Main.java

package io.colyseus.example.java;

import io.colyseus.Client;
import io.colyseus.Room;
import kotlin.Unit;
import kotlin.coroutines.Continuation;
import kotlin.coroutines.CoroutineContext;
import org.jetbrains.annotations.NotNull;

public class Main {
    public static void main(String... args) {
        Client client = new Client("ws://localhost:2567");
        client.joinOrCreate(MyState.class,
                "game",
                null,
                null,
                null,
                new Continuation<Room<MyState>>() {
                    @NotNull
                    @Override
                    public CoroutineContext getContext() {
                        return null;
                    }

                    @Override
                    public void resumeWith(@NotNull Object o) {
                        Room<MyState> room = (Room<MyState>) o;
                        System.out.println("connected to " + room.getName());

                        room.getState().players.setOnAdd((player, integer) -> {
                            System.out.println("added player with x = " + player.x + " to index = " + integer);

                            room.send("fire", "in the hole!");
                            return Unit.INSTANCE;
                        });

                        room.getOnMessageHandlers().put("hello", new Room.MessageHandler<>(Object.class, s -> {
                            System.out.println(s);
                            return Unit.INSTANCE;
                        }));
                    }
                });
    }
}

MyState.java

package io.colyseus.example.java;

import io.colyseus.annotations.SchemaField;
import io.colyseus.serializer.schema.Schema;
import io.colyseus.serializer.schema.types.ArraySchema;
import io.colyseus.serializer.schema.types.MapSchema;

public class MyState extends Schema {
    @SchemaField(v1 = "0/ref", v2 = PrimitivesTest.class)
    public PrimitivesTest primitives = new PrimitivesTest();

    @SchemaField(v1 = "1/array/ref", v2 = Player.class)
    public ArraySchema<Player> players = new ArraySchema<>(Player.class);

    @SchemaField(v1 = "2/map/ref", v2 = Cell.class)
    public MapSchema<Cell> cells = new MapSchema<>(Cell.class);
}

class Cell extends Schema {
    @SchemaField(v1 = "0/float32")
    public float x;

    @SchemaField(v1 = "1/float32")
    public float y;
}

class PrimitivesTest extends Schema {
    @SchemaField(v1 = "0/uint8")
    public short _uint8;

    @SchemaField(v1 = "1/uint16")
    public int _uint16;

    @SchemaField(v1 = "2/uint32")
    public long _uint32;

    @SchemaField(v1 = "3/uint64")
    public long _uint64;

    @SchemaField(v1 = "4/int8")
    public byte _int8;

    @SchemaField(v1 = "5/int16")
    public short _int16;

    @SchemaField(v1 = "6/int32")
    public int _int32;

    @SchemaField(v1 = "7/int64")
    public long _int64;

    @SchemaField(v1 = "8/float32")
    public float _float32_n;

    @SchemaField(v1 = "9/float32")
    public float _float32_p;

    @SchemaField(v1 = "10/float64")
    public double _float64_n;

    @SchemaField(v1 = "11/float64")
    public double _float64_p;

    @SchemaField(v1 = "12/boolean")
    public boolean _boolean;

    @SchemaField(v1 = "13/string")
    public String _string;
}

class Player extends Schema {
    @SchemaField(v1 = "0/int32")
    public int x;
}