The next lesson is entitled "A Closer Look at the "Hello World!" Application", and it opens with the phrase "Here again is its code".
If I opened a lesson thus, I think I would quote the entire content of the source file. It is after all only 8 lines. But in the actual lesson, the non-comment section of the code is quoted, and guess what the lesson talks about first: comments. Perhaps it is a trivial point. Perhaps no one else has noticed. But for me, the non-java programmer, it caused me to stop, to read it twice, to work harder to understand what it all meant and where it all fitted in.
I guess the rest of the lesson flows OK, but if I were feeling picky, and I am, I'd make two comments.
The first is the Hello World is a really feeble tool to illustrate programming concepts. I grant that some of the important components are in there, but it's so dull, and it is not thorough.. A practical programmer want a method to do a little more than simply display an inane message. There is no explicitly declared object (to the non-java programmer this whole class thing is gibberish, until it is properly explained), and there are no defined variables or fields.
The second is that a practical illustration (like this, with the main components of code highlighted) might perhaps be better placed after or at the end of the theory trails.