給与計算

Question

私は私の入力に接続するたびに、それは私にエラー与える：スレッドで

例外Calculate.calculatePayで "メイン" のjava.lang.NullPointerException

（Calculate.java:13）

を

at Hours.main（Hours.java:30）

このエラーはなぜ発生するのですか？

これはHours.javaです：

import java.util.Scanner; 

public class Hours { 

    public static void main(String[] args) { 

     Scanner input = new Scanner(System.in); 
     Calculate hours = new Calculate(); 
     Bills hours1 = new Bills(); 

     System.out.println("Enter your hours for this week: "); 
     int Weekhours = input.nextInt(); 

     System.out.println("Enter the number of days you work this week: "); 
     int Days = input.nextInt(); 
     int new_days = (Days - 1); 

     System.out.println("Enter your hourly wage: "); 
     double Wage = input.nextDouble(); 

     System.out.println("Did you work Sunday? <yes/no> "); 
     String Didworksun = input.nextLine(); 

     System.out.println("How much money do you have saved already? "); 
     int Money = input.nextInt(); 

     System.out.println("How much is your bills this month? "); 
     int Monthpayment = input.nextInt(); 

     hours.calculatePay(Weekhours, Wage, Days, new_days); 
     hours1.bills(Monthpayment, Money); 
     hours.displayHours(); 

     System.out.println(); 

} 

}

そしてこれはCalculate.javaです：

import java.util.Scanner; 

public class Calculate { 
public int Weekhours, Days, new_days; 
public double pay, Wage, payment, weekpay, Sundaypay, premium; 
public String Didworksun, Night; 

Scanner input = new Scanner(System.in); 

public double calculatePay(int Weekhours, double Wage, int Days, int new_days) { 


    if (Didworksun.equals("y") || Didworksun.equals("Y") || Didworksun.equals("yes") || Didworksun.equals("Yes") || Didworksun.equals("YworkES") || Didworksun.equals("YeS") || Didworksun.equals("yEs") || Didworksun.equals("yeS") || Didworksun.equals("YEs") || Didworksun.equals("yES")) { 

     System.out.println("How many hours did you work on sunday? "); 
     double Sundayhours = input.nextDouble(); 

     System.out.println("You worked " + (Sundayhours) + (" hours on Sunday.")); 

     double Sundaywage = (Wage * 1.5); 
     double Sundaypay = (Sundayhours * Sundaywage); 
     double new_hours = (Weekhours - Sundayhours); 
     double weekpay = (new_hours * Wage); 
     int Worksunday1 = 1; 

     System.out.println("How much is night premium? "); 
     double Premcash = input.nextDouble(); 

     double premium = (Premcash * (Days + Worksunday1)); 

     pay = Sundaypay + weekpay + premium; 

     double taxes = .21; 
     double tax_payment = pay * taxes; 

     payment = (pay - tax_payment); 


}else if (Didworksun.equals("n") || Didworksun.equals("N") || Didworksun.equals("no") || Didworksun.equals("No") || Didworksun.equals("NO") || Didworksun.equals("nO")) { 
    System.out.println("You did not work Sunday."); 

    int new_hours = Weekhours; 
    double weekpay = (new_hours * Wage); 


    System.out.println("How much is night premium? "); 
    double Premcash = input.nextDouble(); 

    double premium = (Premcash * Days); 

    double taxes = .21; 
    double tax_payment = pay * taxes; 
    pay = weekpay + premium; 
    payment = (pay - tax_payment); 

} else { 
    System.out.println("Error: Invalid response. Try again"); 
     return calculatePay(Weekhours, Wage, Days, new_days); 

} 
    return payment; 


}public void displayHours() { 
    System.out.printf(" /nYour paycheck will be: %f", payment); 
} 

} 

Bills.java

は

import java.util.Scanner; 
public class Bills extends Calculate { 

private int Money; 
private int Monthpayment; 
public void bills(int Monthpayment, int Money) { 

Scanner input = new Scanner(System.in); 

double until = (Monthpayment - (Money + payment)); 

if (until <= 0) { 

    System.out.println("You're able to make your payment"); 

} else { 

    System.out.println("You need to save " + until + (" more dollars to make your payment")); 

} 


} 


} 

Answer 1

Didworksunもありますin Calculateは初期化されません。あなたはそれを使用することができます前に、何かにDidworksunを設定する必要が

if (Didworksun.equals("y") || Didworksun.equals("Y")

。