如何在Java表达式中编写复利公式？

Question

到目前为止，我有

double futurevalue = moneyin * (1+ interest) * year;

Answer 1

The Java is correct, the fomular plain wrong. Compund interest is calculated this way:

K _n = K ₀ * (1 + p/100) ⁿ

where n is the number of periods and p is the "interest" per period (annual, if you look at years, p=annual/12 and n=12 if you look at month, have an annual interest as input and want to calculate for a year)

---

public double compoundInterest(double start, double interest, int periods) {
   return start * Math.pow(1 + interest/100, periods);
}

(Note: interest is a percentage value, like 4.2 for 4.2%)

Answer 2

I assume it's the power part of the formula you are having trouble with (multiplying by the year isn't right). For simple compound interest with whole numbers of years you can use the Math.pow() function that's part of the Java SDK.

double futureValue = moneyIn * Math.pow(1 + interest, year)