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How to Code Minecraft Plugins!
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AstOwOlfo

How To Code a Minecraft Plugin


After many years of waiting, today I can officially announce that Minecraft Plugin Development has come to replit! With this tutorial you will understand all you need to know on how to create the basic boilerplate for a standard Java edition plugin for the Spigot API.

This guide is geared towards creating a plugin on repl.it but will also work for IDEs such as Intelij IDEA and Eclipse (I recommend Intelij out of the two)

For any assistance feel free to leave a reply or join my Discord server discord.gg/zfgVqZv

Background Information


Minecraft Java plugin development can be done for a variety of different APIs such as CraftBukkit, Spigot, PaperMC, Bungeecord, etc.

A Minecraft plugin is essentially a library built on these APIs that will allow you to interact with the API to create custom gamemodes, administration utilities, and much more!

Plugins are typically cross compatible with the main APIs but if you use methods specific to PaperMC it will not run as intended on CraftBukkit or Spigot servers, so be careful if cross-compatibility is a concern for you.

In this tutorial we will be building our plugin on the Spigot API using Maven as our build tool (Gradle is not available on repl.it as far as i’m aware).

Getting Started


Maven

Create a new Java repl and then go to the terminal/console.

Type the following commands in this order:

  • rm *
  • mvn archetype:generate

After that, you should begin to see Maven (a java build tool) spit messages in console. Leave it for a minute until it asks you to start inputting information for your project.

The first message you see should be along the lines of

Choose a number or apply filter (...):

For this, choose the latest version, for example if I was given this:

1: 1.0-alpha-1 2: 1.0-alpha-2 3: 1.0-alpha-3 4: 1.0-alpha-4 5: 1.0 6: 1.2 7: 1.3 8: 1.4

I would enter 8 into the console.

After this you will see a message asking you to input your groupID. For this, if you have a domain then enter tld.yourdomain, for example I own the domain astolfo.tech so I would enter tech.astolfo. If you don’t have a domain then use me.yourname.

After this it will ask you for your artifactID, this is basically the name of your project. So, just enter what you’d like to call your plugin without any spaces or special characters. Example: tutorialplugin

Once you’ve entered your artifactID it will ask for your plugin version, just put 1.0-SNAPSHOT to start with. It doesn’t really matter what goes here but in the end it will be the prefix of your compiled jarfile.

Once that’s done it will ask for what you’d like the package to be named. In this case enter your groupID+artifactID, for example: tech.astolfo.tutorialplugin or tld.yourdomain.plugin

When that’s over it will ask you to confirm, enter Y, and then you should see this:
Build Success


Pre-plugin Setup

You should see a folder in your files with the name of your artifactID, click it and open the pom.xml file.

Delete what’s currently in your pom.xml and paste the following:

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>REPLACE WITH YOUR GROUPID</groupId> <artifactId>REPLACE THIS WITH YOUR ARTIFACT ID</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <name>REPLACE THIS WITH YOUR PLUGIN NAME</name> <description>REPLACE THIS WITH A DESCRIPTION OF YOUR PLUGIN</description> <properties> <java.version>1.8</java.version> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <url>https://astolfo.tech</url> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.8.1</version> <configuration> <source>${java.version}</source> <target>${java.version}</target> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-shade-plugin</artifactId> <version>3.2.2</version> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> <configuration> <createDependencyReducedPom>false</createDependencyReducedPom> </configuration> </execution> </executions> </plugin> </plugins> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> </resource> </resources> </build> <repositories> <repository> <id>spigotmc-repo</id> <url>https://hub.spigotmc.org/nexus/content/repositories/snapshots/</url> </repository> <repository> <id>sonatype</id> <url>https://oss.sonatype.org/content/groups/public/</url> </repository> </repositories> <dependencies> <dependency> <groupId>org.spigotmc</groupId> <artifactId>spigot-api</artifactId> <version>1.8.8-R0.1-SNAPSHOT</version> <scope>provided</scope> </dependency> </dependencies> </project>

Make sure to replace the values i’ve marked with your own values or your plugin will fail to compile!

Once you’ve modified the pom.xml file, navigate to src/main and create a folder called resources and then go inside that folder and create a file called plugin.yml
We will setup this file later!

After that go to src/main/java/groupID/artifactID and delete App.java.

Create a new file called YourPluginName.java and inside of it paste the following:

package YOUR-GROUP-ID.YOUR-ARTIFACT-ID; import org.bukkit.Bukkit; import org.bukkit.plugin.java.JavaPlugin; public class YourPluginName extends JavaPlugin { @Override public void onEnable() { } @Override public void onDisable() { } }

Replace the value for package on line 1 and the name of the class to the appropriate values.

