How do you use a Java project in your Android project in Eclipse?

Question

I'm writing an Android application and there's some Java code in it that's somewhat sophisticated and therefore hard to verify the correctness of in the Android environment. I would like to run this code in a desktop environment where I have more tools with which to examine the output of this code while still using it in my Android application.

My attempted solution is to have three different projects in Eclipse. My Android project and two plain (non-Android) Java projects. One Java project has the sophisticated code that I want to use in Android and the other is a test program that verifies the correctness of the former project. The latter project has already been useful in debugging the former.

However, so far, my attempts to use the Java project in my Android project appears to work in the IDE but when I actually run the Android application, the NoClassDefFoundError exception is thrown whenever I try to access any of the classes. Obviously, that code is not being recompiled into the .dex file but why not?

I could go into detail about what I've done so far but I can't help but think that what I'm doing is a pretty standard and simple thing and there's a plain way of doing it, even though I can't find anyone doing quite what I'm trying. Can someone describe to me how this is done?

Answer 1

Luckily, I found the answer to my own question and I thought I'd share it here to help others in the same situation. It turned out to be very simple...

What I was already doing would have normally worked, which should have been a big clue to me since I have actually done this before, successfully. All you have to do is, under your Android project's Properties > Java Build Path > Projects , add the plain Java project to your " Required projects on the build path " and then under Properties > Java Build Path > Order and Export , check the checkbox of that same project in the " Build class path order and exported entries " list and everything should just work.

From within Eclipse, there's nothing else you need to do to get this setup to work. It's only when you're compiling from the command line that you need to build Java Jars and import them as libraries but I'm not doing that (yet).

Finally, this wasn't working for me because I just happened to be compiling my plain Java project under JDK 1.7 compliance, while my Android project was compiled under JDK 1.6. This is verified by the output on the Console pane, reporting " Dx bad class file magic (cafebabe) or version ." This error message goes away when both projects are compiled under the same compliance level and, not coincidentally, the Android program runs properly.

Thank you to everyone who tried to help and I hope this answer is helpful to someone out there!

Answer 2

如果你把你的其他普通java项目变成一个Android项目并使用它监视设备上的输出，它会不会工作？