I have a project “A” and I need to call a class “c” from another project “B”.
I have done the following. Click in “A” –>Properties –>Build Path –> and in one tab of Java Source I selected the project B. –> Accept
Now I can create objets of Class “c” but when I run the project I get “ClassNotFoundException”
Update,
I keep getting java.lang.ClassNotFoundException.
In “JSF” –>Properties –>Build Path –> Projects —> I Added the Project:

In Run –> Run Configurations –> ClassPath I had:

and now I have added the project “JIRA” and “JIRA dependencies”

JIRA project has this dependencies:

And I get the following error:

but this class is in M2_REPO:

SOLUTION
I add “JIRA dependencies” only in JARs without Maven:

and now it´s run.
You need to add project B to the Run configuration used by project A. In the menu Run -> Run configurations… , add the project B in the tab ‘classpath’ of your run configuration.