Question

我正在尝试为我的代码创建三个不同的类：FutureValueApp，Validator和FinancialCalculations。我遵循指示，但是，当我运行代码时，我不断收到以下错误，并且不知道如何修复它。

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Exception in thread "main" java.lang.UnsupportedOperationException: Not supported yet.
    at FutureValueApp.getDoubleWithinRange(FutureValueApp.java:64)
    at FutureValueApp.main(FutureValueApp.java:17)

Java Result: 1

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到目前为止，这是我的代码：

import java.util.*;
import java.text.*;

import java.util.Scanner;
public class FutureValueApp
{
    public static void main(String[] args)
    {
        System.out.println("Welcome to the Future Value Calculator\n");

        Scanner sc = new Scanner(System.in);
        String choice = "y";
        while (choice.equalsIgnoreCase("y"))
        {
        // get the input from the user
            System.out.println("DATA ENTRY");
            double monthlyInvestment = getDoubleWithinRange(sc,
                "Enter monthly investment: ", 0, 1000);
            double interestRate = getDoubleWithinRange(sc,
                "Enter yearly interest rate: ", 0, 30);
            int years = getIntWithinRange(sc,
                "Enter number of years: ", 0, 100);

        // calculate the future value
            double monthlyInterestRate = interestRate/12/100;
            int months = years * 12;
            double futureValue = calculateFutureValue(
                monthlyInvestment, monthlyInterestRate, months);

        // get the currency and percent formatters
            NumberFormat currency = NumberFormat.getCurrencyInstance();
            NumberFormat percent = NumberFormat.getPercentInstance();
            percent.setMinimumFractionDigits(1);

        // format the result as a single string
            String results =
            "Monthly investment:\t"
            + currency.format(monthlyInvestment) + "\n"
            + "Yearly interest rate:\t"
            + percent.format(interestRate/100) + "\n"
            + "Number of years:\t"
            +  years + "\n"
            + "Future value:\t\t"
            + currency.format(futureValue) + "\n";

        // print the results
            System.out.println();
            System.out.println("FORMATTED RESULTS");
            System.out.println(results);

        // see if the user wants to continue
            System.out.print("Continue? (y/n): ");
            choice = sc.next();
            sc.nextLine();  // discard any other data entered on the line
            System.out.println();
        }
    }

    private static int getIntWithinRange(Scanner sc, String enter_number_of_years_, int i, int i0) {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    private static double getDoubleWithinRange(Scanner sc, String enter_monthly_investment_, int i, int i0) {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    private static double calculateFutureValue(double monthlyInvestment, double monthlyInterestRate, int months) {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
}

验证员类

import java.util.Scanner;

public class Validator 
{
    public static double getDouble(Scanner sc, String prompt)
    {
        double d = 0.0;
        boolean isValid = false;
        while (isValid == false)
        {
            System.out.print(prompt);
            if (sc.hasNextDouble())
            {
                d = sc.nextDouble();
                isValid = true;
            }
            else
            {
                System.out.println("Error! Invalid decimal value. Try again.");
            }
            sc.nextLine();  // discard any other data entered on the line
        }
        return d;
    } 

    public static double getDoubleWithinRange(Scanner sc, String prompt,
        double min, double max)
    {
        double d = 0.0;
        boolean isValid = false;
        while (isValid == false)
        {
            d = getDouble(sc, prompt);
            if (d <= min)
                System.out.println(
                    "Error! Number must be greater than " + min + ".");
            else if (d >= max)
                System.out.println(
                    "Error! Number must be less than " + max + ".");
            else
                isValid = true;
        }
        return d;
    }

    public static int getInt(Scanner sc, String prompt)
    {
        int i = 0;
        boolean isValid = false;
        while (isValid == false)
        {
            System.out.print(prompt);
            if (sc.hasNextInt())
            {
                i = sc.nextInt();
                isValid = true;
            }
            else
            {
                System.out.println("Error! Invalid integer value. Try again.");
            }
            sc.nextLine();  // discard any other data entered on the line
        }
        return i;
    }

    public static int getIntWithinRange(Scanner sc, String prompt,
        int min, int max)
    {
        int i = 0;
        boolean isValid = false;
        while (isValid == false)
        {
            i = getInt(sc, prompt);
            if (i <= min)
                System.out.println(
                    "Error! Number must be greater than " + min + ".");
            else if (i >= max)
                System.out.println(
                    "Error! Number must be less than " + max + ".");
            else
                isValid = true;
        }
        return i;
    }  
}

FinancialCalculations类

public class FinancialCalculations 
{

    public static double calculateFutureValue(double monthlyInvestment,
        double monthlyInterestRate, int months)
    {
        double futureValue = 0;
        for (int i = 1; i <= months; i++)
        {
            futureValue =
            (futureValue + monthlyInvestment) *
            (1 + monthlyInterestRate);
        }
        return futureValue;
    }  
}

我知道＆＃34; Private UnsupportedOperationException＆＃34;不应该被包括在内以使代码正常工作并且我需要公开它，但这太令人困惑了。

Answer 1

您缺少方法的实施

private static double getDoubleWithinRange(Scanner sc, String enter_monthly_investment_, int i, int i0) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

实施它，你就没事了

Answer 2

您有两个方法getDoubleWithinRange（同样适用于getIntWithinRange和calculateFutureValue）。您的问题是您拨错了。

这一行：

double monthlyInvestment = getDoubleWithinRange(sc,
                "Enter monthly investment: ", 0, 1000);

正在调用static类的getDoubleWithinRange FutureValueApp方法，该方法只能抛出UnsupportedOperationException。这样做是因为您没有使用拥有类限定方法调用。

您要调用的方法是Validator类中的方法，您需要像这样调用：

double monthlyInvestment = Validator.getDoubleWithinRange(sc,
                "Enter monthly investment: ", 0, 1000);

同样，行：

int years = getIntWithinRange(sc, "Enter number of years: ", 0, 100);

需要：

int years = Validator.getIntWithinRange(sc, "Enter number of years: ", 0, 100);

和

double futureValue = calculateFutureValue(
                monthlyInvestment, monthlyInterestRate, months);

需要成为：

double futureValue = FinancialCalculations.calculateFutureValue(
                monthlyInvestment, monthlyInterestRate, months);

每当你处理static方法时，始终使用拥有的类限定调用是一个好习惯 - 如果你在这种情况下这样做了，你就可以发现问题立刻就出现了。

从FutureValueApp删除冗余方法也是一个好主意。

Answer 3

如上所述，您尚未实现三种方法，它们会自动抛出异常。

private static int getIntWithinRange(Scanner sc, String enter_number_of_years_, int i, int i0) {
    return 0;
}

private static double getDoubleWithinRange(Scanner sc, String enter_monthly_investment_, int i, int i0) {
    return 0;
}

private static double calculateFutureValue(double monthlyInvestment, double monthlyInterestRate, int months) {
    return 0;
}

为了测试你的代码，你可以做我上面做的，只设置一个返回值，你的控制台应该打印出来：

欢迎使用未来价值计算器

数据输入

格式化结果每月投资：NOK 0.00每年利息   费率：0。0％年数：0未来价值：NOK 0.00

继续？（Y / N）：

java不支持的操作异常

3 个答案: