将Java文件导出为android中的外部jar

Question

how can i export one of my classes (non activity) and use it as external jar in my application. I need to do this because of reasons.

I have tried to remove my package name from top of my class. Then via eclipse export as jar file and added to my projects. I got no errors in the code but when I ran the application it crashed with:

E/AndroidRuntime(12762): FATAL EXCEPTION: main
E/AndroidRuntime(12762): java.lang.Error: Unresolved compilation problem: 
E/AndroidRuntime(12762): The declared package "" does not match the expected package "com.myapp"

The thing is I wish that this jar can be used in any other application and package

Answer 1

Some solutions:
1) You can write a little project with this class, and make it library (project Properties -> Andoid -> enable Is Library -> OK). Then you can include this lib-project in another project (project Properties -> Andoid -> Add -> pick this lib-projectt -> OK.)
2) You can create class with same name, and then copy past all code into.
3) You can create jar file with this class, and then include it as library. Use this tutorial to create jar file.

Answer 2

Eclipse automatically generates .jar files of your library projects in the /bin folder. You can copy this file and use it in other projects.