Remove filename extension in Java

Question

(Without including any external libraries.)

What's the most efficient way to remove the extension of a filename in Java, without assuming anything of the filename?

Some examples and expected results:

• folder > folder
• hello.txt > hello
• read.me > read
• hello.bkp.txt > hello.bkp
• weird..name > weird.
• .hidden > .hidden

(or should the last one be just hidden?)

Edit: The original question assumed that the input is a filename (not a file path). Since some answers are talking about file paths, such functions should also work in cases like:

• rare.folder/hello > rare.folder/hello

This particular case is handled very well by Sylvain M's answer.

Answer 1

Using common io from apache http://commons.apache.org/io/

public static String removeExtension(String filename)

FYI, the source code is here:

http://commons.apache.org/proper/commons-io/javadocs/api-release/src-html/org/apache/commons/io/FilenameUtils.html#line.1025

Arg, I've just tried something...

System.out.println(FilenameUtils.getExtension(".polop")); // polop System.out.println(FilenameUtils.removeExtension(".polop")); // empty string 

So, this solution seems to be not very good... Even with common io, you'll have to play with removeExtension() getExtension() indexOfExtension()...