我正在使用Java教科书编写一个编程项目：
L＆amp; L银行最多可以处理30个拥有储蓄账户的客户。设计并实施管理帐户的程序。跟踪关键信息，让每个客户进行存款和取款。为无效事务生成错误消息。提示：您可能希望将帐户建立在第4章的Account类上。还提供了一种方法，可以在调用方法时为所有帐户添加3％的利息。
我不确定问题的具体要求，但我的猜测是允许并允许用户添加帐户，存款，取款，增加兴趣，获得余额，并将管理的帐户打印到阵列中。我不完全确定我必须制作一个数组，但整个章节都在数组上。
我的问题是我不确定如何启用用户创建帐户
（EX：Account acct1 = new Account ("Ted Murphy", 72354, 102.56);），
存钱（EX：acct1.deposit (25.85);），
取钱（EX：acct3.withdraw (800.00, 0.0);），
添加兴趣（EX：acct1.addInterest();），
或为所有帐户打印数组。
以下是Java教科书中使用所有方法找到的Account类：
//********************************************************************
// Account.java Author: Lewis/Loftus/Cocking
//
// Represents a bank account with basic services such as deposit
// and withdraw.
//********************************************************************
import java.text.NumberFormat;
public class Accounts
{
private NumberFormat fmt = NumberFormat.getCurrencyInstance();
private final double RATE = 0.035; // interest rate of 3.5%
private int acctNumber;
private double balance;
private String name;
//-----------------------------------------------------------------
// Sets up the account by defining its owner, account number,
// and initial balance.
//-----------------------------------------------------------------
public Accounts (String owner, int account, double initial)
{
name = owner;
acctNumber = account;
balance = initial;
}
//-----------------------------------------------------------------
// Validates the transaction, then deposits the specified amount
// into the account. Returns the new balance.
//-----------------------------------------------------------------
public double deposit (double amount)
{
if (amount < 0) // deposit value is negative
{
System.out.println ();
System.out.println ("Error: Deposit amount is invalid.");
System.out.println (acctNumber + " " + fmt.format(amount));
}
else
balance = balance + amount;
return balance;
}
//-----------------------------------------------------------------
// Validates the transaction, then withdraws the specified amount
// from the account. Returns the new balance.
//-----------------------------------------------------------------
public double withdraw (double amount, double fee)
{
amount += fee;
if (amount < 0) // withdraw value is negative
{
System.out.println ();
System.out.println ("Error: Withdraw amount is invalid.");
System.out.println ("Account: " + acctNumber);
System.out.println ("Requested: " + fmt.format(amount));
}
else
if (amount > balance) // withdraw value exceeds balance
{
System.out.println ();
System.out.println ("Error: Insufficient funds.");
System.out.println ("Account: " + acctNumber);
System.out.println ("Requested: " + fmt.format(amount));
System.out.println ("Available: " + fmt.format(balance));
}
else
balance = balance - amount;
return balance;
}
//-----------------------------------------------------------------
// Adds interest to the account and returns the new balance.
//-----------------------------------------------------------------
public double addInterest ()
{
balance += (balance * RATE);
return balance;
}
public double addInterestAll ()// I made this method myself but I am not sure if it is correct
{
balance += (balance * 0.03);
return balance;
}
//-----------------------------------------------------------------
// Returns the current balance of the account.
//-----------------------------------------------------------------
public double getBalance ()
{
return balance;
}
//-----------------------------------------------------------------
// Returns the account number.
//-----------------------------------------------------------------
public int getAccountNumber ()
{
return acctNumber;
}
//-----------------------------------------------------------------
// Returns a one-line description of the account as a string.
//-----------------------------------------------------------------
public String toString ()
{
return (acctNumber + "\t" + name + "\t" + fmt.format(balance));
}
}
这是正在建设的主要方法，我不确定我是否走在正确的轨道上：
import java.util.Scanner;
public class SixSix
{
public static void main (String[] args)
{
Scanner scan = new Scanner(System.in);
System.out.println("Input (0) to add account, (1) to deposit,");
System.out.println("(2) to withdraw, (3) to add interest, (4) to add interest to all");
System.out.println("(5) to get balance, (6) to get account number, (7) to print");
int input = scan.nextInt();
while (input == 0){
System.out.println("To create an account, please enter your name");
String name = scan.nextLine();
System.out.println("Please enter your account number");
int accNum = scan.nextInt();
System.out.println("Please Enter account balance");
double accBalance = scan.nextDouble();
//System.out.format
}
while (input == 1)
{
System.out.println("To deposit money to an account");
}
while (input == 2)
{
System.out.println("To withdraw money from an account");
}
while (input == 3)
{
System.out.println("To add Interest");
}
while (input == 4)
{
System.out.println("To add Interest to all");
}
while (input == 5)
{
System.out.println("To get balance");
}
while (input == 6)
{
System.out.println("To get account number");
}
while (input == 7)
{
System.out.println("Printing account");
}
}
}
答案 0 :(得分：1)
在我看来，你似乎正走在正确的轨道上。我推断问题（在书中）的措辞和你发布的代码尚未存在的代码，在这种情况下你需要允许系统的用户创建它们。然后，在更改帐户时，用户首先必须提供帐号，以便您可以识别正确的Accounts对象。
我猜测由于这一章是关于数组的，所以它可能还没有涵盖地图（否则这将是一种将帐号与Accounts个对象相关联的便捷方式）。如果你使用数组，那么账号从0到29似乎是一个好主意。
以下是一个如何实现AccountsManager类的示例，该类可帮助您从一组帐户中添加和检索帐户。
public class AccountsManager {
private Accounts[] accounts;
private final int capacity;
private int current;
public AccountsManager(int capacity) {
this.capacity = capacity;
accounts = new Accounts[capacity];
current = 0;
}
// returns the account number of the new account
// or -1 if no account could be made
public int addAccount(String name) {
if (current >= capacity) {
return -1;
}
accounts[current] = new Accounts(name, current, 0);
return current++;
}
public Accounts getAccount(int number) {
if (number >= current || number < 0) {
return null;
}
return accounts[number];
}
}
在上面，capacity属性只是数组的大小，这是可以创建的Accounts个对象的最大数量（根据练习，这应该是30）。 current属性（随意重命名为更具信息性的内容！）跟踪数组中应创建下一个Accounts对象的位置。每次添加帐户时，这一增长为1。
在您的代码中，您现在可以执行以下操作：
AccountsManager manager = new AccountsManager(30);
// ...
if (input == 0) {
// Create new account
System.out.println("To create an account, please enter your name");
String name = scan.nextLine();
int accountNumber = manager.addAccount(name);
if (accountNumber == -1)
System.out.println("The bank can't handle any more accounts.");
else
System.out.println("Your account number is "+accountNumber);
} else if (input == 1) {
// Deposit money to account
System.out.println("What is your account number?");
int accountNumber = scan.nextInt();
// Check if account exists
if (manager.getAccount(accountNumber) == null) {
System.out.println("That account doesn't exist!");
} else {
System.out.println("How much do you want to deposit?");
double amount = scan.nextDouble();
manager.getAccount(accountNumber).deposit(amount);
}
}
也许最好在AccountsManager类中创建新方法以进行存款等，但这至少表明了一般结构可能是什么样的。