public class TrainCar {
    private String _id, _cargo, _src, _dest;
    public TrainCar(String id, String cargo, String src, String dest) {
	_id = id;
	_cargo = cargo;
	_src = src;
	_dest = dest;
    }
    public String as_string() {
	return "car " + _id + " carries " + _cargo + " from "
	    + _src + " to " + _dest;
    }
}