The Clippings class allows you to parse the 'My Clippings.txt' file containing your kindle highlights. The input is the aforementioned file, while the output is a file per book, containing the numbered highlights. If your My Clippings.txt file contains highlights from more than one book, then the output is more than one file.
Run the Clippings.java main method with a program arg pointing to the location where the clippings file is stored. The program args can be configured in the Intellij launcher, in the "Program arguments" field.
Example:
"/home/user/My Clippings.txt"
If the class is exported as a jar then pass the arguments to the main function similar to:
java [ options ] -jar clippings.jar "/home/user/My Clippings.txt"