返回問題的方法

Question

我有一個方法返回到主要方法的問題。這就是說，「回報金額」中的金額不能解析爲變量。我在哪裏關閉？

這是我得到的消息：在該行 多個標記 - 太虛方法不能返回 值 - 量不能被解析爲 可變

下面是代碼：

import java.util.Scanner; 

public class Investment { 
    public static void main(String[]args) { 
     Scanner input = new Scanner(System.in); 

     System.out.print("Enter the amount invested: "); 
     double amount = input.nextDouble(); 

     System.out.print("Enter the annual interest rate: "); 
     double interest = input.nextDouble(); 

     int years = 30; 

     System.out.print(futureInvestmentValue(amount, interest, years)); //Enter output for table 
    } 

    public static double futureInvestmentValue(double amount, double interest, int years) { 

     double monthlyInterest = interest/1200; 
     double temp; 
     double count = 1; 

     while (count < years) 
      temp = amount * (Math.pow(1 + monthlyInterest,years *12)); 
     amount = temp; 

     System.out.print((count + 1) + " " + temp); 
    } 

    { 
     return amount; 
    } 
} 

Answer 1

你的花括號不正確。編譯器和我對此感到困惑。

這應該工作（至少語法）：

import java.util.Scanner; 

public class Investment { 
    public static void main(String[] args) { 
     Scanner input = new Scanner(System.in); 

     System.out.print("Enter the amount invested: "); 
     double amount = input.nextDouble(); 

     System.out.print("Enter the annual interest rate: "); 
     double interest = input.nextDouble(); 

     int years = 30; 

     System.out.print(futureInvestmentValue(amount, interest, years)); 
    } 

    public static double futureInvestmentValue(
      double amount, double interest, int years) { 

     double monthlyInterest = interest/1200; 
     double temp = 0; 
     double count = 1; 

     while (count < years) 
      temp = amount * (Math.pow(1 + monthlyInterest, years * 12)); 
     amount = temp; 

     System.out.print((count + 1) + " " + temp); 

     return amount; 
    } 
} 

Answer 2

從它自己的範圍作爲一個開始刪除amount。同樣從方法futureInvestmentValue中，您將amount作爲參數，但該值永遠不會被修改，因此您將返回傳遞的相同值，這很可能不是所需的結果。

Answer 3

1. 從它自己的範圍內刪除return amount
2. 方法futureInvestmentValue ...你不能修改任何參數的方法裏面，所以你必須申報金額之外的另一個變量的方法內（也許這是temp變量，你繼續使用），並返回，而不是

3. 當你返回的東西，返回語句總是在方法內。決不外面，而裏面自己的括號（從來沒見過這個...）

   import java.util.Scanner; 
   
   public class Investment { 
       public static void main(String[]args) { 
        Scanner input = new Scanner(System.in); 
   
        System.out.print("Enter the amount invested: "); 
        double amount = input.nextDouble(); 
   
        System.out.print("Enter the annual interest rate: "); 
        double interest = input.nextDouble(); 
   
        int years = 30; 
   
        System.out.print(futureInvestmentValue(amount, interest, years)); //Enter output for table 
       } 
   
       public static double futureInvestmentValue(double amount, double interest, int years) { 
   
        double monthlyInterest = interest/1200; 
        double temp; 
        double count = 1; 
   
        while (count < years) { 
         temp = amount * (Math.pow(1 + monthlyInterest,years *12)); 
         System.out.print((count + 1) + " " + temp); 
        } 
   
        return amount; 
       } 
   }