ECS comparison between Java and DragonRuby

main.java

// main.java
package my.game;
import com.artemis.*;
import my.game.components.Hello;
import my.game.systems.HelloWorldSystem;

public class GameLauncher {
    public static void main( String[] args ) {
        WorldConfiguration setup = new WorldConfigurationBuilder()
                .with(new HelloWorldSystem())
                .build();

        World world = new World(setup);

        int entityId = world.create();
        world.edit(entityId).create(Hello.class).message = "\n\rHello world!\n\r";

        world.process();
    }
}

//systems/HelloWorldSystem.java
package my.game.systems;
import com.artemis.ComponentMapper;
import com.artemis.annotations.All;
import com.artemis.systems.IteratingSystem;
import my.game.components.Hello;

@All(Hello.class)
public class HelloWorldSystem extends IteratingSystem {
    protected ComponentMapper<Hello> mHello;

    @Override
    protected void process(int id) {
        System.out.print(mHello.get(id).message);
    }
}

//components/Hello.java
package my.game.components;
import com.artemis.Component;

public class Hello extends Component {
    public String message;

    public void set(String message) {
        this.message = message;
    }
}

main.rb

def tick args
  args.state
      .entities
      .player ||= args.state
                      .new_entity(:player) do |entity|
    entity.message = "Hello world"
    entity.systems = [:hello_world_system]
  end

  args.state.entities.as_hash.each do |name, entity|
    tick_hello_world_system entity
  end
end

def tick_hello_world_system entity
  return unless entity.systems.include? :hello_world_system
  puts "#{entity.message}"
end