我如何计算在没有无限循环的情况下达到所需余额的年数？

Question

我目前正在为大学做软件基础教程，而我目前仍在解决这个问题。

“计算每年在银行帐户中获得指定金额的款项所需的年数，假设在每年年底支付利息，并且不提取任何款项。该程序应提示用户输入当前余额以磅为单位，所需的余额以磅为单位，利率以百分比表示。然后，它应计算并输出达到所需余额所需的年数，并在每年年底输出当前余额。”

到目前为止，我已经尝试过了，也尝试过移动变量，但是它始终会导致无限循环。如何停止呢？

package interest;

import java.util.Scanner;

public class Interest {

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);

        System.out.println("hello what is your current balance ?");

        double balance = input.nextDouble();

        System.out.println("What is your required Balance");

        Double requiredBal = input.nextDouble();

        System.out.println("what is your current interest rate in %");

        double interest = input.nextDouble();

        int years = 0;

        double totalbalance=0;

        do {

            double intbalance = (balance /100) * interest;

            totalbalance = balance + intbalance;

            years ++;

            System.out.println("your balance after " + years +" years = " + totalbalance);

        }while(totalbalance <= requiredBal);

        System.out.println("it will take" + years + " years to get to " + requiredBal);

    }

}

它应该是这样的

enter current balance

100

enter required balance

200

enter interest rate   

10

balance after 1 year = 110.0 

balance after 2 year = 120.0  

balance after 3 year = 130.0 

balance after 4 year = 140.0

balance after 5 year = 150.0 

balance after 6 year = 160.0 

balance after 7 year = 170.0

balance after 8 year = 180.0

balance after 9 year = 190.0 

balance after 10 year = 200.0

It will take 10 years to reach the required balance.

Answer 1

让我们做一些婴儿数学。指数增长被定义为y=a(1+r)^x其中a是初始值和r是的兴趣（0和1之间）。此功能可映射X年的银行帐户余额。我们想要逆。如果对这个方程求逆，则得到y=logx/(log[a(1+r)]。x如果您可以进行一点数学运算，它将告诉您多少年才达到不需要循环的平衡。