The following function removes extension from a filename using Java. However it will not modify the hidden file names in mac/linux which starts with a dot character.

A different implementation is available as part of the Apache commons IO library.

// Java example: removes extension from a file name.
public class ExtensionRemover {

    public static void main(String[] args) {
        String fileName = "a.hello.jpg";
        System.out.println(removeExtension(fileName));

    }

    // Remove extension from file name
    // Ignore file names starting with .
    public static String removeExtension(String fileName) {
        if (fileName.indexOf(".") > 0) {
            return fileName.substring(0, fileName.lastIndexOf("."));
        } else {
            return fileName;
        }

    }
}