Are any of the Google's App Engine sample apps written in Java?

I was looking at this repository of sample apps for Google App Engine:

http://code.google.com/p/google开发者_如何学JAVA-app-engine-samples/

The strange thing is they all seem to be in Python.

Are there any Java sample apps for GAE?

There are some well documented code samples here. They accompany a book but feel useful as a stand alone, too. You can find an overview in the README_java.txt .

Update

These are sources of another book.

This is nice example for beginners.

http://www.vogella.de/articles/GoogleAppEngineJava/article.html

All the examples in that repository are currently Python only. Here's an example app from I/O 2009 that's written in Java: Plane-crazy.