java - 如何在构造函数中传递参数？

Question

我正在做一个简单的 Java 作业。看来我的语法和逻辑都是正确的。但是，构造函数无法理解我尝试传入的参数，这就是为什么所有计算都是错误的。我已附上输出。有人知道如何解决这个问题吗？任何帮助将不胜感激。谢谢!

public class DT_CarStats
 {
   private double gallons;
   private double mpg;
   private double ppg;

public DT_CarStats(double gallons, double mpg, double ppg)
{
  gallons = gallons;
  mpg = mpg;
  ppg = ppg;
}

public double CostPer100()
{ 
  return 100 / (mpg * ppg);
}

public double MaxDistance()
{
  return mpg * gallons;
}
}

import java.util.Scanner;

public class DT_CarStatsTester
{
  public static void main(String[] args)
  {
    Scanner scannerObject = new Scanner(System.in);
    double gallons, mpg, ppg;
    System.out.printf("******************************************* \n");
    System.out.printf("* Welcome to my Distance to Empty App  * \n");
    System.out.printf("******************************************* \n");
    System.out.printf("Please enter the number of gallons of gas in the     tank: ");
    gallons = scannerObject.nextDouble();
    System.out.printf("Please enter the fuel efficiency (miles per gallon): ");
    mpg = scannerObject.nextDouble();
    System.out.printf("Please enter the price of gas per gallon: ");
    ppg = scannerObject.nextDouble();
    DT_CarStats cs = new DT_CarStats(gallons,mpg,ppg);
    System.out.printf("\n");
    System.out.printf("To drive 100 miles, it will cost $" + cs.CostPer100() + ". \n");
    System.out.printf("The car can currently drive a maximum of " + cs.MaxDistance() + " miles. \n");
    System.out.printf("******************************************* \n");
    System.out.printf("* Thanks for using our App, Safe Travels! * \n");
    System.out.printf("******************************************* \n");
  }
}

示例运行:

******************************************* 
******************************************* 
* Welcome to my Distance to Empty App  * 
******************************************* 
Please enter the number of gallons of gas in the tank: 17.6
Please enter the fuel efficiency (miles per gallon): 24.8
Please enter the price of gas per gallon: 2.36

To drive 100 miles, it will cost $Infinity. ==> This is wrong, should be $9.52 
The car can currently drive a maximum of 0.0 miles. ==> This should be 436.48 miles
******************************************* 
* Thanks for using our App, Safe Travels! * 
******************************************* 

Answer 1

使用 this 指定您指的是类字段，而不是构造函数参数，因为它们的名称相同。

public DT_CarStats(double gallons, double mpg, double ppg)
{
  this.gallons = gallons;
  this.mpg = mpg;
  this.ppg = ppg;
}