Java 使用构造函数和获取另一个类的方法时出现问题
因此，当我试图运行user类时，我不断地得到错误，说double是必需的，并且找不到参数。我在第17、40、42、44、46和48行发现了错误。这些都是错误，都说需要双倍。请用简单的英语回答 我的主要班级：Java 使用构造函数和获取另一个类的方法时出现问题,java,constructor,Java,Constructor,因此，当我试图运行user类时，我不断地得到错误，说double是必需的，并且找不到参数。我在第17、40、42、44、46和48行发现了错误。这些都是错误，都说需要双倍。请用简单的英语回答 我的主要班级： import java.util.Scanner; public class ElectricityCalculatorUser { //Main method public static void main (String [] args) { El
import java.util.Scanner;
public class ElectricityCalculatorUser {
//Main method
public static void main (String [] args) {
ElectricityCalculator myCalculator = new ElectricityCalculator();
Scanner input = new Scanner (System.in);
//Input the initial reading
double initialReading;
System.out.print ("What is the inital reading on your electricity meter in kwH? ");
initialReading = input.nextDouble ();
//Input the final reading
double finalReading;
System.out.print ("What is the final reading on your electricity meter in kwH? ");
finalReading = input.nextDouble ();
//Input the number of days
//between readings
double numberOfDays;
System.out.print ("How many days have passed between your initial and final reading? ");
numberOfDays = input.nextDouble ();
//Calculations
double totalElectricityUsed = myCalculator.totalElectricityUsed();
System.out.print ("Total electricity used = " + totalElectricityUsed);
double costOfElectricity = myCalculator.costOfElectricity();
System.out.print ("Cost of electricity = " + costOfElectricity);
double standingCharge = myCalculator.standingCharge();
System.out.print ("Standing charge = " + standingCharge);
double costBeforeVAT = myCalculator.costBeforeVAT();
System.out.print ("Cost before VAT is added = " + costBeforeVAT);
double VAT = myCalculator.VAT();
System.out.print ("Cost of VAT = " + VAT);
double totalCost = myCalculator.totalCost();
System.out.print ("Total cost = " + totalCost);
}
}
public class ElectricityCalculator {
//Attributes
private double initialReading;
private double finalReading;
private double numberOfDays;
//Constructors
public ElectricityCalculator (double ir, double fr, double nod) {
initialReading = ir;
finalReading = fr;
numberOfDays = nod;
}
//Calculating total electricity used
public double totalElectricityUsed () {
return finalReading - initialReading;
}
//Calculating cost of electricity
public double costOfElectricity () {
return totalElectricityUsed * 0.175;
}
//Calculating standing charge
public double standingCharge (double numberOfDays) {
return numberOfDays * 0.25;
}
//Calculating cost before VAT is added
public double costBeforeVAT (double costOfElectricity, double standingCharge) {
return costOfElectricity + standingCharge;
}
//Cost of VAT
public double VAT (double costBeforeVAT) {
return costBeforeVAT * 0.05;
}
//Total cost of electricity used
//including VAT
public double totalCost (double costBeforeVAT, double VAT) {
return costBeforeVAT + VAT;
}
}
在java中，如果不编写构造函数，将自动为您添加一个默认构造函数，该构造函数将是
publicpublic ElectricityCalculator () {
}
public ElectricityCalculator (double ir, double fr, double nod) {
initialReading = ir;
finalReading = fr;
numberOfDays = nod;
}
ElectricityCalculator myCalculator = new ElectricityCalculator();
ElectricityCalculator myCalculator = new ElectricityCalculator(initialReading, finalReading, numberOfDays);
在java中，如果不编写构造函数，将自动为您添加一个默认构造函数，该构造函数将是
publicpublic ElectricityCalculator () {
}
public ElectricityCalculator (double ir, double fr, double nod) {
initialReading = ir;
finalReading = fr;
numberOfDays = nod;
}
ElectricityCalculator myCalculator = new ElectricityCalculator();
ElectricityCalculator myCalculator = new ElectricityCalculator(initialReading, finalReading, numberOfDays);
除了Sleiman Jneidi answer，您正在调用函数，但不提供任何参数，因为方法定义要求：
double standingCharge = myCalculator.standingCharge();
double standingCharge = myCalculator.standingCharge(10.0); //example for 10 days
代码第42行、第44行、第46行和第48行中存在相同的问题除了Sleiman Jneidi answer之外，您正在调用函数，但不提供任何参数，正如方法定义所要求的：
double standingCharge = myCalculator.standingCharge();
public ElectricityCalculator (double ir, double fr, double nod);
public double standingCharge (double numberOfDays);
public double costBeforeVAT (double costOfElectricity, double standingCharge);
public double VAT (double costBeforeVAT);
public double totalCost (double costBeforeVAT, double VAT);
double standingCharge = myCalculator.standingCharge(10.0); //example for 10 days
public ElectricityCalculator (double ir, double fr, double nod);
public double standingCharge (double numberOfDays);
public double costBeforeVAT (double costOfElectricity, double standingCharge);
public double VAT (double costBeforeVAT);
public double totalCost (double costBeforeVAT, double VAT);
ElectricityCalculator myCalculator = new ElectricityCalculator();
// pass arguments here
// v v v
... = new ElectricityCalculator( initialReading , finalReading , numberOfDays );
VAT（…）costBeforeVATcostBeforeVAT（…，…）public double standingCharge () {
return numberOfDays * 0.25;
}
numberOfDaysElectricityCalculatorpublic double costBeforeVAT () {
return costOfElectricity() + standingCharge();
}
ElectricityCalculator myCalculator = new ElectricityCalculator();
// pass arguments here
// v v v
... = new ElectricityCalculator( initialReading , finalReading , numberOfDays );
VAT（…）costBeforeVATcostBeforeVAT（…，…）public double standingCharge () {
return numberOfDays * 0.25;
}
numberOfDaysElectricityCalculatorpublic double costBeforeVAT () {
return costOfElectricity() + standingCharge();
}
相关：。那么，我该如何修复代码，使其基本上按我想要的方式运行呢？对编程来说非常陌生，所以我不太理解你的答案。@John我已经编辑了答案，现在应该很清楚了。那么我该如何修复代码，使其基本上按照我想要的方式运行呢？对编程非常陌生，所以我不太理解你的答案。@John我编辑了答案，现在应该很清楚了，但我希望用户输入主方法中的3个值，然后从中计算出所有其他方法。这就是为什么需要使用参数化构造函数
ElectricityCalculator myCalculator=new ElectricityCalculator（初始读数、最终读数、天数）但我希望用户输入主方法中的3个值，然后从中计算出所有其他方法。这就是为什么需要使用参数化构造函数ElectricityCalculator myCalculator=new ElectricityCalculator（初始读数、最终读数、天数）