如何用Java中的用户输入填充构造函数？

Question

我在作业上碰壁，一直在梳理网站以寻求任何有用的信息（出现空白）。我需要创建一个类，在该类中创建一个构造函数，然后再创建一个子类以扩展超类。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。从概念上来说没问题。

我的问题是：如何使用构造函数初始化对象，但需要用户输入？

现在我得到的错误是：“类CarRental中的构造函数CarRental无法应用于给定类型；必需：String，int，String，int找到：无参数原因：实际和正式参数列表的长度不同”

请不要对“错误告诉您问题出在哪里”发表任何评论。不，它没有告诉 我 它是什么。我是这个东西的小宝贝，需要一点点握力。

我将在下面粘贴我的3个班级。因为我真是个新手，它们可能会让您痛苦不已（而且，我的课程是8周的简短课程，实际上没有时间专门用于伪代码，因此我对逻辑本身也有额外的挑战）。

我并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。

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 ....

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：

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，主要是试图使对象实例化起作用）

谢谢你的帮助！！

Answer 1

在main方法中创建局部变量，例如String和int变量，然后在用用户输入填充这些变量之后，使用它们来调用构造函数。

我将发布一个一般示例，由于这是家庭作业，因此最好向您展示概念，然后让 您 使用该概念来创建代码：

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);    
}