java - Java Class Loaders Hierarchy

Question

There is very good article on class loading. But this opens many questions in my mind.

I understand the hierarchy of class loaders (Bootstaper, Extension, System), but my question is are they real classes extending in the manner? If yes

1. Can I see the Java Doc of these classes?
2. What is the relationship of these classes with class "java.lang.ClassLoader"

If no, what are they (instances?) and how is the hierarchy defined?

In case I am missing a whole big concept, you may want to cite me to some good article.

Answer 1

Custom class loaders are just instances of Java objects, as you already stated.

Can I see the Java Doc of these classes?

Yes, if you have the sources or JavaDocs, as with any other class.

What is the relationship of these classes with class "java.lang.ClassLoader"

ClassLoader is the abstract base class that all concrete class loaders extend. An example of such a class loader would be java.net.URLClassLoader and java.security.SecureClassLoader.