I'm still in university at the moment, and I'll likely either try to get security or programming job. My first programming course used a custom library that came with the book. It replaced and added many of the basics of Java like Arrays, completely custom math functions, input (scanner), Hashmaps, Queues and Stacks.
If I did land a programming gig, is it considered unprofessional to use a given custom library such as the one above? Either way, I've pretty much weaned myself off of 75% of the custom classes in favor of standard Java classes/objects, but I wanted to know if slipping in a premade class from a textbook is frowned upon. Thanks guys.