使用Java在for循環之外返回值時遇到麻煩

Question

我在返回for語句之外的值時遇到麻煩。 在我下面的語法中，我必須在for循環之外聲明finalAmount變量，因為如果不這樣做，它將無法正常工作。 返回值為0，我不希望這樣。 如何在Java中的for循環語句之外使用變量？

謝謝

import java.util.Scanner;

public class CompundInterest2 {
    public static void main(String[] args){
        Scanner input = new Scanner(System.in);

        double amount, rate, year;

        System.out.println("What is the inital cost? Dude");
        amount = input.nextDouble();
        System.out.println("What is the interest rate?");
        rate = input.nextDouble();
        rate = rate/100;
        System.out.println("How many years?");
        year = input.nextDouble();

        input.close();


        justSayit(year, rate, amount);

    }

    private static double thefunction(double amount, double rate, double year){
        double finalAmount = 0;  // This is where I'm running into trouble. If I don't declare this variable the program won't work. But if I declare it, it works but returns 0.
        for(int x = 1; x < year; x++){
            finalAmount = amount * Math.pow(1.0 + rate, year); 
        }
        return finalAmount;
    }

    public static void justSayit(double year, double rate, double amount){
        double awesomeValue = thefunction(amount, year, rate);
        System.out.println("For " + year + " years an initial " + amount + 
                " cost compounded at a rate of " + rate + " will grow to " + awesomeValue); 
    }

Answer 1

我想您想添加所有這樣的金額-

for(int x = 1; x < year; x++){
  finalAmount += amount * Math.pow(1.0 + rate, year); // += 
}

此外，您的justSayit函數調用thefunction是不正確-

double awesomeValue = thefunction(amount, rate, year); /* not amount, year, rate */

Answer 2

問題是，當您調用該函數時，它具有錯誤順序的參數：

double awesomeValue = thefunction(amount, year, rate);

該方法在訂單金額，費率，年份中期望它們

Answer 3

for循環中代碼的麻煩在於它不依賴於循環變量x，因此很可能您忘記了某些內容，否則循環將無用。