如何在Java中将资金从一个银行帐户转移到另一个银行帐户？

任务： 更改帐户类别，以便资金可以从一个帐户转移到另一个帐户。可以把这看作是从一个账户取钱并存入另一个账户。更改Banking类的主要方法以显示此新服务

我正在开发一个银行账户类，可以从银行账户余额中存款和取款。我正在处理作业的类部分，在那个部分中，您将为驱动程序声明所有方法。我的任务要求我制定一种方法，从一个账户中提取资金，然后将这些资金存入另一个账户。我已经知道如何取款和存款，我只是不知道如何把钱从一个帐户转到另一个帐户。以下是迄今为止我的传输方法代码：

import java.text.NumberFormat;
public class Account
{
    private NumberFormat fmt = NumberFormat.getCurrencyInstance();
    private final double RATE = 0.035; // interest rate of 3.5%
    private long acctNumber;
    private double balance;
    private String name;
    //-----------------------------------------------------------------
    // Sets up the account by defining its owner, account number,
    // and initial balance.
    //-----------------------------------------------------------------
    public Account (String owner, long 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;
    }

    public double transfer (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;

         //What should I put here to deposit the amount into another account?

        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;
    }

    //-----------------------------------------------------------------
    // Adds interest to the account and returns the new balance.
    //-----------------------------------------------------------------
    public double addInterest ()
    {
        balance += (balance * RATE);
        return balance;
    }
    //-----------------------------------------------------------------
    // Returns the current balance of the account.
    //-----------------------------------------------------------------
    public double getBalance ()
    {
        return balance;
    }
    //-----------------------------------------------------------------
    // Returns the account number.
    //-----------------------------------------------------------------
    public long 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));
    }
}

导入java.text.NumberFormat；
公共类帐户
{
私有NumberFormat fmt=NumberFormat.getCurrencyInstance（）；
私人最终双倍利率=0.035；//利率为3.5%
私人长帐号；
私人双平衡；
私有字符串名称；
//-----------------------------------------------------------------
//通过定义帐户的所有者、帐号、，
//和初始余额。
//-----------------------------------------------------------------
公共帐户（字符串所有者、长帐户、双首字母）
{
名称=所有者；
账户编号=账户；
余额=初始值；
}
//-----------------------------------------------------------------
//验证交易，然后存入指定金额
//存入帐户。返回新的余额。
//-----------------------------------------------------------------
公众双倍存款（双倍金额）
{
如果（金额<0）//存款值为负数
{
System.out.println（）；
System.out.println（“错误：存款金额无效。”）；
System.out.println（账号+“”+格式（金额））；
}
其他的
余额=余额+金额；
收益余额；
}
//-----------------------------------------------------------------
//验证交易，然后提取指定金额
//从帐户返回。返回新的余额。
//-----------------------------------------------------------------
公共双支取（双倍金额，双倍费用）
{
金额+=费用；
如果（金额<0）//提取值为负
{
System.out.println（）；
System.out.println（“错误：提取金额无效。”）；
System.out.println（“账户：+账号”）；
System.out.println（“请求：+fmt.格式（金额））；
}
其他的
如果（金额>余额）//取数超过余额
{
System.out.println（）；
System.out.println（“错误：资金不足”）；
System.out.println（“账户：+账号”）；
System.out.println（“请求：+fmt.格式（金额））；
System.out.println（“可用：“+fmt.format（balance））；
}
其他的
余额=余额-金额；
收益余额；
}
公开双倍转账（双倍金额，双倍费用）
{
金额+=费用；
如果（金额<0）//提取值为负
{
System.out.println（）；
System.out.println（“错误：提取金额无效。”）；
System.out.println（“账户：+账号”）；
System.out.println（“请求：+fmt.格式（金额））；
}
其他的
如果（金额>余额）//取数超过余额
{
System.out.println（）；
System.out.println（“错误：资金不足”）；
System.out.println（“账户：+账号”）；
System.out.println（“请求：+fmt.格式（金额））；
System.out.println（“可用：“+fmt.format（balance））；
}
其他的
余额=余额-金额；
//我应该在这里存些什么把钱存入另一个帐户？
如果（金额<0）//存款值为负数
{
System.out.println（）；
System.out.println（“错误：存款金额无效。”）；
System.out.println（账号+“”+格式（金额））；
}
其他的
余额=余额+金额；
}
//-----------------------------------------------------------------
//向帐户添加利息并返回新余额。
//-----------------------------------------------------------------
公共双addInterest（）
{
余额+=（余额*比率）；
收益余额；
}
//-----------------------------------------------------------------
//返回帐户的当前余额。
//-----------------------------------------------------------------
公共双getBalance（）
{
收益余额；
}
//-----------------------------------------------------------------
//返回帐号。
//-----------------------------------------------------------------
公共长getAccountNumber（）
{
返回账号；
}
//-----------------------------------------------------------------
//以字符串形式返回帐户的单行说明。
//-----------------------------------------------------------------
公共字符串toString（）
{
返回（账号+“\t”+名称+“\t”+格式（余额））；
}
}

您的转账方式没有任何用途

transfer

应该是主类中实例化帐户的方法。转让的例子是

public static void main(String[] args)
{
    // This creates two different accounts :)
    Account a = new Account("userA", 123, 200);
    Account b = new Account("userB", 234, 500);

    // Tranfer
    a.withdraw(100, 5);
    System.out.println(a.getBalance());
    b.deposit(100);
    System.out.println(b.getBalance());
}

把它变成一种方法

public static void transfer (Account from, Account to, double amount, double fee)
{
    from.withdraw(amount, fee);
    to.deposit(amount);
}

编辑

如果我正确理解了你的第二个问题，你想创建一个默认帐户吗？如果我误解了，你能提供更多的细节吗

import java.text.NumberFormat;
public class Account
{
    private NumberFormat fmt = NumberFormat.getCurrencyInstance();
    private final double RATE = 0.035; // interest rate of 3.5%
    private long acctNumber;
    private double balance;
    private String name;
    //-----------------------------------------------------------------
    // Sets up the account by defining its owner, account number,
    // and initial balance.
    //-----------------------------------------------------------------
    public Account (String owner, long account, double initial)
    {
        name = owner;
        acctNumber = account;
        balance = initial;
    }
    public Account()
    {
        // This would be the default constructor and default account
        name ="N/A";
        acctNumber = 0;
        balance = 0.0;
    }

    //-----------------------------------------------------------------
    // 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;
    }
    //-----------------------------------------------------------------
    // Returns the current balance of the account.
    //-----------------------------------------------------------------
    public double getBalance ()
    {
        return balance;
    }
    //-----------------------------------------------------------------
    // Returns the account number.
    //-----------------------------------------------------------------
    public long 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));
    }
}

public class test
{
    public static void main(String[] args)
    {
        // Created here
        Account defaultAccount = new Account();
        Account a = new Account("userA", 123, 200);
        Account b = new Account("userB", 234, 500);

        System.out.println(defaultAccount.getBalance());
        // Tranfer
        a.withdraw(100, 5);
        System.out.println(a.getBalance());
        b.deposit(100);
        System.out.println(b.getBalance());
    }

    public static void transfer (Account from, Account to, double amount, double fee)
    {
        from.withdraw(amount, fee);
        to.deposit(amount);
    }
}