I have created a reaction time measurement java applet 10 years ago with JDK1.0.2.

This is the EJS version of the same applet. You can see how it was created with ejs (and all the model) if you click the link below the applet(Loas it as signed applet).

VIEW or DOWNLOAD ejs xml source
then click to translate strings for selected locale.

Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop.

Click after the simulation is paused.