Question

我创建了一个业务程序，它通过循环获取双值并计算净利润。我需要将主类的输入值添加到名为Business的自定义类中。然后我应该计算Business类中的净利润并将最终值打印到主类。当我运行当前程序时，结果为“0.0”。 Business类没有从我的主类中获取输入值，但我无法弄清楚原因。主要课程如下：

public class BusinessProject {

public static double revenue;
public static double expenses;
public static double TotalRevenue;
public static double TotalExpenses;

public static void main(String[] args) {

    Business calc = new Business();

    getTotalRevenue();
    getExpense();
    calc.Profit();

}   
public static double getTotalRevenue() {    
    Scanner scan = new Scanner(System.in);

    while (true) {
        System.out.println("Enter your revenue: \nJust type 0 when you've finished inputting all values");
        revenue = scan.nextDouble();
        TotalRevenue += revenue;


    if(revenue==0) {

        break;
    }
}
    return TotalRevenue;
}
public static double getExpense() { 

    Scanner scan = new Scanner(System.in);

    while (true) {
        System.out.println("Enter your expenses: \nJust type 0 when you've finished inputting all values");
        expenses = scan.nextDouble();
        TotalExpenses += expenses;

    if(expenses==0) {

        break;

        }
    }
    return TotalExpenses;
}
}

第二个自定义类：

public class Business {

public static double ExpenseInput;
public static double RevenueInput;

public void REVENUE() {

    BusinessProject TOTAL = new BusinessProject();

    double RevenueInput = BusinessProject.TotalRevenue;

}

public static void EXPENSE() {

    BusinessProject TOTAL2 = new BusinessProject();

    double ExpenseInput = BusinessProject.TotalExpenses;
}

public void Profit() {

    double difference = (RevenueInput - ExpenseInput);

    if (difference <=1000) {

        System.out.println("Net Profit: " + (difference - (difference * 0.00175)));
    }

}

}

Answer 1

你得到0.0因为你没有调用你的方法来设置RevenueInput和ExpenseInput。

所以在你的情况下，在profit（）解决之前调用EXPENSE（）和REVENUE（）。

但是，我建议你查看你的程序结构和命名约定。您可以将变量作为函数的参数传递，例如：Profit(double expense, double revenue)，或者您可以在Business的构造函数中将其作为：public Business(double expense, double revenue)

你现在拥有的是一个循环依赖，你依赖于你的对象（Business）所使用的类（BusinessProject）中的静态变量。

我个人会像这样重构它：

public class Business {
    public static void profit(final double revenue, final double expense) {
        double difference = (revenue - expense);

        if (difference <=1000) {

            System.out.println("Net Profit: " + (difference - (difference * 0.00175)));
        }

然后，从您的主项目中，您只需拨打Business.profit(TotalRevenue, TotalExpense);

即可

Answer 2

而不是传递Business对象，而是在主类中创建新的Business对象。因此，属性将使用默认值

进行初始化

您必须从主类调用EXPENSE()和Profit()，并且必须将Business类作为参数传递给这些方法

Answer 3

public void Profit(BusinessProject bp) {

    double difference = (bp.TotalRevenue - bp.TotalExpenses);

    if (difference <=1000) {

        System.out.println("Net Profit: " + (difference - (difference * 0.00175)));
    }

}

并将其命名为

calc.Profit(this);

为什么我的程序返回“0.0”？

3 个答案: