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我应该制作一个具有MotorVehicle抽象类的程序。Car, Truck,Van是种MotorVehicle。setTerms()和displayInfo()是唯一的抽象。Car有String transTypeand void Car(), Vanhas int numPassengerand void Van(), as Truckhas double payLoadand void Truck().

输出应该是这样的：

品牌是马自达

车辆类型是轿车

颜色是红色

传输类型为自动

价格为 840000.0

条款是5年支付

品牌是五十铃

车辆类型是卡车

颜色是白色

有效载荷容量为 3.5

价格为 910000.0

条款是3年支付

品牌是三菱

车辆类型是家庭面包车

颜色是蓝色

乘客人数为 8

价格为 1050000.0

条款是 7 年支付

但是我的程序仍然没有产生这个输出

这是我当前的代码：

public abstract class MotorVehicle
{
    private String vehicleType;
    private String brand;
    private String color;
    private String terms;

    public MotorVehicle(String vcl, String brn, String clr, String trm)
    {
        vehicleType = vcl;
        brand = brn;
        color = clr;
        terms = trm;
    }

    public String getVehicleType()
    {
        return vehicleType;
    }

    public String getBrand()
    {
        return brand;
    }

    public String getColor()
    {
        return color;
    }

    public abstract void setTerms();

    public abstract void displayInfo();

}

//=========================================

public class Car extends MotorVehicle
{
    String transType="";
    String vehicleType;
        String brand;
    String color;
    String terms;
    int price = 0;

    public Car(String vcl, String brn, String clr, String trm)
    {
        super(vcl, brn, clr, trm);
        vehicleType = vcl;
        brand = brn;
        color = clr;
        terms = trm;
    }

    public void Car()
    {
        brand = "Mazda";
        vehicleType = "Sedan";
        color = "Red";
        transType = "Automatic";
        price = (int) (700000 + (700000*0.2));
        Double.toString(price);
        terms = "5";   
    }

    public void setTerms()
    {
         return;
    }

    public void displayInfo()
    {
        System.out.println("Brand is " + brand);
        System.out.println("Vehicle type is " + vehicleType);
        System.out.println("Color is " + color);
        System.out.println("Transmission type is " + transType);
        System.out.println("Price is " + price);
        System.out.println("Terms is " + terms + " years to pay");
    }

}

//=================================

public class Truck extends MotorVehicle
{
    double payLoad=0.0;
    String vehicleType;
        String brand;
    String color;
    String terms;
    int price = 0;

    public Car(String vcl, String brn, String clr, String trm)
    {
        super(vcl, brn, clr, trm);
        vehicleType = vcl;
        brand = brn;
        color = clr;
        terms = trm;
    }

    public void Truck()
    {
        brand = "Isuzu";
        vehicleType = "Truck";
        color = "White";
        payLoad = 3.5;
        Double.toString(payLoad);
        price = (int) (700000 + (700000*0.3));
        Double.toString(price);
        terms = "3";     
    }

    public void setTerms()
    {
         return;
    }

    public void displayInfo()
    {
        System.out.println("Brand is " + brand);
        System.out.println("Vehicle type is " + vehicleType);
        System.out.println("Color is " + color);
        System.out.println("Payload capacity is " + payLoad);
        System.out.println("Price is " + price);
        System.out.println("Terms is " + terms + " years to pay");
    }   


 }

//==========================

public class Van extends MotorVehicle
{
    int numPassenger=0;
    String vehicleType;
        String brand;
    String color;
    String terms;
    int price=0;

    public Van(String vcl, String brn, String clr, String trm)
    {
            super(vcl, brn, clr, trm);
        vehicleType = vcl;
        brand = brn;
        color = clr;
        terms = trm;
    }

    public void Van()
    {
    brand = "Mitsubishi";
    vehicleType = "Family Van";
    color = "Blue";
    numPassenger = 8;
    String.valueOf(numPassenger);
    price = (int) (700000 + (700000*0.5));
    Double.toString(price);
    terms = "7";   
}

public void setTerms()
{
     return;
}

public void displayInfo()
{
    System.out.println("Brand is " + brand);
    System.out.println("Vehicle type is " + vehicleType);
    System.out.println("Color is " + color);
    System.out.println("Number of passenger is " + numPassenger);
    System.out.println("Price is " + price);
    System.out.println("Terms is " + terms + " years to pay");
}

}

//===================

这是主程序：

public class MainVehicle 
{
    public static void main(String[] args)
    {
        BBVehicle[] vhl= new BBVehicle[3];

        int ctr=0;
        while(ctr<3)
        {
            if (ctr==0)
                vhl[ctr]=new Car();
            else if(ctr==1)
                vhl[ctr]= new Truck();
            else
                vhl[ctr]= new Van();
            vhl[ctr].displayInfo();
            ctr++;
        }
     }

}

我不确定我的程序有什么问题。请帮帮我谢谢

4

2 回答 2

2

一世）

public void Car()
public void Truck()
public void Van()

您正在定义类构造函数的返回类型

它应该是

public Car()
public Truck()
public Van()

构造函数类似于实例方法，但它与方法的不同之处在于它没有显式的返回类型，它不是隐式继承的，而且它通常对范围修饰符有不同的规则。

ii）在抽象类中定义一个无参数构造函数（来自评论）

iii)

    BBVehicle[] vhl= new BBVehicle[3];

    int ctr=0;
    while(ctr<3)
    {
        if (ctr==0)
            vhl[ctr]=new Car();

您正在将 Car 类转换为 BBVehicle 类。虽然，这两个类是不同的。这两个类之间没有关系..

于 2013-01-21T13:41:56.373 回答
1

我要给出的第一条建议是你不应该在你的 superlcas 中隐藏你的成员变量。

private在每个子类中，您声明的变量与您在超类中定义的变量同名。相反，您应该简单地从子类中删除重复项，并且：

  1. 将超类中变量的可见性更改为使它们可用于子类的东西（即protected）
  2. displayInfo()利用 getter 在您的方法中访问它们。为此，您需要get[VariableName]() 在超类中设置每个字段。
于 2013-01-21T13:34:27.033 回答