A Custom Build System for Sublime to Make it Easier to work with Java ... Scripts... "Scripts that use Java"?

I like using Java to write scripts. It's particularly easy with two features in Java: Java can run source code, and you can have class-less main methods.

The fact that you can launch a Java program with java Main.java (e.g.: I didn't point java, the runner, to .class files, but instead I pointed it to a source code file). If you want to use preview features, you also need to specify the source and specify that you want to use preview features.

So, given a program in Main.java, the full incantation would be:

java --source 21 --enable-preview Main.java

Preview features are worth remembering, because there's a doozy of a preview feature in at least Java 21 (or later) that allows you to run Java programs without the ceremonial public static void main. So, the following is valid:

void main() { 
	var name = "Josh" ;
	var message = STR."""
			 Hello, \{name}!
	""";
	System.out.println(message);
}

Nice!

A lot of times I just write quick and dirty Java programs to do file management chores or automate something on my local desktop. I develop these single-page applications in Sublime and I want to run them. It's not easy. Sublime knows how to compile a .java program, but it doesn't know how to run it. It's easy enough to teach it, however.

Go to Tool > Build System > New Build System. It'll popup with a partially completed source code buffer. Use the following instead:

{
  "shell_cmd": "java --source 21 --enable-preview $file",
  "selector": "*java"
}

Save the file (File > Save, or CMD/CTRL+S on your operating system of choice). It'll save it automatically in your system's correct build plugins folder. On my system that folder is: $HOME/Library/Application Support/Sublime Text/Packages/User/. Yours might be different. No idea. I installed my Sublime through Homebrew, for what it's worth...

Now, create a new file called Main.java (or Cat.java, it really doesn't matter!) and add the following code:

Then run the build. On macOS, it's CMD+B. Voilà! REPL-like productivity with a statically typed language you already know and love.

This approach is super liberating. Half of the interesting things I may want to do seems to revolve around java.util.* and java.io.*. I just remember to import those, and start writing. If I can write the whole thing from memory of the types involved, fine. If not, or if the the thing gets more involved, it's just Java. I can always promite it to its own Maven or Gradle project. No big deal.