java - 帐户类别错误 2

Question

我仍然无法弄清楚最有效的方法到底是如何做到这一点的。基本上，我试图为创建的 Account 数组中的每个对象设置 balance = 0。我尝试使用 for 循环并为每个创建的帐户设置 balance = 0，但我不确定如何进行这项工作，因为 balance 变量是在具有所有方法的类中创建的。我整天都在尝试解决这个问题，但没有运气。谢谢。

Main method:
import java.util.Scanner;
import java.text.NumberFormat;
public class Account2
{
  public static void main(String[] args)
  {
    Scanner scan = new Scanner(System.in);
    Account[] acct = new Account[30];
    for (int count2; count2 < 30; count2++)
    {
      balance = 0; //Initial balance is always set to zero to be able to run fresh program every time
    }
    System.out.println("Enter your account number (1-30): ");
    int key = scan.nextInt() - 1;
    int reset = 0;
    while (reset == 0)
    {
      System.out.println("Enter W for withdrawl; D for deposit; X to escape");
      char choice = scan.next().charAt(0);

      if  (choice == 'W' || choice == 'w' || choice == 'D' || choice == 'd' || choice == 'x' || choice == 'X')
      {
        if (choice == 'W' || choice == 'w')
        {
          System.out.println("Enter amount to withdraw: ");
          Double withdraw1 = scan.nextDouble();
          if (withdraw1 <= acct[key].getBalance())
          {
            acct[key].withdraw(withdraw1);
            System.out.println("User # " + key++ + " funds after withdraw: " + acct[key].getBalance() + "$");
            System.out.println("User # " + key++ + " funds after interest: " + acct[key].addInterest() + "$");
            reset++;
          }
          else
            System.out.println("Insufficient funds.");
        }

        if (choice == 'D' || choice == 'd')
        {
          System.out.println("Enter amount to deposit: ");
          Double deposit1 = scan.nextDouble();
          if (deposit1 > 0)
          {
            acct[key].deposit(deposit1);
            System.out.println("User # " + key++ + " funds after deposit: " + acct[key].getBalance() + "$");
            System.out.println("User # " + key++ + " funds after interest: " + acct[key].addInterest() + "$");
            reset++;
          }
          else
            System.out.println("Use the withdrawl feature to withdrawl money.");

        }
        if (choice == 'x' || choice == 'X')
          System.out.println("Thank You for using this bank.");
          reset++;
      }
      else
        {
          System.out.println("Invalid entry, please try again");
          reset = 0;
        }
    }
  }
}

支持类:

public class Account
{
  private final double RATE = 0.03; //Interest is 3%

  private int acctNumber;
  private String name;
  private balance;

  //Defines owner, account number, and initial balance.
  public Account(String owner, int account, double initial)
  {
    name = owner;
    acctNumber = account;
    balance = initial;
  }

  //deposits a specified amount and returns new balance
  public double deposit(double amount)
  {
    balance = balance + amount;
    return balance;
  }

  //withdraws the specified amount from the account and applies the fee
  //                                                  + returns balance
  public double withdraw(double amount)
  {
    int fee = 1;
    balance = balance - amount - fee;
    return balance;
  }

  //Adds interest to the account
  public double addInterest()
  {
    balance += (balance * RATE);
    return balance;
  }
  public double getBalance()
  {
    return balance;
  }

  //returns a one line description of the account as a string
  public String toString()
  {
    NumberFormat fmt = NumberFormat.getCurrencyInstance();
    return acctNumber + "/t" + name + "/t" + fmt.format(balance);
  }
}

Answer 1

在外部类中，您只能以其可见(例如公共(public))API 中公开的方式与 Account 进行交互。

在这种情况下，当前的方法是withdraw()当前的balance:

acct[i].withdraw(acct[i].getBalance());

尽管这种特定情况会使余额变为负数，因为您收取取款费用(这对调用类是隐藏的)。

如果您要在 Account 上公开一个 setBalance 方法，您可以改为这样做

acct[i].setBalance(0);

但是仔细观察，您遇到的问题似乎实际上是在初始化帐户数组。你可以这样做:

for (int count2; count2 < 30; count2++)
{
  acct[count2] = new Account(owner, count2, 0);
}