Java and the Java Virtual Machine (JVM)

Any programmer with a few gray hairs remembers when Java was announced in 1996 by Sun Microsystems, and the excitement it caused. More than one programmer thought, Oh boy. Now I don't have to learn C++ which was actually no joke. It seemed to implement all the good parts of a class based object oriented language without the cruft and complexity of C++.

So what was the target environment for Java? The web browser. Java didn't even have a stand-alone run-time environment at first, but ran "applets" within a browser, or rather a browser that was Java enabled. When an intern at Bell Labs was able to give a demo after spending days working on it, it was a big enough deal for a department wide meeting to show it off.

In hindsight, the original role for Java has been taken over by its dumb little brother JavaScript (quoting JavaScript's author Brendan Eich.) Java can still run applets and some show up now and then, like WebX.

Java is a compiled language, but rather than compile to machine code, it generates byte code that runs on the Java Virtual Machine (JVM) for portability to different architectures. This also has a very useful side effect: Other languages can compile to byte code that the JVM runs, and they can take advantage of the huge number of Java packages and libraries that exist. Three that I'm familiar with are Groovy, Scala and Kotlin.

Groovy has been described as "Java for the 21st Century" because it gets around many of the restrictions and annoyances of Java. For years we've written Java code for existing projects, but used Groovy for scripts and utilities. Groovy accepts all Java syntax, but doesn't require classes and handles all exceptions as Java Runtime exceptions. Groovy added closures and lambda functions many years before Java. In fact, many of the new features in JavaScript ES6 like arrow functions were in Groovy as early as 2006, along with pure functional features that have only recently been added to Java.

Scala combines pure functional programming with imperative code. The new version 3 of Scala is a major rewrite that is really nice. There is a version that compiles to native executables rather than Java byte code, so it's not limited to the JVM.

Kotlin was originally written for Android smart phone development by Jet Brains, but is now popular for both the JVM and native environments. Like Scala and Groovy, it has a syntax that's easy to learn and program and full of modern features.

Choosing between Java and the other languages that run on the JVM is a tough choice these days. They're all good, and Java has come a long way since it came to being in 1996.

Java migrated from the browser to the Enterprise first with servlets and then Enterprise Java Beans (EJB). Today, EJB has been largely replaced by leaner platforms such as Spring Boot. Grails was developed to give Java a web-based environment similar to Ruby on Rails.

While working in a Java environment, I found Groovy to be a great help, especially for utilities. For example, a connection to a Teradata DB stopped working at Boeing.

To help see what was going on, I wrote a Groovy program to try to connect using our user name and password, and was able to. On a conference call, the question came up about our connection credentials, and I was able to confirm that they were working. The problem was somewhere else. My manager later commented that this saved everyone trouble in finding the solution.

One of the engineers had made an Excel spreadsheet showing usage stats for several services and databases, for his own use. Then he made the mistake of showing it to a manager, who immediately asked for weekly reports with the spreadsheet. I was on the conference call when this request was make, and I could tell that the poor engineer was not happy. He was very good, and very busy. I volunteered to take the job for him, much to his relief. I found an Apache Java package for writing to Microsoft Excel, and used it to populate the spreadsheet. Then I wrote a Groovy program to make the SQL queries and format the spreadsheet with proper dates and times, and email it to the interested parties. This went into a CRON job, and we all got back to our regular jobs with the process totally automated.

This was in 2010, before Go. My hope is that these stories show how I approach problems, and solve them in the best way we can. In a Java environment, I would probably do the same thing again. Otherwise, I'd use Go. But the bottom line is to get the problems solved in the best way possible. I can do the same thing for you.