java - 如何创建另一个类的实例，加载带有数据的对象并将其打印出来？

Question

我是一个十足的菜鸟(第五天编程)，这解释了为什么我花了无数令人头疼的时间试图解决这个问题，但仍然没有弄清楚:

如何创建 CarAndBikes 实例，加载 3 辆汽车的信息并将其打印出来？

这是我不完整的代码，可以让您了解问题:

    public class Vehicle {

        String manufacturer, model;
        int numberOfWheels;

        public Vehicle(String manufacturer, String model, int numberOfWheels) {

            this.manufacturer = manufacturer;
            this.model = model;
            this.numberOfWheels = numberOfWheels;
        }

        public String getManufacturer() {
            return manufacturer;
        }

        public String getModel() {
            return model;
        }

        public int getNumberOfWheels() {
            return numberOfWheels;
        }

        public String toString() {
            return "(" + numberOfWheels +") '" + manufacturer + ", " + model + "'";
        }
    }

    public class CarAndBikes {

        private Vehicle[] items;
        private int nextFreeItem = 0;

        CarAndBikes (int size) {
            items = new Vehicle[size];

            for(int i = 0; i < size; i++)
            items[i] = new Vehicle(manufacturer, model, numberOfWheels);
        }

        void addVehicle(String man, String mdl, int wheels) {
            items[nextFreeItem++].addVehicle(man, mdl, wheels);
        }

        public String toString() {
            return "(" + items + ")";
        }
    }

public class TestProgram extends CarAndBikes{
    TestProgram(int size) {
        super(size);
    }

    public static void main(String[] args) {
        Vehicle vehicle1 = new Vehicle("Seat", "Ibiza", 4);
        Vehicle vehicle2 = new Vehicle("Reliant", "Robin", 3);
        Vehicle vehicle3 = new Vehicle("Honda", "Fireblade", 2);

        System.out.println(vehicle1);
        System.out.println(vehicle2);
        System.out.println(vehicle3);
    }
}

Answer 1

在我看来，你最好将汽车和自行车分成两个单独的类“汽车”和“自行车”，然后创建一个第三类来容纳这些对象的集合，这样你就可以使用 List 或 ArrayList 来存储它们，并有一个方法可以将它们打印出来。

import java.util.ArrayList;

Public Class Garage
{
   private ArrayList<Vehicle> vehicles;

   Public Garage()
   {
     vehicles = new ArrayList<Vehicle>();
   }

   public void addVehicle(Vehicle v)
   {
      vehicles.add(v);
   }

   public void getVehicles()
   {
     for(Vehicle v : vehicles)
     {
       System.out.Println(v.getModel());
     }
   }
}

您会注意到 ArrayList 接受车辆类型的对象，汽车和自行车都扩展了车辆，因此它们都会被接受。