Java層次結構和對象數組

Question

對於我爲學校項目編寫的這段代碼，我有很多問題。我試圖這樣做：

創建和實現一個類的層次結構，其中Vehicle超類和'摩托車'和'卡車'是子類。

• 摩托車和卡車的共同點是變量車輪和重量以及方法顯示（）。這些屬性不應該在課堂外訪問。 display（）將打印出輪子和重量，只能通用於普通類和所有的子類。
• 摩托車級別獨有的數據應該是乘客。 Truck類獨有的數據應該是有效載荷。包含顯示此信息的方法。
• 繪製類層次結構。
• 創建一個'驅動程序'類來測試您的層次結構。允許用戶通過將引用存儲在Vehicle數組中來創建多個對象。您應該允許用戶通過輸入'm'來創建摩托車對象，然後詢問相關屬性。沿着相同的路線，使用't'來創建卡車對象。
• 輸入完所有數據後，通過調用display（）方法打印出每個對象的內容。在卡車的情況下打印摩托車或載荷的人數。需要注意的是display（）方法將被覆蓋了不同的子類

這裏是我的代碼原油：

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; 
    } 
} 

我在儘可能多的資源試圖尋找周圍盡我所能，但我看不到將數據輸入到超類和子類中的方法，然後將信息放入一個對象（車庫數組）中。另外，任何人都可以給我一些方法來打印車庫數組的對象中的數據？當然，如果你看到任何愚蠢的錯誤，隨時告訴我。 非常感謝您的幫助！

Answer 1

開始下列要求：

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"; 
    } 
} 

你的代碼來創建卡車和摩托車，並把它們放到車陣看起來很好。

當你想打印出來，只是數組調用每個對象的toString並打印出來throught循環：

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

此外，您測試是否charIn == 'm'但你創建一個卡車，而不是摩托車。如果用戶輸入除m以外的任何東西，則您創建一輛摩托車。