Question

我有糟糕的编码习惯，我从糟糕的代码中汲取，但是我正努力尝试解决这些问题。我的主要问题是尝试通过构造函数传递初始参数，我还没有用Java编写一年的代码，所以让我知道一切都是错的！

public class AccountHolder {

     public static void main(String args[])
     {
        //Introduce scanner
           Scanner sc = new Scanner(System.in); //Used to take input from user
           System.out.println("Welcome to the bank program! Can you tell me your current balance?");

       input = sc.nextDouble();
       AccountHolder(input);
      }

        // Introduce private field members
        private static double annualInterestRate; //Constant to hold annual interest rate
        private static double fee; // Constant to hold the withdrawal fee
        private double balance; // variable to hold the balance
        private double rateUpdate; // variable to hold the value to update the rate
        private static double input; // variable to hold user input
        private double test; // variable to test whether or not user will drop below $100.

        // introduce a DecimalFormat object
        DecimalFormat twoPlace = new DecimalFormat("0.00"); // Used to keep values to 2 significant figures.

        // Introduce public methods

        public AccountHolder(double input) 
        {   
            balance = input;
        }

        public void deposit(double input)
        { 
            balance = balance + input;
            System.out.println("Your new balance is: $" + twoPlace.format(balance));
        }

        public void withdrawl(double input)
        {
            test = balance;
            balance = balance - input;

            if (balance < 100.0)
            {
                balance = balance + input;
                System.out.println("Your balance is not allowed to drop below $100.00. Please try again when you have more funds.");
            }

            if (test >= 500 && balance < 500)
            {
                balance = balance - fee;
                System.out.println("You have been charged an additional $50 for dropping below $500.00.");
            }

            System.out.println("Your new balance is: $" + twoPlace.format(balance));
        }



        public void monthlyInterest()
        {
            balance += balance * (annualInterestRate / 12.0);
        }

        public static void modifyMonthlyInterest(double rateUpdate)
        {
            annualInterestRate = rateUpdate;
            while (annualInterestRate <= 0 || annualInterestRate >= 1.0)
            {
                System.out.println("Error! Interest rates must be between 0 and 1. We need to keep our money!");
                annualInterestRate = sc.nextDouble();
            }

        }

        public String toString()
        {
            return String.format("$%.2f", balance);

        }



}

Answer 1

而不是

AccountHolder(input);

你需要做

new AccountHolder(input);

当你缺少＆＃34; new＆＃34;时，它被解释为方法调用。使用＆＃34; new＆＃34;它被解释为对构造函数的调用。

PS：我想建议你研究一下变量的范围。例如。你可以定义＆＃34;输入＆＃34; ＆＃34; main＆＃34;内部的变量方法而不是静态类变量。这提高了代码的可读性。

Answer 2

这是你的构造函数：

ControlTemplate

你传递的参数如下：

public AccountHolder(double input) {   
        balance = input;
 }

您缺少使用关键字 new 来实际创建该类的新实例...

喜欢

AccountHolder(input);

将参数传递给构造函数

2 个答案: