java - 简单的 Java 现值计算器不工作

Question

我以前没有使用过 java，我很困惑为什么我写的一个简单的现值计算器不起作用。由于某种原因，现值公式返回一个超小数字？看看你是否能发现我的错误:

// Import all utilities
import java.text.DecimalFormat;
import java.util.*;

// Base class
public class Project2
{

   // Main function
   public static void main(String[] args)
   {
      // Define variables
      double p = 0.0;
      double f = 0.0;
      double r = 0.0;
      double n = 0.0;
      String another = "Y";

      // Create a currency format
      DecimalFormat dollar = new DecimalFormat("#,###.00");

      // Create a new instance of the scanner class
      Scanner keyboard = new Scanner(System.in);

      // Loop while another equals "Y"
      while(another.equals("Y"))
      {
         // Get future value
         System.out.println("Future value: ");
         f = Double.parseDouble(keyboard.nextLine());

         // Get annual interest rate
         System.out.println("Annual interest rate: ");
         r = Double.parseDouble(keyboard.nextLine());

         // Get Number of years
         System.out.println("Number of years: ");
         n = Double.parseDouble(keyboard.nextLine());

         // Run method to find present value and display result
         p = presentValue(f, r, n);
         System.out.println("Present value: $" + p );

         // Ask if user wants to enter another
         System.out.println("Enter another?(Y/N) ");
         another = keyboard.nextLine().toUpperCase();
      }

   }

   public static double presentValue(double f, double r, double n)
   {
      // Do math and return result
      double p = f / Math.pow((1 + r), n);
      return p;
   }
}

Answer 1

假设您将 R 输入为 % per annum 即例如R = 4.3%，您可能希望将函数修改为:

double p = f / (Math.pow((1 + (r/100.0)), n));
return p;

如果这不是您想要的，您可能需要将 R=4.3% p.a 的值输入为

4.3/100 = 0.043 而不是 4.3。