How can I use external JARs in an Android project?

I have created an Android project and added an external JAR (hessian-4.0.1.jar) to my project. I then add the JAR to the buildpath and check it off in Order and Export.

Order and Export is ignored it seems, and all classes from the external JAR are missing in runtime.

Is there a trick to properly include the needed classes from an external JAR when building an Android application using the Eclipse Plug-In. I do not want to use ant or Maven.

I know the OP ends his question with reference to the Eclipse plugin, but I arrived here with a search that didn't specify Eclipse. So here goes for Android Studio:

1. Add jar file to libs directory (such as copy/paste)
2. Right-Click on jar file and select "Add as Library..."
3. click "Ok" on next dialog or renamed if you choose to.

That's it!

Posted in: Android