“Sybex” - 1Z0-815 - Chapter 1 page 24

[Dean Kirby]

The section headed "Running a Program in One Line with Packages" states "You can use single-file source-code programs from within packages as long as they rely only on classes supplied by the JDK". This is incorrect. You can use user defined classes too.

[Mikalai Zaikin]

Hi Dean,

While we appreciate the errata you reporting, this is general Java certification forum, and not all people have the book. To add more value to your post, could you share for example your scenario -- source .java code and small demo how you run it from command line.

I am pretty sure many readers would appreciate these details. My guess is that the "user defined classes" must reside in the same source (either peer level or inner classes), no classes from user defined modules. Can we discuss in that direction?

Cheers,
MZ

[Dean Kirby]

Please see the following example

[Mikalai Zaikin]

I see, yes, so you have the Boo.class precompiled

Would be even better if you use Code button on the buttons panel, so other people can try your code. Screenshot is good, but own practice is the key for exam success 8)

MZ

[Dean Kirby]

Writing code helps in the learning process. Copy and pasting someone else' code doesn't really tick that box.

[Campbell Ritchie]

Writing code is part of your learning, yes. But seeing the exact code in text format allows us to verify the errors you might have found.

[Mikalai Zaikin]

Looking at JEP 330 (which should be the primary source of the information for this feature) I see it can use class path option and module path option in command line, so I am really puzzled what authors mean about depending on JDK classes only.

The source file is compiled in context of unnamed module (which can access unnamed module classes and/or named modules classes) and ran as well in context of unnamed module (which allows to access classpath and/or module path classes).

MZ

[Jeanne Boyarsky]

This is really interesting. I did not know you could do that. I checked both the spec and JEP 330. You are correct.

Good find!

(Incidentally since file source code execution is not on the exam. We covered it to make running the examples easier when studying for the exam)