复利计算器

Question

我的目标是创建一个程序，向用户询问金额，询问每年、每月或每天的利率，询问如何复合，然后询问月、日或年的期限。

然后它会打印未来的价值以及获得的总利息。这是我到目前为止所拥有的，数字是不正确的。如果有人能帮助修改它并使其工作，我会非常感激。

import java.util.Scanner;

public class Compunding {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        double compoundingTerms;
        double period = 0;

        System.out.println("Enter an amount of money: ");
        double amount = sc.nextDouble();
        System.out.println("Enter an rate of Interest: ");
        double rate = sc.nextDouble();
        System.out.println("Enter per years, months, or days: ");
        String time = sc.next();
        System.out.println("Enter how it will be componded monthly, semi-anually, quarterlly, anually: ");
        String compoundRate = sc.next();
        System.out.println("Enter the term amount: ");
        double term = sc.nextDouble();
        System.out.println("Enter the term type (Monthy,Yearly,Daily}: ");
        String termType = sc.next();

        if (time.equals("years")) {
            period = 1;
        }
        if (time.equals("months")) {
            period = 12;
        }
        if (time.equals("days")) {
            period = 365;
        }

        if (compoundRate.equals("monthly")) {
            rate = (rate / 100) / 12;
            term = term * 12;
        }
        if (compoundRate.equals("semi-anually")) {
            rate = (rate / 100) / 2;
            term = term * 2;
        }
        if (compoundRate.equals("quarterlly")) {
            rate = (rate / 100) / 4;
            term = term * 4;
        }
        if (compoundRate.equals("anually")) {
            rate = rate / 100;
            term = term * 1;
        }

        double compoundPayment = 0;

        for (int i = 1; i <= term; i++ ) {
            if (i % period == 0 ) {
                colInterest(amount, rate);
            }
            compoundPayment = amount * (1.0 + rate);
        }

        System.out.println("The Final payment will be: " + compoundPayment);
    }

    public static double colInterest(double valueAmount, double valueInterest) {
        return valueAmount * valueInterest;
    }
}

Answer 1

因此，最初的计算和发布的内容存在一些问题。compoundPayment设置在for循环之外，并且只设置了一次，因此不会发生复合。此外，还请求了术语类型，但未使用，因此每个术语都假定为年。我认为很难遵循mod的for循环逻辑（我明白了，当我们到达一个复合的日子时，我们会给出利息），但要跟踪不同的单位是很困难的（所以我去了很多年，但可以用几天和像你这样的循环来证明）。我做了简化，假设给出的利率是年利率，但你可以每天乘以365，或者每月乘以12，或者，确保你的周期和天数有相同的单位。

同样的情况是，选择双精度而不是BigDecimal来表示金钱是我跟随你的领导并回答所问问题的。我并不是在争辩我在这里回答的是最好的方法（人们可以通过使用货币而不是假设它是美元来增强）。

一种不同的方法是使用指数来处理重复乘法，或者，即使没有，也可以简化for循环（这允许您在执行过程中打印报表，并允许货币四舍五入）。

我并不是在修复潜在的增强功能，比如一年中并不总是有365天，或者很好地格式化小数，或者更积极地检查输入。我试图给出一种可能的方法。

其中一个微妙之处是numPeriods的转换为（int），假设其他部分有效（我测试了364天的年复利没有利息，但365天有利息），确保未完成的期间不提供部分利息。

我希望这能有所帮助。

import java.util.Scanner;

public class Compounding {
private Scanner sc;

Compounding() {
    sc = new Scanner(System.in);
}


public double getAmount() {
    //enhancement: catch number format exceptions, negative numbers, etcetera, and presumbaly use a loop to retry
    System.out.println("Enter an amount of money: ");
    return sc.nextDouble();
}

//return interest as a rate
public double getInterestRate() {
    //enhancement, validate input, catch errors
    System.out.println("Enter an annual percent rate of interest: ");
    double rate = sc.nextDouble();
    return rate / 100;
}

public int getTimesCompoundedPerYear() {
    System.out.println("Enter how it will be componded monthly, semi-anually, quarterly, anually: ");
    String compoundRate = sc.next();
    if (compoundRate.equals("monthly")) {
        return 12;
    } else if (compoundRate.equals("semi-anually")) {
        return 2;
    } else if (compoundRate.equals("quarterly")) {
        return 4;
    } else if (compoundRate.equals("annually")) {
        return 1;
    } else {
        System.out.println("Unrecognized compounding, defaulting to monthly");
        return 12;
    }
}



//return term amount, units still tbd
//allowing for decimals in case someone says 6.5 years for dsomey=thing compounded more than once a year
public double getTermAmount() {
    //enhancement, validate input, catch errors
    System.out.println("Enter term amount: ");
    return sc.nextDouble();
}

public String getTermUnits() {
    System.out.println("Enter the term type (years, months, days): ");
    String termType = sc.next();
    if (termType.equals("years") || termType.equals("months") || termType.equals("days")) {
        return termType;
    } else {
        System.out.println("Unrecognized time period, defaulting to years.");
        return "years";
    }
}


public static void main(String[] args) {
    Compounding compounding = new Compounding();
    double period = 12;
    double amount = compounding.getAmount();
    double annualRate = compounding.getInterestRate(); //interest rates are always quoted as annual, no need to vary that
    int timesCompoundedPerYear = compounding.getTimesCompoundedPerYear();
    double term = compounding.getTermAmount();
    String termUnits = compounding.getTermUnits();
    double ratePerPeriod = annualRate / timesCompoundedPerYear;
    double timeInYears = term;
    if (termUnits.equals("months")) {
        timeInYears /= 12;
    } else if (termUnits.equals("days")) {
        timeInYears /= 365;
    }
    int numPeriods = (int) timeInYears * timesCompoundedPerYear;



    double compoundPayment = amount * Math.pow(1 + ratePerPeriod, numPeriods);

    System.out.println("The Final payment will be: " + compoundPayment);
}
}