Java API

The java global table allows interacting directly with Java classes and objects from your scripts.

NOTE

When interacting with Minecraft internals, all classes, methods, and fields use Mojang mappings. This means you must use the official, unobfuscated names as they appear in the Minecraft source code.

Core Functions

java.import(class_name)

Loads a Java class by its full package name. Returns a Lua representation of the class.

local Math = java.import("java.lang.Math")
print(Math:abs(-1))

java.new(class_obj, ...)

Creates a new instance of a Java class using its class object.

local ArrayList = java.import("java.util.ArrayList")
local list = java.new(ArrayList)
list:add("Hello")

java.newInstance(class_name, ...)

Creates a new instance of a Java class using its full class name.

local list = java.newInstance("java.util.ArrayList")
list:add("World")

java.proxy(interface_name, table)

Creates a Java proxy for an interface, using a Lua table for method implementations.

local my_runnable = java.proxy("java.lang.Runnable", {
    run = function()
        print("Running in Java thread!")
    end
})

Utility Functions

is_instance(obj, class_or_name)

Checks if a Java object is an instance of a specific class or class name.

local Player = java.import("net.minecraft.world.entity.player.Player")

if is_instance(entity, Player) then
    print("This is a player!")
end

if is_instance(entity, "java.lang.String") then
    print("This is a string!")
end