Minecraft Plugin Tutorial (in Kotlin) | Project Setup

The hardest part of getting into plug-in  development is sEtTiNg uP tHe dAnG pRoJeCt!   In this video, I’ll guide you through the process  as quickly as possible while still making sure to   actually explain what each step does. (coughs)  Just a heads up though. Java is janky and weird  

And you will end up banging your head against the  wall. This is normal power through it. (softly) I   believe in you. All right, the very first thing  you’re gonna wanna do is download IntelliJ IDEA.  

This is by far the best code editor for anything  to do with Java. So go ahead and download the   community edition, unless you feel like paying a  hundred or so dollars for the SAME program. And  

Once you’ve got that installed, come back here.  When you open it up, you’ll be greeted by a screen   something like this. Now you might think that  to create a project we’d want to go to “New   Project” and then select our programming  language. But no, no, no, no, no. First,  

You gotta go to “Plugins” and then we have  to search for a plugin in the marketplace.   This will make our life infinitely easier. Find  the plugin called “Minecraft Development”. Make   sure it’s the one with over 600,000 downloads,  then hit install. Mine’s already installed. All  

This does is add some project templates for all  sorts of Minecraft related stuff. But today we   are making a plugin, a Spigot plugin. That’s  why we’re gonna select “Paper” (chuckles). The   difference between Paper and Spigot is that paper  is about a million, bajillion times faster. And…  

Good. Whereas Spigot is the older version,  that is a separate project, and is worse. Okay,   make sure the project SDK is set to “17”. If you  don’t have 17 up here, you can click “Download   JDK” and hit version 17 and then choose one of  these. The reason for this is that Minecraft 1.18  

Uses Java 17. Now we can proceed by hitting the  next button. Okay, this is the worst screen in   the entire thing, because when you haven’t done  any Java development before you don’t know what a   GroupId is, and you don’t know what an ArtifactId  is. So what are they? Okay, confusingly, GroupId  

Is usually a website URL that you own, written  down, back to front… So for me, that would be   something like com.legitimoose. “But I don’t own a  domain!” I hear you saying. That’s fine. If you’re   doing it casually, what I would recommend doing is  putting in “me.yourname” or some unique thing in  

There. Why is this even here? Well, it’s here  to prevent overlaps of names. If two projects   have the exact same name, there could be a  potential conflict where Java doesn’t really know   what code you’re talkin’ about. This shouldn’t  be an issue. So go with “me.yourname”. So for me,  

That would be “me.legitimoose”. ArtifactId is like  the name of your project, but it’s all lowercase,   and with no spaces, and doesn’t start with a  number, and a couple other rules. By the way,   I put the full standard in the description in  case any of you are curious, like I am. I’ll  

Call this plugin extreme-flight, cuz we’re gonna  be making a /fly plugin. And for the version,   1.0 snapshot signifies that it’s a development  version of the 1.0 release. Down here we can   choose between Maven and Gradle, that’s the  project manager type thing. Maven is more popular,  

So I’m going with that. They do the same thing  though. All right, here’s our plug-in name,   it’s automatically filled this in, Plugin  Name: “Extreme Flight”, Main Class Name:   “me.legitimoose.extremeflight.ExtremeFlight”.  That’s fine. Minecraft version 1.18.1. Uh, that’s   not the latest, so we’ll have to change  that. Then we can set the description,  

The authors, the website, the log prefix for  server logs, plugins it has to load before,   dependencies and soft dependencies. None of which  we need. So let’s click “Next”. Then we choose   the actual project name, this is just for IntelliJ  IDEA. I’ll call this “ExtremeFlight”. By the way,  

Don’t put spaces here. I did that once and it  broke everything, and I don’t know why… Don’t   do it. All right, if you’re happy with all these  file locations, you can hit “Finish”. All right,  

