如何使用 Java 中的用户输入填充构造函数? [英] How to populate a constructor with user input in Java?
问题描述
我在一项任务上碰壁了，并一直在梳理网站以寻找任何有用的东西(结果是空的).我需要创建一个类，在该类中创建一个构造函数，然后创建一个子类来扩展超类.然后，我需要使用 main 方法创建一个新文件来演示这两种情况.概念上没问题.
I've hit a wall on an assignment and have been combing the site for anything helpful (came up empty). I'm required to create a class, a constructor within that class, and then a subclass to extend the superclass. Then, I'm required to create a new file with a main method to demonstrate both cases. No problem, conceptually.
我的问题是:如何使用构造函数初始化对象，但使用用户输入?
My question is this: how do I initialize an object using the constructor, but with user input?
现在我得到的错误是:CarRental 类中的构造函数 CarRental 不能应用于给定的类型；必需:字符串，整数，字符串，整数发现:没有参数原因:实际和形式参数列表的长度不同"
Right now the error I'm getting is: "constructor CarRental in class CarRental cannot be applied to given types; required: String,int,String,int found: no arguments reason: actual and formal argument lists differ in length"
请不要对错误告诉您问题出在哪里"进行冷嘲热讽.不，它不会告诉我它是什么.我在这方面是个小宝贝，需要一点帮助.
Please no snide remarks on "the error tells you what the problem is." No, it doesn't tell me what it is. I'm a wee babe in this stuff and need a little hand-holding.
我将在下面粘贴我的 3 个课程.他们可能会让你痛苦不堪，因为我是一个新手(而且，我的课程是一个 8 周的简短课程，几乎没有时间专门用于伪代码，所以我有一个额外的挑战来构思逻辑本身).
I'll paste my 3 classes below. They will probably make you writhe in agony, since I'm such a newb (also, my class is an abbreviated 8-week course where virtually no time was dedicated to pseudocode, so I have the extra challenge of conceiving the logic itself).
我不是在寻找任何人为我做作业，我只是在 UseCarRental.java 文件中寻找帮助.这是我的代码..
I am not looking for anyone to do my homework for me, I am just looking for a helping hand in the UseCarRental.java file. Here's my code..
public class CarRental {
protected String renterName;
protected int zipCode;
protected String carSize;
protected double dailyRate;
protected int rentalDays;
protected double totalCost;
final double ECONOMY = 29.99;
final double MIDSIZE = 38.99;
final double FULLSIZE = 43.50;
public CarRental(String renterName, int zipCode, String carSize, int rentalDays){
totalCost = dailyRate * rentalDays;
}
public String getRenterName(){
return renterName;
}
public void setRenterName(String renter){
renterName = renter;
}
public int getZipCode(){
return zipCode;
}
public void setZipCode(int zip){
zipCode = zip;
}
public String getCarSize(){
return carSize;
}
public void setCarSize(String size){
carSize = size;
}
public double getDailyRate(){
return dailyRate;
}
public void setDailyRate(double rate){
switch (getCarSize()) {
case "e":
rate = ECONOMY;
break;
case "m":
rate = MIDSIZE;
break;
case "f":
rate = FULLSIZE;
break;
}
}
public int getRentalDays(){
return rentalDays;
}
public void setRentalDays(int days){
rentalDays = days;
}
public double getTotalCost(){
return totalCost;
}
public void setTotalCost(double cost){
totalCost = cost;
}
public void displayRental(){
System.out.println("==============================================");
System.out.println("Renter Name: " + getRenterName());
System.out.println("Renter Zip Code: " + getZipCode());
System.out.println("Car size: " + getCarSize());
System.out.println("Daily rental cost: $" + getDailyRate());
System.out.println("Number of days: " + getRentalDays());
System.out.println("Total cost: $" + getTotalCost());
}
}
子类 LuxuryCarRental....
the subclass LuxuryCarRental....
public class LuxuryCarRental extends CarRental {
final double chauffeur = 200.00;
final double dailyRate = 79.99;
protected String chauffeurStatus;
public LuxuryCarRental(String renterName, int zipCode, String carSize, int rentalDays) {
super(renterName, zipCode, carSize, rentalDays);
}
public String getChauffeurStatus(){
return chauffeurStatus;
}
public void setChauffeurStatus(String driver){
chauffeurStatus = driver;
}
public double getChauffeurFee(){
return chauffeur;
}
public void setTotalLuxuryCost(){
if (chauffeurStatus=="y")
setTotalCost((dailyRate * getRentalDays()) + (chauffeur * getRentalDays()));
else
setTotalCost(dailyRate * getRentalDays());
}
@Override
public void displayRental(){
System.out.println("==============================================");
System.out.println("Renter Name: " + getRenterName());
System.out.println("Renter Zip Code: " + getZipCode());
System.out.println("Car size: " + getCarSize());
System.out.println("Optional Chauffeur fee: $" + getChauffeurFee());
System.out.println("Daily rental cost: $" + getDailyRate());
System.out.println("Number of days: " + getRentalDays());
System.out.println("Total cost: $" + getTotalCost());
}
}
现在是带有 main 方法的类:
and now the class with the main method:
import java.util.Scanner;
public class UseRentalCar {
public static void main(String[] args){
Scanner keyboard = new Scanner(System.in);
CarRental rentalCar = new CarRental();
System.out.println("==========================");
System.out.println("RENTAL CAR SELECTION");
System.out.println("==========================");
System.out.println("Enter your name: ");
rentalCar.setRenterName(keyboard.next());
System.out.println("Enter your zip code: ");
rentalCar.setZipCode(keyboard.nextInt());
System.out.println("Enter the car size ("e=Economy, m=Midsize, f=Fullsize: ");
rentalCar.setCarSize(keyboard.next());
System.out.println("Enter the number of days: ");
rentalCar.setRentalDays(keyboard.nextInt());
rentalCar.displayRental();
}
}
(省略了一些无关紧要的原因，主要是为了让对象实例化工作)
(omitted some cause it doesn't matter, mainly trying to get the object instantiation working)
感谢您的帮助！！
推荐答案
在你的 main 方法中创建局部变量，比如 String 和 int 变量，然后在这些变量被用户输入填充后，使用它们来调用构造函数.
Create local variables in your main method, say String and int variables, and then after these variables have been filled with user input, use them to call a constructor.
我将发布一个一般示例，因为这是作业，最好向您展示概念，然后让您使用该概念来创建代码:
I will post a general example, since this is homework, it is better to show you the concept and then let you use the concept to create the code:
public class Foo {
private String name;
private int value;
public Foo(String name, int value) {
this.name = name;
this.value = value;
}
}
别处
import java.util.Scanner;
public class Bar {
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
System.out.print("Please enter name: ");
String name = keyboard.nextLine(); // local variable
System.out.print("Please enter value: " );
int number = keyboard.nextint(); // another local variable
keyboard.nextLine(); // to handle the end of line characters
// use local variables in constructor call
Foo foo = new Foo(name, number);
}
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