A class folder is an ordinary folder containing a collection of class files inside the workbench. Use this format for a library when a library is not packaged as a JAR file. A the class folder is the root of the package folders so that all class files are by placed according to their package declaration.
To add a class folder to the project's build class path, follow these steps:
Adding a JAR file to the build path
Building a Java program
Building automatically
Building manually
Viewing and editing a project's build path
Working with build paths