在“ Java构建路径” Eclipse中的“添加类文件夹”之后，无法在“参考库”中导入类

Question

I'm trying to include package X in project B as reference in my project A. Both project A and B are in my same workspace. Both A and B are Android/ Java projects.

I click on " Add Class Folder " in " Java Build Path " in Eclipse and choose package X folder and now it appears under " Referenced libraries " in my project A:

Reference Libaries
   src/[path-to-package-X]

Now I'm not able to import a class in that folder. Eclipse is not making any suggestion either.

import sg.xxx.xxx.xxx.ABaseClass;//sg.xxx.xxx.xxx is the package X  
==> The import "sg" cannot be resolved

Why doesn't it work? What am I doing wrong here?

*Notes:
Project B is huge so I only want to include package X but not anything else.

Answer 1

It's much better to add the project as a "referenced" project in {project} / right-click / Properties / Java Build Path / Projects / Add.

Another alternative is to keep producing .jar s and add them as libraries. Useful is this part of the code is stable enough.