Java - 如何使用 setter 和 getter 根据另一个参数设置一个参数？

Question

大家早上好!

我想知道如何解决这个问题。问题如下:

我在这里遇到的问题是，我需要从 CarRental.java 获取的参数之一基于另一个参数的设置。在本例中，它是“dailyFee”，它基于“大小”。我完全不知道如何从驱动程序类中设置“dailyFee”，因为到目前为止我不知道如何对其进行编码，以便将其设置为 if 语句中的数字之一。

我的代码(当然不完整):

CarRental.java

import javax.swing.JOptionPane;

public class CarRental 
{
private String name;
private String zipCode;
private String size;
private double dailyFee;
private int rentalDays;
private double totalFee;

public CarRental(String name, String zipCode, String size, double dailyFee, int rentalDays, double totalFee)
{
    this.name = name;
    this.zipCode = zipCode;
    this.size = size;
    if (size.equals("e"))
    {
        dailyFee = 29.99;
    }
    else if (size.equals("m"))
    {
        dailyFee = 38.99;
    }
    else if (size.equals("f"))
    {
        dailyFee = 43.50;
    }
    this.dailyFee = dailyFee;
    this.rentalDays = rentalDays;
    totalFee = dailyFee * rentalDays;
    this.totalFee = totalFee;
}

public CarRental(){}

public void display()
{
    JOptionPane.showMessageDialog(null, "Luxury car for " + name + " from zip code " + zipCode + "\n"
            + "Type = " + size + "\n"
            + "Daily Fee = " + dailyFee + "\n"
            + "Days = " + rentalDays + "\n"
            + "Your rental is $" + totalFee);
}

//includes getters and setters but I didn't include this in this post

UserCarRental.java(驱动程序类)

import javax.swing.JOptionPane;

public class UseCarRental 
{

    public static void main(String[] args) 
    {
        CarRental userInfo = new CarRental();

        userInfo.setName(JOptionPane.showInputDialog("Enter name"));
        userInfo.setZipCode(JOptionPane.showInputDialog("Enter zip code"));
        userInfo.setSize(JOptionPane.showInputDialog("Enter type of car" + "\n" + "e - economy" + "\n" + "m - midsize" + "\n" + "f - full" + "\n" + "l - luxury"));

        userInfo.setRentalDays(Integer.parseInt(JOptionPane.showInputDialog("Enter days to rent")));

        System.out.println(userInfo.getDailyFee());

        userInfo.display();

    }
}

任何帮助将不胜感激!

Answer 1

更改构造函数以仅接受用户输入:

public CarRental(String name, String zipCode, String size,  int rentalDays)
{
    this.name = name;
    this.zipCode = zipCode;
    this.size = size;
    if (size.equals("e"))
    {
        dailyFee = 29.99;
    }
    else if (size.equals("m"))
    {
        dailyFee = 38.99;
    }
    else if (size.equals("f"))
    {
        dailyFee = 43.50;
    }
    this.rentalDays = rentalDays;
    this.totalFee = dailyFee * rentalDays;;
}

收集 main 内的本地 String 变量中的信息，将它们传递给带参数的构造函数，即:public CarRental(String name, String zipCode, String size, intrentrentDays)

像这样:

public static void main(String[] args) 
{
    String name = JOptionPane.showInputDialog("Enter name");
    String zip = JOptionPane.showInputDialog("Enter zip code");
    String size = JOptionPane.showInputDialog("Enter type of car" + "\n" + "e - economy" + "\n" + "m - midsize" + "\n" + "f - full" + "\n" + "l - luxury");
    int days = Integer.parseInt(JOptionPane.showInputDialog("Enter days to rent"))

    CarRental userInfo = new CarRental(name, zip, size, days);

    System.out.println(userInfo.getDailyFee());

    userInfo.display();

}