Question

我已经在这个项目上工作了大约一个星期，而我似乎无法正确地计算数学。它的输出值，而不是正确的值。我已经多次查看过我的价值观了数数。我绝望了!!我的程序计算了多年来长度的年度利益贷款是。其次，它计算每年原始贷款需要支付多少钱贷款总长度。

import java.util.Scanner;


public class mortgageCalc {


     public static void main(String[] args)
      {
        // Other declarations for main program go here
        Scanner keyboard = new Scanner(System.in);
        double annualInterest;
        int loanLength;
        double loanAmount;


        // Step 1: prompt for, read in, and store the input values.
        System.out.print("Enter loan amount: ");
        loanAmount = keyboard.nextDouble();
        System.out.print("Enter length of the loan: ");
        loanLength = keyboard.nextInt();
        System.out.print("Enter interest rate as percent: ");
        annualInterest = keyboard.nextDouble();

        double newMonthlyPayment = payment(annualInterest,loanLength,loanAmount);
        double totalInterest = (newMonthlyPayment * loanLength*12)-loanAmount;
        printTotals(newMonthlyPayment, totalInterest,annualInterest,loanLength,loanAmount);
        double balance = loanAmount;
        double monthlyInterestRate = annualInterest/1200;

        for (int year = 1; year <= loanLength; year++)
        {
          double remainingMonthlyInterest = getMonthlyInterest (balance, monthlyInterestRate);
          double remainingInterest = totalInterest + remainingMonthlyInterest;
          balance = getRemainingBalance(balance, newMonthlyPayment, remainingMonthlyInterest);
          System.out.println("Monthly interest:"+remainingMonthlyInterest);
          System.out.println("new balance:"+balance);
        }
      } // end of main

      public static double payment(double annualInterest, int loanLength, double loanAmount)
      {
        double i = (annualInterest/1200);
        double n = (loanLength*12);
        double e1 = i+1;
        double e2 = Math.pow(e1,n);
        double e3 = e2-1;
        double e4 = i * e2;
        double e5 = e2-1;
        double monthlyPayment = loanAmount*(e4/e5);
        return monthlyPayment;
      } // end of function payment
      public static void printTotals(double newMonthlyPayment, double totalInterest,double
      annualInterest,int loanLength, double loanAmount)
      { 
           System.out.print("For a "+loanLength);
           System.out.printf(" year loan of $%5.2f ",loanAmount);
           System.out.printf("at %5.2f ",annualInterest);
           System.out.println("interest--");

           System.out.printf("Monthly payment: $ %5.2f\n",newMonthlyPayment);
           System.out.printf("Total interest:  $ %6.2f\n",totalInterest);
       } // end of function printTotals
      public static double getMonthlyInterest (double balance, double monthlyInterestRate)
      {
          double monthlyInterest=0.0;
          for(int month=1; month<=12; month++)
          {
           monthlyInterest = balance * monthlyInterestRate;
          }
          return monthlyInterest;
      }
      public static double getRemainingBalance (double balance, double newMonthlyPayment,
      double monthlyInterest)
      {
         double newBalance=0.0;
         for(int month=1; month<=12; month++)
        {
          newBalance = balance-(newMonthlyPayment-monthlyInterest);
        }
       return newBalance;
      }
} // end of class MortgageCalc

Answer 1

您的getMonthlyInterest()方法似乎不正确。虽然我不确定数学应该是什么，但您目前所拥有的内容将迭代12次（每月一次）并且每次完全重置monthlyInterest为balance*monthlyInterestRate

你应该没有for循环，或者更准确地说应该每月将monthlyInterest添加到自己：

monthlyInterest = monthlyInterest + balance*monthlyInterestRate;

与您的getRemainingBalance()方法相同。它将在每月for循环的每次迭代中重置。要么摆脱for循环，要么确保你的逻辑是正确的 - newBalance使用的信息在循环过程中每个月都会发生变化。

贷款计算器数学不正确

1 个答案: