财务Java编译器告诉我，我并没有启动变量“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、十进制形式的利率值和每月付款值。有了这些信息，我想输出美元利息金额、本金金额和新余额。这是我的密码：

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

您不应该声明从标准输入读取3个扫描仪。声明一个，然后继续阅读。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，扫描仪是从输入流读取的对象，而不是正在读取的值。您不需要为每个要读取的值安装新的扫描仪

Answer 2

正如@nhouser9所说，您不需要三个扫描器，而在回答您的问题时，编译器会说变量没有初始化，因为您只初始化了最后一个变量（balance）。java中的多次初始化不会像您预期的那样起作用（使用相同的值初始化所有变量）