Java层次结构和对象数组

Question

对于我为学校项目编写的这段代码，我有很多问题。我试图这样做：

创建和实现一个类的层次结构，其中Vehicle超类和'摩托车'和'卡车'是子类。

• 摩托车和卡车的共同点是变量车轮和重量以及方法显示（）。这些属性不应该在课堂外访问。 display（）将打印出轮子和重量，只能通用于普通类和所有的子类。
• 摩托车级别独有的数据应该是乘客。 Truck类独有的数据应该是有效载荷。包含显示此信息的方法。
• 绘制类层次结构。
• 创建一个'驱动程序'类来测试您的层次结构。允许用户通过将引用存储在Vehicle数组中来创建多个对象。您应该允许用户通过输入'm'来创建摩托车对象，然后询问相关属性。沿着相同的路线，使用't'来创建卡车对象。
• 输入完所有数据后，通过调用display（）方法打印出每个对象的内容。在卡车的情况下打印摩托车或载荷的人数。需要注意的是display（）方法将被覆盖了不同的子类

这里是我的代码原油：

import java.util.Scanner; 
class Hierarchy{ 
    public static void main(String[] args){ 
     Scanner in = new Scanner(System.in); 
     Vehicle [] garage = new Vehicle [3]; 
     for(int i = 0; i< garage.length;i++){ 
      System.out.println("Please enter 't' to create a truck, and 'm' for a motorcycle"); 
      String charIn = in.nextLine(); 
      if(charIn == "m"){ 
       System.out.println("What is the payload of the Truck"); 
       int payload = in.nextInt(); 
       System.out.println("What is the weight of the Truck"); 
       int weight = in.nextInt(); 
       System.out.println("How many wheels does the Truck have"); 
       int wheels = in.nextInt(); 
       garage[i] = new Truck(payload, wheels, weight); 
      }else{ 
       System.out.println("How many passengers can the Motorcycle seat"); 
       int passengers = in.nextInt(); 
       System.out.println("What is the weight of the Motorcycle"); 
       int weight = in.nextInt(); 
       System.out.println("How many wheels does the Motorcycle have"); 
       int wheels = in.nextInt(); 
       garage[i] = new Motorcycle(passengers, weight, wheels); 
      } 
     } 
     //display(); 
    } 
} 


class Vehicle{ 
    int wheels; 
    int weight; 
    public Vehicle(int wheels, int weight){ 
     weight = this.weight; 
     wheels = this.wheels; 
    } 
    //private void display(int weight, int passengers, int wheels){ 
    //} 
    //private void display(int weight, int payload, int wheels){ 
    //} 

} 

class Truck extends Vehicle{ 
    int payload; 
    public int getWheels(){ 
     return wheels; 
    } 
    public int getWeight(){ 
     return weight; 
    } 
    public Truck(int wheels, int payload, int weight){ 
     super(wheels, weight); 
     this.payload = payload; 
    } 
} 

class Motorcycle extends Vehicle{ 
    int passengers; 
    public int getWheels(){ 
     return wheels; 
    } 
    public int getWeight(){ 
     return weight; 
    } 
    public Motorcycle(int wheels, int passengers, int weight){ 
     super(wheels, weight); 
     this.passengers = passengers; 
    } 
} 

我在尽可能多的资源试图寻找周围尽我所能，但我看不到将数据输入到超类和子类中的方法，然后将信息放入一个对象（车库数组）中。另外，任何人都可以给我一些方法来打印车库数组的对象中的数据？当然，如果你看到任何愚蠢的错误，随时告诉我。 非常感谢您的帮助！

Answer 1

开始下列要求：

class Vehicle { 
    int wheels; 
    int weight; 
    public Vehicle(int wheels, int weight){ 
     this.weight = weight; 
     this.wheels = wheels; 
    } 

    public int getWheels() { 
     return wheels; 
    } 

    public int getWeight() { 
     return weight; 
    } 
} 

class Truck extends Vehicle { 
    int payload; 

    public Truck(int wheels, int payload, int weight){ 
     super(wheels, weight); 
     this.payload = payload; 
    } 

    public String toString() { 
     // todo - write code to output the truck details as a string 
     return "truck details here"; 
    } 
} 

class Motorcycle extends Vehicle{ 
    int passengers; 

    public Motorcycle(int wheels, int passengers, int weight){ 
     super(wheels, weight); 
     this.passengers = passengers; 
    } 

    public String toString() { 
     // todo - write code to output the motorcycle details as a string 
     return "motorcycle details here"; 
    } 
} 

你的代码来创建卡车和摩托车，并把它们放到车阵看起来很好。

当你想打印出来，只是数组调用每个对象的toString并打印出来throught循环：

for(Vehicle vehicle : garage) { 
    System.out.println(vehicle.toString()); 
} 

此外，您测试是否charIn == 'm'但你创建一个卡车，而不是摩托车。如果用户输入除m以外的任何东西，则您创建一辆摩托车。