Java Question Debugging libraries

Is there an easy way to debug libraries? While using b4a as a testbed?
Can I write out log messages, or even display a messagebox through java without adding any additional libraries?
Thanks!

The easiest way is to write log messages. You should use the B4A tag:
You can also compile your B4A project (from B4A IDE), take the generated source code and make it an Eclipse project. This will allow you to debug your program and library from Eclipse.

Thats quite useful to know!!
Thanks.