Java中的复合兴趣程序

Question

我想在最后写一个do while while循环来编写这个复利兴趣程序，我无法弄清楚如何打印出最终的金额。

这里是我到目前为止的代码：

public static void main(String[] args) { 
    double amount; 
    double rate; 
    double year; 

    System.out.println("This program, with user input, computes interest.\n" + 
    "It allows for multiple computations.\n" + 
    "User will input initial cost, interest rate and number of years."); 

    Scanner keyboard = new Scanner(System.in); 

    System.out.println("What is the initial cost?"); 
    amount = keyboard.nextDouble(); 

    System.out.println("What is the interest rate?"); 
    rate = keyboard.nextDouble(); 
    rate = rate/100; 

    System.out.println("How many years?"); 
    year = keyboard.nextInt(); 


    for (int x = 1; x < year; x++){ 
     amount = amount * Math.pow(1.0 + rate, year); 
       } 
    System.out.println("For " + year + " years an initial " + amount + " cost compounded at a rate of " + rate + " will grow to " + amount); 


    String go = "n"; 
    do{ 
     System.out.println("Continue Y/N"); 
     go = keyboard.nextLine(); 
    }while (go.equals("Y") || go.equals("y")); 
} 

}

Answer 1

麻烦的是，amount = amount * Math.pow(1.0 + rate, year);。您将用计算的金额覆盖原始金额。您需要一个单独的值来保持计算的值，同时仍保持原始值。

所以：

double finalAmount = amount * Math.pow(1.0 + rate, year); 

在输出

然后：

System.out.println("For " + year + " years an initial " + amount + 
    " cost compounded at a rate of " + rate + " will grow to " + finalAmount); 

编辑：另外，您也可以节省一条线，一个变量，只是做了计算内联，因为这样的：

System.out.println("For " + year + " years an initial " + amount + 
    " cost compounded at a rate of " + rate + " will grow to " + 
    (amount * Math.pow(1.0 + rate, year)));