Question

您好我正在尝试编写一个使用固定费率计算未来投资价值的程序，而我的变量存在问题。任何帮助都会非常感谢你提前谢谢！

  /**
  * NAME:
  * DATE: November 3, 2015
  * FILE: 
  * COMMENTS: This program caculates a future investment value using a fixed rate
  */
  import java.util.Scanner;

public class lab12
{
   public static void main(String[] args)
   {
   //declare variables
   double yearlyInterstRate;
   double monthlyInterestRate;
   double monthlyInvestmentAmount;
   double years;
   double months;

   //Create Scanner Object
   Scanner keyboard= new Scanner(System.in);

   //Get Investment Information
   System.out.print("Hello we will be caculating the future of your fixed monthly investment, I will need to collect some information from you.");
   System.out.print("What is your monthly investment amount?");
   monthlyInvestmentRate=keyboard.nextLine();
   System.out.print("How many years wil you be investing for?");
   years=keyboard.nextLine();
   System.out.print("What is your yearly interest rate?");
   yearlyInterestRate=keyboard.nextLine();
   //Caculate the future rate
   {
      months=years*12;
      monthlyInterestRate=yearlyInterestRate/12/100;
      futureValue= CaculateFuturevalue(monthlyInvestedAmount,monthlyInterestRate,months);
      System.out.print("Your future value is $"+futureValue);
    }
 } //Close Main
} //close lab12

Answer 1

你在变量中拼写错误。

您已宣布yearlyInterstRate，但您正在使用yearlyInterestRate，因此您需要使用声明的变量。

您也需要使用monthlyInvestmentAmount而不是monthlyInterestRate。

Answer 2

此代码将执行：

public class lab12
{
    public static void main(String[] args)
    {
        //declare variables
        double yearlyInterstRate;
        double monthlyInterestRate;
        double monthlyInvestmentAmount=0; // you forgot to initialize this value
        double years;
        double months;
        double futureValue;
        //Create Scanner Object
        Scanner keyboard= new Scanner(System.in);

        //Get Investment Information
        System.out.print("Hello we will be caculating the future of your fixed monthly investment, I will need to collect some information from you.");
        System.out.print("What is your monthly investment amount?");
        monthlyInterestRate=keyboard.nextDouble();
        System.out.print("How many years wil you be investing for?");
        years=keyboard.nextDouble();
        System.out.print("What is your yearly interest rate?");
        yearlyInterstRate=keyboard.nextDouble();
        //Caculate the future rate

            months=years*12;
            monthlyInterestRate=yearlyInterstRate/12/100;
            futureValue= caculateFuturevalue(monthlyInvestmentAmount,monthlyInterestRate,months);
            System.out.print("Your future value is $"+futureValue);

    } 
}

现在做了一些改进：

使用nextDouble()代替nextLine()，因为你的变量是双倍的，而不是String。
从upperCase为您的班级命名，因此Lab12而不是lab12
争论验证会很好（检查给定值是否大于零）

Cannont找不到符号错误，不兼容的类型

2 个答案: