (i > 0) { extension = filename.substring(i + 1); } return extension; }
Given an input filename like foo.jpg, the getFilenameExtension
method returns the “jpg” part as a String
.
Warning: I have no idea what this method will do if you pass a null
value to it. Don’t do that. (I write my code without null
values these days, so I don’t think or account for situations like that.)