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 Lunch extends Meal {
  Lunch() { System.out.println("Lunch()");}
}

class PortableLunch extends Lunch {
  PortableLunch() {
    System.out.println("PortableLunch()");
  }
}

public class Sandwich extends PortableLunch {
  Bread b = new Bread();
  Cheese c = new Cheese();
  Lettuce l = new Lettuce();
  Sandwich() {
    System.out.println("Sandwich()");
  }
  public static void main(String[] args) {
    new Sandwich();
  }
}

很简单啊!运行一遍不就知道了。

为什么没有main（）方法？从哪里开始运行？

Sandwich()

Meal()
Lunch()
PortableLunch()
Bread()
Cheese()
Lettuce()
Sandwich()

楼上正解

编译运行呗。

对象在初始化的时候，先调用父类的构造方法，然后初始化属性，最后调用自己的构造方法！！！！

Bread()
Cheese()
Lettuce()
Sandwich()