The classical Eclipse/Java way

Add a (workspace) library

• Right click the project you want to insert in.
• Click Properties.
• Select Java Build Path.
• Select the Libraries tab.

Now, it depends how you compile your library.
So either do an Add JARs... or an Add Class Folder.
Choose the external variant to use an external source.
That’s it.

Add a workspace project

• Right click the project you want to insert in.
• Click Properties.
• Select Java Build Path.
• Select the Projects tab.

Click Add... on the right side and you are done.

The additional Android way

Two steps are necessary:

• Mark the project you want to use as library project
• Reference the marked project

Mark the library project

Right click your project and select Properties.
Select Android on the left and tick the checkbox IsLibrary. Done.

Reference the marked project

Right click your project and select Properties.
Select Android on the left and Add... your marked project. It will be added to the list and is ready to use. Now you are able to access all classes and ressources (e.g. drawables, strings) from the referenced, marked project. Awesome, eh? 🙂