Here we are with the w i d e s t borders you’ve  ever seen, and this is an empty Java plugin. Look   how easy that was. It has already set us up with  the whole thing. Let’s make a quick “Hello, World”   program. So a lot of people will tell you to do  “Bukkit.getConsoleSender().sendMessage(“Hello  

World!”)”. This is wrong, because every plugin  actually comes with a logger that will send   plugin signed messages to the server log so that  you know where your messages are coming from. To   access that from inside a Java plugin class, like  we’re in here, all you have to do is “getLogger()”  

And you might think it’s “.log”, no, it’s  “.info”. We’re sending information to the   server log. So here we can say “Hello world!”.  If you wanted to send a warning, you would do   “getLogger().warning” and then it would show up  in yellow. Cool, now we just have to put this into  

Our Paper MC server. How do we get this into a  nice file that we can load into our server? Well,   first you’re gonna want to hit the beautiful hot  key Control-Alt-Shift-S, or you could go to File >  

Project Structure, then go down to artifacts. For  some reason, Java uses the word artifact to mean   thing, like a file. We’re gonna hit this little  plus button to create one and then hit JAR and   then go to “From modules with dependencies”.  All of these default settings are totally fine.  

Don’t change them, hit “Ok”. All right, now this  output directory is where our jar will wind up.   Let’s change that to our server plugins folder. If  you don’t have a Paper server set up, there are a   million billion tutorials on YouTube. Just look  up “How to set up Paper server” and you’ll find  

Out how to get this. So you’ll see this plugins  folder go in there, copy the location of it,   and then paste that into the output directory. So  now when we build this thing, it will go directly  

Into our plugins folder and we won’t have to move  it around, hit “Apply”, or just hit “Ok”. Now we   should be able to build our plugin. So to do this,  we have to go to Build > Build Artifacts and then  

Go down here and then hit “Build”. That’s a lot  of button presses. So what I like to do is hit   Control-Alt-S, no Shift this time to get into our  regular settings, then go to Keymap and search for   “build artifacts”. And I like to just bind this  to f5 . That’s my preference. Alternatively,  

You can click “Include in project build” from  the JAR screen here. Make sure you hit “Apply”.   And then, when you click this little Build  Project button, it should build the artifact. Yes,   indeed it does. So that; is a much better  way of doing it. Now you can see our Extreme  

Flight plugin is in here and we can run our server  and see our beautiful message appear. Yeah, yeah.   It’s telling me everything’s out of date. That’s  fine. “Could not load uses the space-character   in its name”. Uh-oh, how do we change the plugin  name now? Isn’t it a little late for that? Well,  

Fear not because all that information is stored in  a convenient file called plugin.YML. In this left   side project browser here, you can open and close  this by hitting this Project tab here, go into our   plugin ExtremeFlight, go into the “Source” (src)  folder for all of our source code, go into “main”.  

Underneath Java is where all our Java code goes,  and under resources, plugin.YML! In here- oh,   you’ll see there’s our name. It’s even warning  us. It’s saying it needs to have no spaces in   it. Let’s remove that space and then build our  project again. Let’s see if it works this time.  

There it is. ExtremeFlight says “Hello world!”.  So now that we’ve got Hello world working in Java,   let’s just say I’m not the biggest fan of Java. I  much prefer a new up-and-comer called Kotlin. Now   the cool thing about Kotlin is that anything  you can do in Java, you can do in Kotlin.  

