Java编译器告诉我我还没有初始化变量 "interest"或 "pmt"

Question

我正在尝试编写一个摊销计算器，用户可以在其中输入余额值、小数形式的利率值以及每月付款值。有了这些信息，我想输出以美元计的利息金额、本金金额和新余额。这是我的代码:

import java.util.Scanner;
public class Amortization{
   public static void main(String []args){
      Scanner pmt, interest, balance = new Scanner(System.in);
      System.out.println("What is your balance?");
      double b = balance.nextDouble();
      System.out.println("What is your interest rate in decimal?");
      double i = interest.nextDouble();
      System.out.println("What is your monthly payment?");
      double p = pmt.nextDouble();
      double pv = p-(b*i);
      System.out.println("Your interest amount is " + (b*i));
      System.out.println("Your principal amount is " + pv);
      System.out.println("Your new balance is " + (b-pv));
   }
}

Answer 1

您不应声明 3 个扫描仪来读取标准输入。声明一个并继续阅读它。像这样:

import java.util.Scanner;
public class Amortization{
   public static void main(String []args){
      Scanner input = new Scanner(System.in);
      System.out.println("What is your balance?");
      double b = input.nextDouble();
      System.out.println("What is your interest rate in decimal?");
      double i = input.nextDouble();
      System.out.println("What is your monthly payment?");
      double p = input.nextDouble();
      double pv = p-(b*i);
      System.out.println("Your interest amount is " + (b*i));
      System.out.println("Your principal amount is " + pv);
      System.out.println("Your new balance is " + (b-pv));
   }
}

这里的要点是扫描器是从输入流中读取的对象，而不是正在读取的值。您不需要一个新的扫描仪来读取您想要读取的每个值。