protected boolean has(Entity entity,
			Class<? extends Component> componentClass) {
		int entityId = entity.getId();
		int componentId = getId(componentClass);
		Bag<Component> components = componentIdToComponents.get(componentId);
		if (components == null) {
			return false;
		}

		Component component = components.get(entityId);
		if (component == null) {
			return false;
		}

		return true;
	}