After this, go back to your plugin.yml file and paste the following:

name: NAME_OF_PLUGIN version: ${project.version} main: YOUR-GROUP-ID.YOUR-ARTIFACT-ID.YourPluginName prefix: CONSOLEPREFIX authors: [YOURNAME] description: REPLACE THIS WITH A DESCRIPTION THAT WILL BE SHOWN WHEN PLAYERS DO /about <YourPlugin> website: YOUR WEBSITE

Here’s an example of a working plugin.yml file:

name: TutorialPlugin version: ${project.version} main: tech.astolfo.tutorialplugin.TutorialPlugin prefix: AstolfoTutorial authors: [AstolfoDev] description: An example plugin for my replit tutorial! website: https://astolfo.tech

Setting Up Your Repl

Now that we’ve sorted all that out, create a .replit file in your project root and paste in the following:

language="Java" run="cd YOURARTIFACTID && mvn clean install"

Remember! Replace the marked value with your own

This will automatically compile your code whenever you click the run button!


Creating a Command

Now that we’ve sorted out all the basics, let’s begin creating our first command!

To start, go to your plugin.yml file and add this to the bottom of the file:

commands: COMMANDNAME: usage: /<command>

Replace COMMANDNAME with what you want the player to type in game, for example a command called tutorial will be run when you type /tutorial in game. For a full list of command properties read this documentation

After that navigate to src/main/java/groupID/artifactID and create a new folder called classes and inside that folder create a folder called commands.

Inside the commands folder create a new file called YourCommandName.java

Inside that file paste in the following boilerplate:

package YOUR-GROUP-ID.YOUR-ARTIFACT-ID.classes.commands; import org.bukkit.*; import org.bukkit.command.Command; import org.bukkit.command.CommandExecutor; import org.bukkit.command.CommandSender; import org.bukkit.entity.Player; public class YourCommandName implements CommandExecutor { @Override public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) { return true; } }

In this command I will show you how to send a basic message to the player. For more information on various that can be called on the player interface consult this documentation.

Inside our onCommand method (above the return true) we will define the Player as the command executor. To do this we will create a new Player variable called "p" by casting the "sender" variable like this.
Player p = (Player) sender;

Next, to send the message we need to use the Player#sendMessage() method like this: p.sendMessage("OwO");.

Our code should look like this now:

package tech.astolfo.tutorialplugin.classes.commands; import org.bukkit.*; import org.bukkit.command.Command; import org.bukkit.command.CommandExecutor; import org.bukkit.command.CommandSender; import org.bukkit.entity.Player; public class YourCommandName implements CommandExecutor { @Override public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) { Player p = (Player) sender; p.sendMessage("OwO"); return true; } }

If your code looks like mine then that means you’re on the right track!

Now, how do we let the plugin know we want this class to be responsible for the command we created in our plugin.yml?

Simple! Head over to your plugin’s main class (YourPluginName.java) and import the class for your command by writing

import YOUR-GROUP-ID.YOUR-ARTIFACT-ID.classes.commands.YourCommandName;

After that, add the following line inside the onEnable() method

getCommand("COMMANDNAME").setExecutor(new YourCommandName());

And that’s all there is to it! You can run the repl and use your compiled jarfile (located in src/target on your server to test it out!


Creating a Listener

Commands are great and all but what if you want to do an action when an event occurs? (Ex. When a player hits an entity) Well, that’s where listeners come into play!

Go to your classes folder and create a folder called "listeners" and inside it create a new file called YourListenerName.java.

Inside this file paste in the following boilerplate:

package YOUR-GROUP-ID.YOUR-ARTIFACT-ID.classes.listeners; import org.bukkit.*; import org.bukkit.entity.Player; import org.bukkit.event.EventHandler; import org.bukkit.event.Listener; import org.bukkit.event.player.*; public class YourListenerName implements Listener { } }

Remember! Replace the marked values with your own

Let’s create a new event handler which will prevent players from dropping items. To do this, create a new method with the player drop event as a parameter like this:

@EventHandler public void noDropItems(PlayerDropItemEvent e) { }

WARNING! Ensure you remember to put @EventHandler above the method or it will not work!

Inside our new method let’s get the player who dropped the item using the e#getPlayer() method and send him a message like this

Player p = e.getPlayer(); p.sendMessage("No littering!");

Now, let’s cancel the event so the player can’t drop the item using the e#setCancelled() method.

Our method should look like this now.

@EventHandler public void noDropItems(PlayerDropItemEvent e) { Player p = e.getPlayer(); p.sendMessage("No littering!"); e.setCancalled(true); }

If this is the case, we can move onto actually registering the listener.

