I could be wrong here but I have not found my jar file either. I thought it might be in "tempjar" but no luck. I copy the file from my PC to the Pi with an USB stick. On the PC it is called "result.jar" and you find it in the objects directory in your project.
Edit: In the examples from Erel, "BouncySmiley", the file is called BouncySmiley.jar but I cannot see where to set the name. It could be just the name of the project.