class Meal {    Meal() {        System.out.println("Meal()");    }}class Bread {    Bread() {        System.out.println("Bread()");    }}class Cheese {    Cheese() {        System.out.println("Cheese()");    }}class Lettuce {    Lettuce() {        System.out.println("Lettuce()");    }}class Onion {    Onion() {        System.out.println("Union()");    }}class Lunch extends Meal {    Lunch() {        System.out.println("Lunch()");    }}class PortableLunch extends Lunch {    Onion u = new Onion();    PortableLunch() {        System.out.println("PortableLunch()");    }}public class Sandwich extends PortableLunch {    private Bread b = new Bread();    private Cheese c = new Cheese();    private Lettuce l = new Lettuce();    public Sandwich() {        System.out.println("Sandwich()");    }    public static void main(String[] args) {        new Sandwich();    }}/* 输出Meal()Lunch()Union()PortableLunch()Bread()Cheese()Lettuce()Sandwich()*///:~