我正在做一个增强的BankAccount类，以查看抽象和封装如何使软件发生演变。
现在我知道我下面的程序还没有完成，但是我想将帐号移到课程之外。
如果我不希望将帐号移到课程之外，那意味着我必须创建一个全新的课程。我知道一个程序每个java文件可以有多个类，但只有一个可以公开，我只是不知道我是否真的需要它。我应该将我的帐号的新班级设为私有吗？如果可以的话，我可以把它放到最后吗？我不知道该怎么办！很抱歉，我不断问我的教授，但是他绕着这个话题弹跳而从不回答关于班级的问题！
我是java的新手，所以不要给我校正的整个代码！我乐意去学
这是老师提供给我的程序（不完整）：
import java.util.Random;
/**
* Bank Account Class
* @author Morgan
* @version 1.1
*
*/
public class BankAccounts {
//data members
private double balance; // account balance
private int acctNum; // account number
private byte acctType; // types of account: 1 for Checking; 2 for savings
private int currentNumberOfTransactions; // current number of transactions per month
private double perTransactionFlatFee; // charge per transaction - depends on type of account
private static Random generator = new Random(System.currentTimeMillis()); //create random number generate object
private final static int CHECKING_MAX_NUMBER_OF_TRANSACTIONS_PER_MONTH = 5;
private final static int SAVINGS_MAX_NUMBER_OF_TRANSACTIONS_PER_MONTH = 2;
/**
* default constructor - initializes account balance and account number
*/
private BankAccounts(){
balance = 0.0; // initialize account balance
// generate random number accordingly and assign to account number
acctNum = generator.nextInt(1000) + 9999;
currentNumberOfTransactions = 0; // initialize
perTransactionFlatFee = 0.0; // initialize
}
/**
* constructor with current balance; initialize account number
* @param balance initial account balance
* @param type type of account (1 for Checking; 2 for Savings)
*/
public BankAccounts(double balance, byte type, int acctNum?){
this(); // use default constructor
this.balance = balance; // set initial balance
acctType = type; // set account type
switch (type){
case 1: perTransactionFlatFee = 0.10; break;
case 2: perTransactionFlatFee = 0.20; break;
}
}
/**
* constructor with account number; initialize balance
* @param type type of account (1 for Checking; 2 for Savings)
*/
public BankAccounts(byte type){
this(); // use default constructor
acctType = type; // set account type
switch (type){
case 1: perTransactionFlatFee = 0.10; break;
case 2: perTransactionFlatFee = 0.20; break;
}
}
/**
* getter to return current balance
* @return current account balance
*/
public double getBalance() {
return balance;
}
/**
* deposit into account
* @param amount amount to deposit; not more than 10,000
* @return true or false
*/
public void deposit(double amount){
// deposit amount - deduct per transaction fee based on type of account
}
/**
* withdraw from account
* @param amount amount to withdraw; not more than 10,000
* @return true or false
*/
public void withdraw(double amount) {
// withdraw amount - deduct per transaction fee based on type of account
}
private String getAcctType() {
String ret = "";
switch(acctType){
case 1: ret = "Checking"; break;
case 2: ret = "Savings"; break;
}
return ret;
}
/**
* Resets the current number of transactions to 0
* @param bankAccount Account to reset current number of transactions
*/
public static void reSetAccount(BankAccounts bankAccount){
bankAccount.currentNumberOfTransactions = 0;
}
/**
* Deducts the applicable monthly charges from the account balance.
* May lead to negative balance.
* @param bankAccount Account to apply the monthly charge
* @param chargeAmt Amount to charge if maximum allowable transactions have been exceeded
*/
public static void deductMonthlyCharges(BankAccounts bankAccount, double chargeAmt){
// deduct from balance the chargeAmt if applicable maximum allowable transactions have been exceeded
balance = balance - chargeAmt
// reset current number of transactions
//add my code here
System.out.println("\n\nCharges applied successfully.");
}
/**
* Prints an account information - Account number, type, balance, and current number of transactions
*/
public void print(){
System.out.println("\n\nAccount Number: " + acctNum + "\nAccount Type: " + getAcctType() +
"\nBalance: " + balance + "\nCurrent Number of Transactions: " + currentNumberOfTransactions);
}
}
最佳答案
对于您的情况，我建议使AccountNumber成为BankAccount的静态嵌套类-
public class BankAccounts {
public static class AccountNumber {
// your class declaration
}
// other methods/properties
}
如果任何其他类的对象需要访问您的
AccountNumber实例，则可以将其公开。如果不是这种情况，则可以将其设为私有。这样，只有BankAccounts成员才能实例化AccountNumber对象。在示例程序中，您的帐号似乎非常简单（只是一个
int）。对于这么简单的事情，创建一个单独的类太过分了。