In Eclipse, the classes that you develop in the Visual Editor for Java must be stored in Java projects. Each Java project has a build path that includes references to other projects inside Eclipse or external JARs that exist in the file system. The packages included in the build path are used to compile the project's classes, and are also used by the Visual Editor for Java to create the class path of the virtual machine where runs the Java beans at design time.
In Eclipse, there are several ways that you might organize your resources:
Related concepts
BeanInfo classes and introspection
Related tasks
Keeping beans and BeanInfo classes in the same package
Keeping beans and BeanInfo classes in different packages in the same project
Keeping beans and BeanInfo classes in different projects
Keeping BeanInfo classes in a JAR file
Explicitly defining the location of BeanInfo classes
Related reference
BeanInfo classes for JRE classes
BeanInfo classes for the Visual Editor for Java