Question

我对于为学校项目撰写的这段代码有很多疑问。我想这样做：

创建并实现一个类层次结构，其中Vehicle超类和＆＃39; Motorcycle＆＃39;和卡车＆＃39;是子类。

摩托车和卡车的共同点是变量轮和重量以及方法显示（）。这些属性不应该在课外访问。 display（）将打印出轮子和重量，并且只能由公共类和所有子类访问。
摩托车类特有的数据应该是乘客。 Truck类特有的数据应该是有效载荷。包括显示此信息的方法。
绘制类层次结构。
创建一个＆＃39;驱动程序＆＃39;用于测试层次结构的类。允许用户通过将引用存储在Vehicle数组中来创建多个对象。您应该允许用户输入＆＃39; m＆＃39;来创建摩托车对象，然后询问相关属性。同样，使用＆＃39;＃39;创建卡车对象。
输入所有数据后，通过调用display（）方法打印出每个对象的内容。如果是卡车，则打印摩托车或有效载荷的乘客数量。请注意，必须为不同的子类重写display（）方法

这是我粗略的代码：

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;
    }
}

我尝试过尽可能多的资源，但我无法看到将数据输入超类和子类的方法，然后将信息放入一个对象（车库数组））。另外，任何人都可以给我一些方法来打印出车库阵列对象中的数据吗？当然，如果你看到任何愚蠢的错误，请随时告诉我。非常感谢您的帮助！

Answer 1

从以下开始：

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";
    }
}

您创建卡车和摩托车并将其放入车辆阵列的代码看起来很不错。

当你想要打印出来时，只需循环调用每个对象上的toString数组并打印出来：

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

此外，您测试是否charIn == 'm'但是您创建的是卡车而不是摩托车。如果用户输入m以外的任何内容，则可以创建摩托车。

Java层次结构和对象数组

1 个答案: