java - 我的代码无法输出汽车尺寸和总费用，我在试图找到问题时失去了理智

Question

这个问题已经有答案了:

Scanner is skipping nextLine() after using next() or nextFoo()? (25 个回答)

已关闭 6 年前。

我有一项作业，并且我完成了它的代码，但问题仍然是，当我运行它时，汽车类型和总费用在最后显示为空白，这与继承有关，这对于继承来说是新的东西我和我希望我做对了。该计划分为 3 个独立的类(class)，任何帮助将不胜感激

import java.util.*;
public class UseCarRental {
public static void main(String[] args) 
{
       Scanner input = new Scanner(System.in);
        System.out.println("How many days do you need the rental?");
        int rentalLength = input.nextInt();
        System.out.println("Enter requested car size:" +
                "\nEconomy" + "\nMidsize" + "\nFullsize" + "\nLuxury");
        String rentalCarSize = input.nextLine();
        input.next();
        CarRental firstRental = new CarRental(rentalLength, rentalCarSize);
        firstRental.display();
        }

}

class CarRental {
    public  String  rentalCarSize = "";
    public  double rentalFeeDaily;
    public  int rentalLength = 0;
    public  double  rentalFeeTotal= rentalFeeDaily*rentalLength;
    public CarRental(int days, String carSize)
    {
        rentalCarSize   = carSize;
        rentalLength    = days;
    }
    public void display()
    {
        System.out.println(
                "#############" +
                "\nCar Size      = " + getRentalCarSize() +
                "\nRental Length = " + rentalLength +
                "\nTotal Fee     = " + rentalFeeTotal
                );
    }        
    public void setRentalLength(int length)
    {
        rentalLength = length;
    }
    public String getRentalCarSize()
    {
        return rentalCarSize;
    }
    public int getRentalLength()
    {
        return rentalLength;
    }
    public double getRentalFeeTotal()
    {
        return rentalLength * rentalFeeDaily;
    }
    public double getRentalFeeDaily(String carSize)
    {
        switch (carSize)
        {
            case "Economy":
                rentalFeeDaily = 29.99;
                break;
            case "Midsize":
                rentalFeeDaily = 38.99;
                break;
            case "Fullsize":
                rentalFeeDaily = 43.50;
                break;
            case "Luxury":
                rentalFeeDaily = 79.99;
                break;
        }
         return rentalFeeDaily;
        }

    }

import javax.swing.*;
public class LuxuryCarRental extends CarRental
{

 public LuxuryCarRental(int days, String carSize)
    {
        super(days, carSize);
    }

    @Override
    public void display()
    {
        JOptionPane.showMessageDialog(null,
            "\nCar Size      = " + getRentalCarSize() +
            "\nRental Fee    = " + rentalFeeDaily +
            "\nRental Length = " + rentalLength +
            "\nTotal Fee     = " + rentalFeeTotal);
    }
}

Answer 1

在构造函数中设置值后，您永远不会计算rentalFeeTotal。将代码更改为:

class CarRental {
    public          String      rentalCarSize    = "";
    public          double      rentalFeeDaily;
    public          int         rentalLength     = 0;
    public          double      rentalFeeTotal   = 0d;

    public CarRental(int days, String carSize)
    {
        rentalCarSize   = carSize;
        rentalLength    = days;
        rentalFeeTotal   = getRentalFeeDaily(carsize)*rentalLength;

    }

您的代码中还有其他问题:

   Scanner input = new Scanner(System.in);
    System.out.println("How many days do you need the rental?");
    int rentalLength = input.nextInt();
    input.nextLine(); // ADD this line
    System.out.println("Enter requested car size:" +
            "\nEconomy" + "\nMidsize" + "\nFullsize" + "\nLuxury");
    String rentalCarSize = input.nextLine();
    input.next();