A small applet to crack the static java.util.Random object present in Minecraft's Dropper and Dispenser classes given only output from an in game redstone device.
To use the applet, first build and launch the application (Or use the binary found under the releases tab) and then open the Minecraft 1.15.2 world file Dropper_Cracker.zip found under the releases tab. Press the birch button found in this world, wait approximately 30 seconds, and then check the boxes corresponding to the lamps which have lit up. The program outputs the current internal seed of the Dropper/Dispenser Random object. Since the Random object is static, this will be the internal seed for any dropper in any world until Minecraft is closed or a Dropper/Dispenser fires, meaning that one does not have to physically build the device in one's world to gain the same knowledge (with the exception of servers).