Understand the JVM so you can love Clojure

The number of undefined terms in documentation can be infuriating. What is a CLASSPATH? What's PermGen? Do you get lost in the massive standard library? Have you ever given up on an exception because you were crushed under the weight of the stack traces? Do you hate using Java directly instead of a nice Clojure wrapper? The number of things to learn just to start using Clojure is enormous.

The truth is, the JVM is a big, complicated system that has evolved over time. Clojure sits on top of it like a rider on a horse. When a Java programmer gets into Clojure, it's all gravy. They already know the ins and outs of Java and the JVM, so to have a sweet language like Clojure to control it, they squeal with joy. But if you don't have that JVM experience, the squeals are not joyful. It is definitely confusing.

Wouldn't it be nice to skip 10 years of Java experience and see what the experts see?

Sure, you're not going to become an expert overnight. That's not what I'm talking about. However, some of the concepts are more important than others. In fact, the stuff that a Clojure programmer needs to use most days is quite small. If you learn just those, you'll be playing on easy mode. Further, you can learn the tricks experienced Java people use to find out what they don't know. It's often as easy as googling the error message.

Introducing JVM Fundamentals for Clojure

This course teaches you the hands-on, nitty gritty details of the JVM and Clojure/Java interop that you would pick up after many years of programming Java. It combines videos with reference sheets to give you easy access to the accumulated skills of years of experience. With this course, you won't have to worry about stack traces, JVM options, or the standard library again.

Topics covered:

• Calling methods and accessing fields.
• Class and method introspection.
• Reading Javadocs.
• Handling and raising errors and exceptions.
• Manipulating Java arrays.
• Dealing with dates and times.
• Understanding the classpath.
• The anatomy of a JAR
• Controlling JVM memory usage.
• Running java and Clojure programs from the command line.
• Doing I/O on the JVM
• Helpful macros for manipulating stateful objects

What people are saying

I just wanted to say thank you for making a lesson out of my suggestion. I watched it today and think it is really excellent. JVM Fundamentals is really a jewel of learning material. Congratulations and thanks for your great work.

Jorge Duenas

I can't overstate the importance of your courses on JVM, namespacing, and lein. I know they're much drier and not as "sexy" as the FP courses but as the tech lead and architect for our systems (we're a Python/JavaScript shop but I've been salivating over clojure/cljs for awhile) my lack of understanding of those topics has been the major hurdle for me adopting the language for major products, since if anything goes wrong it's my head on the chopping block. It's something I could learn on my own but time is super precious. These courses have given me the confidence to greenlight the adoption of Clojure. From a senior engineer perspective they're way more important than the "how to program" courses (although I enjoy those too).

James Tolton