Navigate to your main class again, import your listener class and inside your onEnable() method add a new line with the following:

getServer().getPluginManager().registerEvents(new YourListenerName(), this);

That’s all there is to creating a listener. More events can be found on the Spigot API documentation


Compiling your Plugin

Now that we’ve finished, press the run button and it should compile your plugin and put the .jar file for you to download in src/target.

If the build fails and throws an error, either check my working repl project repl.it/@agent9002/Tutorial-Plugin and see what you’ve done differently. Or, if you’re too confused then feel free to contact me.


Need Tech Support?

If you need any assistance feel free to leave a reply or join my Discord server discord.gg/zfgVqZv

Voters
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racax
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COBRAGAMING1
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zarooma
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BenPurifoy
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eldragonite
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yy90987723
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HugoSOUFFRE
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WeCodeDiscord
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ermidoodle
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Ravost
Comments
hotnewtop
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HahaYes

Nice!

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AstOwOlfo

Thank you for comment! Hope this was helpful. @HahaYes

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HahaYes

@agent9002 maybe amasad will like this. He really likes these posts

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AstOwOlfo

:o pog @HahaYes

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EpicGamer007

@HahaYes, Yeah, but I am to scared to @ him lol. I don't wanna get in trouble

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ironblockhd

look on his twitter, he has like 200 notifications i don't think you will get into trouble lol

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AstOwOlfo

@ironblockhd well I guess it would be rude not to invite the main man @amasad

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amasad

@agent9002 duuuude this is sick! @Scoder12 can we load the plugin into your minecraft server?

It would be huge if you can code and run the plugin all on repl.it

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AstOwOlfo

@amasad if you're talking about his recent post on repl share then that would definitely work as it uses PaperMC as it's jarfile (good choice @Scoder12 ;3). The problem though, is that it's running on a 1.16.1 version (the poor performance version), but with server config optimisations this could turn out real nicely.

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Scoder12

@agent9002 I'd be happy to include any changes you have in mind, I'm don't know anything about server optimization. I would appreciate if you could help integrate my server setup with your plugin tutorial!

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AstOwOlfo

Sounds great, i’ll contact you on Discord about this. @Scoder12

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HahaYes

@agent9002 lol why are you commenting on my section of the wall.

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CodeLongAndPros

@HahaYes Same cycles AGAIN. EDIT: I lost one.

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HahaYes

@CodeLongAndPros WHAT AGAIN

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HahaYes

@CodeLongAndPros T SERIES VS PEWDIEPIE ALL OVER AGAIN

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CodeLongAndPros

@HahaYes Oh no.

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anonymous360c

What the heck is going on and why are you talking about pewdipie @everyoneherewhohascommentedontheoriginalcomment

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lilykhan

cool post ;)

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AstOwOlfo

thanks @lilykhan :3

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zarooma

@AstOwOlfo were is the onEnable() method?

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zarooma

awsome

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QuanNguyen83

how to get the jar ?

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eldragonite

hi, why i cant see in the minecraft plugin tutorial the folder in src/target?

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QuanNguyen83

how to download jar in your project?

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AstOwOlfo

Download the file in src/target as you would do any other replit file @QuanNguyen83

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Chillicoder

What about Minecraft Bedrock edition???

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GunjanKumari1

aah! leave it i am going back to my repl minecraft search

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GunjanKumari1

not workig yet

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GunjanKumari1

the shell is all empty and console is boom you know

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AstOwOlfo
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skelesquidstd

Do I add PLUGINNAME-1.0-SNAPSHOT.jar, original-PLUGINNAME-1.0-SNAPSHOT.jar, or both to the plugin folder?

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AstOwOlfo

Don’t use the one with the “original-“ prefix. @skelesquidstd

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ALEJANDROGORRZE

nice tutorial
and i see from your username that you are a man of culture as well

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AstOwOlfo
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gentechnolgy

its not working for me

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AstOwOlfo

Could you give a bit more detail please? @gentechnolgy

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[deleted]

Great tutorial! But how do I get my plugin into Minecraft??

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AstOwOlfo

Drag and drop the compiled jarfile into the "plugins" folder @CarlosRosiles

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CoolBro4811

for the commands folder, do we create files actually called YourCommandName.java, or do we call it something else. Also, i tried to name it /help or something, and you cannot have a file with / in the name. ty btw for all of the help

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AstOwOlfo

You can name it Help.java or whatever you'd like as long as it's written with ASCII symbols, and no worries feel free to ask me whatever you'd like. @CoolBro4811

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CoolBro4811
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AstOwOlfo

No problem ;3 @CoolBro4811

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CoolBro4811

heyyyyyyyyyy how do you find the two ID folders. i got nothing. stuff keeps saying GO TO ARTIFACTID or smthn i dont have anything like that. :CCCCCCCCCCCCCCCCC

