Your first class

Let's create a class that prints a message when its node enters the scene tree.

KotlinJavaScala

Create src/main/kotlin/com/yourcompany/game/Player.kt:

package com.yourcompany.game

import godot.annotation.Script
import godot.api.Node
import godot.global.GD

@Script
class Player : Node() {
    override fun _ready() {
        GD.print("Hello from Kotlin")
    }
}

Create src/main/java/com/yourcompany/game/Player.java:

package com.yourcompany.game;

import godot.annotation.Script;
import godot.api.Node;
import godot.global.GD;

@Script
public class Player extends Node {
    @Override
    public void _ready() {
        GD.print("Hello from Java");
    }
}

Create src/main/scala/com/yourcompany/game/Player.scala:

package com.yourcompany.game

import godot.annotation.Script
import godot.api.Node
import godot.global.GD

@Script
class Player extends Node {
  override def _ready(): Unit = {
    GD.print("Hello from Scala")
  }
}

This small example already shows the main building blocks:

• @Script makes the class available to Godot.
• Inheriting Node makes it a Godot script class.
• Overriding _ready() runs code when the node enters the scene tree.
• GD.print(...) writes to the Godot output.

Now trigger a build:

./gradlew build

After the build, attach the source file (Player.kt, Player.java, or Player.scala) to a node as you would attach a GDScript. Its filename, without the extension, must match the simple name of the script class: Player.kt declares Player.

If you rebuild while the editor is open, your classes are reloaded automatically.

Info

JVM languages are compiled. Godot cannot use a newly created or changed class until its build succeeds.

The signals and callables guide is a good next step once this class works. For complete control over which declarations Godot sees, read the registration guide.

Final project structure

Depending on the language, the source file belongs in one of these roots:

KotlinJavaScala

src/
  main/
    kotlin/
      com/
        yourcompany/
          game/
            Player.kt

src/
  main/
    java/
      com/
        yourcompany/
          game/
            Player.java

src/
  main/
    scala/
      com/
        yourcompany/
          game/
            Player.scala