java - 3 个支票账户 2 个 build 者为客户提供没有 overdraw 的服务，但是不想 overdraw 的客户可以得到一个

Question

ChequeAccount 类扩展了 Account 类。帐户类包含 ID、名称和余额属性。 ChequesAccount 类具有来自帐户的 overdraftLimit、amtOverdrawn 和 transactionNo 以及 super(ID、姓名、余额)。我在数组中创建了 3 个 chqAccount 对象并打印了它们的详细信息。 Ringo 已选择退出其 chq 帐户中的 overdraw 功能，因此为他提供了单独的构造函数。然而，当我打印所有支票帐户的详细信息时，他是唯一获得 overdraw 便利的人。它让我头疼，请帮忙

public class TestAccounts6
{
   private static ChequeAccount[] chqAccount = new ChequeAccount[5];
   private static int indexNo = 0;

   public static void main(String[] args)
   {
      ChequeAccount c1 = new ChequeAccount("S1111", "Paul", 1245.00, 0, 0, 0);
      ChequeAccount c2 = new ChequeAccount("S2222", "Ringo", 2500.00);
      ChequeAccount c3 = new ChequeAccount("S3333", "John", 1575.00, 0, 0, 0);
      chqAccount[0] = c1;
      chqAccount[1] = c2;
      chqAccount[2] = c3;
      indexNo = 3;
      System.out.printf("%-10s%-10s%-10s%-10s%-10s%-10s%n", "ID", "Name", "Balance",
                        "Overdraft", "Amount", "No of");
      System.out.printf("%-10s%-10s%-10s%-10s%-10s%-10s%n", "", "", "",
                        "Limit", "Overdrawn", "Transactions\n");
      for (int i = 0; i < indexNo; i++)
      {
         chqAccount[i].print();
      }

   }

}
public class ChequeAccount extends Account
{
   protected double overdraftLimit = 10000;
   protected double amtOverdrawn = 0;
   protected int transactionNo = 0;

   // constructor
   public ChequeAccount(String ID, String name, double balance,
                        double overdraftLimit, double amtOverdrawn,
                        int transactionNo)
   {
      super(ID, name, balance);
      this.overdraftLimit = overdraftLimit;
      this.amtOverdrawn = amtOverdrawn;
      this.transactionNo = transactionNo;
   }

   public ChequeAccount(String ID, String name, double balance)
   {
      super(ID, name, balance);
   }

   public void print()
   {

      System.out.printf("%-10s%-10s$%-9.2f$%-9.2f$%-9.2f%-10d%n", ID, name,
                        balance, overdraftLimit, amtOverdrawn, transactionNo);
   }

}
public class Account
{
   protected String ID;
   protected String name;
   protected double balance;

   // Constructor
   public Account(String ID, String name, double balance)
   {
      this.ID = ID;
      this.name = name;
      this.balance = balance;
   }

预期林戈不会获得 overdraw 额度，而约翰和保罗会。与预期相反

Answer 1

它的行为正确。因为

1. 您已创建 3 个 chqAccount 对象

ChequeAccount c1 = new ChequeAccount("S1111", "Paul", 1245.00, 0, 0, 0);

ChequeAccount c2 = new ChequeAccount("S2222", "Ringo", 2500.00);

ChequeAccount c3 = new ChequeAccount("S3333", "John", 1575.00, 0, 0, 0);

当您尝试打印该对象的值时。它的打印方式如下。

ID Name Balance Overdraft Amount No of
Limit Overdrawn Transactions

S1111 Paul $1245.00 $0.00 $0.00 0 S2222
Ringo $2500.00 $10000.00 $0.00 0 S3333 John
$1575.00 $0.00 $0.00 0

当我们观察上述情况并检查林戈的详细信息时。它的余额为: $10000.00 因为您尚未为 Ringo 分配任何值。但在 ChequeAccount 中如下。

  protected double overdraftLimit = 10000;
  protected double amtOverdrawn = 0;
  protected int transactionNo = 0;

它有默认值。这样在打印时它就采用默认值。