I have been asked numerous times to show the App Inventor Java Code. So here is a zipped archive for all the class files. You can take those classes and easily open them with a program called JD GUI. There are versions of it for every OS.
I got the code pretty easily with 2 programs being the apktool and Dex2Jar. They can convert APK files into the class files most of the time. After you install them you issue the following commands in your terminal or command prompt:
That generates all the class files for your apk file. I hope that helps 🙂
If you know anyone that is interested in doing this feel free to share on Google Plus here