That means using the same libraries, using the  same Java virtual machine, it will be exactly the   same as compiled Java once you build it into your  plugin. And because IntelliJ IDEA is made by the  

Same company who creates Kotlin, they have made it  very, VERY easy to set up. All we’re gonna do is   right click on our entire project up here and hit  “Convert Java File to Kotlin File”. When I do that  

The first time, it’s gonna say, “Hey, Kotlin  is not configured in your project” so hit “OK”.   And now we’re gonna configure Kotlin, pick the  latest release. So right now, 1.7.0 is a release   candidate, so it’s not fully released. I’m gonna  go back to the last stable version of 1.6.21,  

Pick the latest one without anything at the end of  it and hit “OK”. Now it takes us into this scary   looking file (laughs). This is our pom.XML,  and this stores everything about the project   that we’ve got here. This is what Maven uses.  That’s our project manager type thing. And this  

Contains all the info of any dependencies, this  contains the GroupId, the ArtifactId the version,   what kind of packaging we’re gonna use, the Java  version. Oh, and now the Kotlin version. And if we   go all the way down here, you’re gonna see it also  includes the Paper MC API. Now remember earlier,  

When I said that we were actually using an  outdated version of the Paper API, you can see   we’re using 1.18.1, when we should be using 1.18.2  or whatever the latest version is at the time of   you watching this video. You’re never gonna  guess how we do this. That’s right. We change  

The text that says 1.18.1 to 1.18.2. Yes. That  is literally what you do. Now to get all this,   to take effect, we’re gonna have to reload Maven.  If we were to try and convert to Kotlin again,  

It would just say it wasn’t set up again  and you would end up adding more and more   lines of Kotlin to this thing. So to get it, to  actually update everything, we have to hit this   “Reload All Maven Projects” button. Always hit  the Reload Maven projects button.If you forget,  

You will be confused for days. It took me a very  long time to find out that I have to press this   button every time I add a dependency or change  anything in pom.XML. (sternly) Do not forget  

To reload your Maven project. And with the little  press we wait, and you’re gonna see it says   “Resolving dependencies” and “Downloading Maven  sources and documentation” down here. That means   it is going to all of these repositories and it  is looking for anything called Paper API under the  

GroupId io.papermc.paper. And then it is looking  for the 1.18.2-RO.1 Snapshot version. Now there   is a version with this name. You can see cuz it  hasn’t turned red, but actually there’s a full   release, so we no longer need to have snapshot on  the end there. I think I could be wrong. How do  

We find out what the latest version is? Well, it’s  on their website. That’s right here on papermc.io,   link the description, you can scroll down and  click this little tiny, Use Our API button,   and then it’ll tell you the stuff that you  have to add to your Maven thing. See? Yep.  

Here’s the latest version. Now, let me show you  something that confuses me just a little. Here   it says our Java version is 1.8 When it should  be Java 17 for a Minecraft plugin. Down here,   it also says 1.8 I’m gonna just change that to 17.  And in theory, everything should still work, but  

Strangely it was working before, so I don’t know  what that’s actually changing. (laughs) [I don’t   know if] it’s just changing some display  setting or if it’s making it run faster   or what, but if I do that, rElOad my Maven project  and then build my Extreme Flight plugin, then it  

Should still work. Imma just stop my server,  start it again. And we’ll see what we get. Yep.   Everything still works. Awesome. Now let’s finish  converting to Kotlin because now we have added all   the Kotlin dependency stuff here. We’ve specified  a version of our pom.XML, which means now  

If we right click on Extreme Flight, hit convert  Java File to Kotlin File, it will just do it,   or- it should… seems to have done nothing,  let’s try that again. I’m gonna try clicking   on the source cuz maybe it doesn’t think this is a  file or something, convert. Okay. That worked for  

Me. I swear. I’ve clicked on that before and it’s  worked fine. But that’s what I had to do today.   Don’t you just love development. “Some code in  the rest of your project may require”- yeesss,   do correct the code. Oh and instantly, literally  so fast, it has converted our thing into Kotlin,  

Notice how much more compact it is. Can we get a  before and after here? Yeah, that’s pretty good.   And that’s all it takes to get Hello world working  in Kotlin. I trust you can figure out everything  

Else from here. Seriously though. If there’s more  you want to know, let me know in the comments of   this video, what plugin tutorials you’d like to  see. I’ll put a link to some more of ’em here.  

If I end up making more, otherwise go watch my  devlogs where I make my own plugins. See ya!