Question

好的，刚才问了一个问题而没有提供我所有的代码，愚蠢的想法。这里是。我正在尝试使用带有字符串的if语句来获取成本。无论我做什么，我的成本都会返回为0.请参阅类CarRental，方法getCost。我被告知我可以改变它并使用开关，这很好，但我想知道为什么我正在做的事情无论如何都不起作用，为了知识。

更新：尝试将其更改为开关，结果相同。

import java.util.*;

public class UseCarRental {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("Thank you for choosing ICT car Rentals\n"
                + "Pleae enter your full name:");
        String renterName = input.nextLine();
        System.out.println("Please enter your zip code:");
        int renterZipcode = input.nextInt();
        input.nextLine();
        System.out.println("Please enter the size car you would like:\n"
                + "economy\n"
                + "midsize\n"
                + "fullsize\n"
                + "luxury?");
        String carSize = input.next();
        System.out.println("How many days do you wish to rent this?");
        int rentalDays = input.nextInt();

        if (carSize.equals("luxury")) {
            System.out.println("Will you be wanting a chauffer (y or n");
            String chauffer = input.next();
            LuxuryCarRental rentIt = new LuxuryCarRental(renterName, 
            renterZipcode, carSize, rentalDays,chauffer);
            rentIt.display();
        } else {
            CarRental rentIt = new CarRental(renterName, renterZipcode, 
            carSize, rentalDays);
            rentIt.display();
        }




    } //  end main method
}  //end class UseCarRental

class CarRental {

    private int days;
    private int zip;
    private double cost;
    private String size;
    private double total;
    private String name;

        CarRental(String renterName, int renterZipcode, String carSize, int rentalDays){
            this.days = rentalDays;
            this.zip = renterZipcode;
            this.name = renterName;
            this.size = carSize;
        }

        double getCost(){
            if(size.equals("economy")){
                cost = 29.99;
            }
            if(size.equals("midsize")){
                cost = 38.99;
            }
            if(size.equals("fullsize")){
                cost = 43.50;
            }
            return cost;
        } 

        void display(){
            System.out.println("Thank you for using our service.");
            System.out.println("Your order is as follows:");
            System.out.println("Name: " + name);
            System.out.println("Zip code: " + zip);
            System.out.println("Car size: " + size);
            System.out.println("Cost per day: " + cost);
            System.out.println("Days requested: " + days);
            total = days * cost;
            System.out.println("Total cost: " + total);
            System.out.println("If any of the above information is incorrect, too bad bud, because it isn't.");
        }

}

class LuxuryCarRental extends CarRental {

    private int chauffer = 200;
    private int days;
    private int zip;
    private double cost;
    private String size;
    private double total;
    private String name;

    LuxuryCarRental(String renterName, int renterZipcode, String carSize, int rentalDays, String chauffer){
        super(renterName, renterZipcode, carSize, rentalDays);
        this.days = rentalDays;
        this.zip = renterZipcode;
        this.name = renterName;
        this.size = carSize;
    }

    @Override
    void display(){
            System.out.println("Thank you for using our service.");
            System.out.println("Your order is as follows:");
            System.out.println("Name: " + name);
            System.out.println("Zip code: " + zip);
            System.out.println("Car size: Luxury");
            System.out.println("Cost per day: " + cost);
            System.out.println("Days requested: " + days);
            System.out.println("Chauffer cost: " + chauffer);
            total = days * cost + chauffer;
            System.out.println("Total cost: " + total);
            System.out.println("If any of the above information is incorrect, too bad bud, because it isn't.");
        }
}

Answer 1

您没有在代码中调用getCost方法。

Answer 2

display方法从cost中名为LuxuryCarRental的实例变量中获取“每日费用”。您的代码都没有为该字段分配任何内容，因此（当然！）它始终为零。

如果语句使用字符串

2 个答案: