You cannot play a jar on android. It only plays apk files. If you open up the "Balloons" file in the project folder in eclipse, you can create an apk file out of it. However, you need to have downloaded eclipse and the android plugins at this link first: http://developer.android.com/design/downloads/index.html.

@Erdelf, its fine, this is meant to be a learning thing. @paulmartin42, honestly, downloading android and eclipse is complicated, and I think that google does the best job explaining it here: http://developer.android.com/sdk/index.html.

Yes, it works on others, but you'll have to change the 'target' of the APK file. You do this by changing the project description file.

What is the best way to do this with my own scenario's? Really, i downloaded it all, but it just doesn't get to load. Could one write a simple tutorial?

@groengeel, you do not have to change the target, android operating systems run all apps designed for that version or for any version older than these. For example, I designed this around 2.2, but it will run on my nexus 7, which runs jellybean (4.1/4.2). As for your other question, android coding is quite different from Greenfoot coding. It all runs java, but the methods are different. I am thinking about doing a tutorial to show some of the major differences like you suggested, but there may be a couple other options in the near future (they are mentioned in this discussion: http://www.greenfoot.org/topics/find/4412#post_4412).

Would you introduce my Greenfoot4Android? For it's very like Greenfoot. As you are my first user, you may share your experience with others.

Just write something about how to use it. From downloading Eclipse or dropbox to how to do the convert. You know, the first step out from Greenfoot could be tough to new learners.

After a few complications, I made eclipse to make an apk file and installed it on two Galaxy S2 devices with android version 2.3 and 4.0.4. and it works without problems. Great job.