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AstOwOlfo

its the 2 values you configured when setting up maven @CoolBro4811

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CoolBro4811

@AstOwOlfo wtf is maven can i get a screenshot lol

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AstOwOlfo

@CoolBro4811
Screenshot 2020-10-09 at 23.33.34

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CoolBro4811

@AstOwOlfo ooh im stupid i named the groupID and artifactID
wow im so dumb xD ty for the help

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CoolBro4811

where is the project root folder? im not sure xD this like my 3rd time with java not including lessons

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CoolBro4811

@CoolBro4811 wait u can ping urself xDDDDDDDDDDDDDD

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CoolBro4811

@CoolBro4811 also just noticed @AstOwOlfo that in ur profile thingy when u hover over ur name it doesnt say u code java
HMMMMMMM

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CoolBro4811

@CoolBro4811 Nvm i figured it out from looking at urs

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AstOwOlfo

doesnt show java cause repl hates me @CoolBro4811

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anonymous360c

I have no idea how this works. Hover on my username. So to make it actually working minecraft, you would need some way to show the results right?

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AstOwOlfo
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anonymous360c

To make it actually have effects, you would need some way to show the results, right? And about "I have no idea how this works.Hover on my username", look at who I am and what I code with. @agent9002

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AstOwOlfo

You can use getLogger#info or a standard System.out.println(); to debug in console @anonymous360c

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ChezCoder

this is sick!

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AstOwOlfo

Cheers mate, I appreciate it. Hope it helps you out ;) @ChezCoder

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LeviSikes

Can you help me? When I enter the first two lines and run it, this is what it says:
javac -classpath .:/run_dir/junit-4.12.jar:target/dependency/

  • -d . Main.java
    Main.java:1: error: class, interface or enum expected
    rm *
    ^
    1 error
    compiler exit status 1

I do not know why. makes me think they know what I'm doing. I'm also new here.

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AstOwOlfo

dont run it in console, run it in "shell" @LeviSikes

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LeviSikes

@agent9002 could you tell me how to find it in "shell"?

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AstOwOlfo

@LeviSikes
Screenshot 2020-09-03 at 20.10.05

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LeviSikes

@agent9002 , I hope you have a lot of patience. I do not have that, I think.

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LeviSikes

@LeviSikes I mean the Shell tab

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LeviSikes

@LeviSikes I mean the shell tab

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AstOwOlfo

in that case, create a bash repl and do it inside there @LeviSikes

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LeviSikes

@agent9002 can you show me how?

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AstOwOlfo

oh wait what, no i misread your question. if you read my tutorial it explains this, you need to create a .replit file and put the details i wrote @LeviSikes

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Ricky_J_Aquino

How do I go about adding the libraries I want to the repl?

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AstOwOlfo

add them to your maven dependencies in the pom.xml file @Ricky_J_Aquino

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Ricky_J_Aquino

Having an issue where I am unable to run it. I went through the tutorial but I seem to be missing something.
https://repl.it/@Ricky_J_Aquino/plugin#factionfocus/

image

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AstOwOlfo

did you create the .replit file like I wrote in the tutorial? @Ricky_J_Aquino

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Ricky_J_Aquino

Yeah, it's there.
@agent9002

EDIT: I just realized I didn't have it in the root, that's my bad.

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AstOwOlfo

alright perfect, im glad thats sorted @Ricky_J_Aquino

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Ricky_J_Aquino

I am having an issue, it doesn't seem to like mvn.
image

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AstOwOlfo

create a new bash repl instead of a java repl and it should work @Ricky_J_Aquino

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Ricky_J_Aquino

Ok, will try that.
@agent9002

EDIT: It worked, thanks.

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AstOwOlfo

no problem, have fun @Ricky_J_Aquino

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Benramin

wait this includes spigot and BUKKIT? (intense confusion)

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AstOwOlfo

spigot is a fork of bukkit, so yeah. @Benramin

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Benramin

Me and my friend are making are own server and this really helped!
btw, this is java right? or am I just stupid.

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AstOwOlfo

glad to hear it! hope your server goes well.

yes, this is java ;D @Benramin

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[deleted]

itz no problem @agent9002

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JustAWalrus

Oh yeah minecraft, forgot about that game. Haven't played since 2012. I guess I outgrew it.

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AstOwOlfo

not a bad idea to get back into it, hypixel has peaked and the community is more alive than ever. @Wuru

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JustAWalrus

Don't have the time. I have my own custom operating system to program and manage. @agent9002

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Muffinlavania

(That one kid waiting for pocket edition)

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Leroy01010

me playing minecraft java: "yes! netherite!" i fall score:0
😡 😡 😡 😡 😡 😡 RAAAAAGGGGGGEEE!!!!!

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AstOwOlfo

very sad, no way to prevent this :( @Leroy01010

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Leroy01010