我正在创建一个项目，允许用户创建，删除或显示银行账户以及存款，取款或打印交易。
当用户提供帐户ID时，我不知道如何使用扫描仪存取，取款和打印交易。
主要
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
BankProcess bankProcess = new BankProcess();
TransactionProcess transactionProcess = new TransactionProcess();
Bank bank = new Bank();
BankAccount bankAccount = new BankAccount();
int input = 0;
int selection = 0;
while (input == 0) {
System.out.println("");
System.out.println("Please choose one of the following: ");
System.out.println("[1] Create an account");
System.out.println("[2] Print all existing accounts");
System.out.println("[3] Delete an account");
System.out.println("[4] Deposit");
System.out.println("[5] Withdraw");
System.out.println("[6] Print transactions");
System.out.println("[0] Exit");
selection = scan.nextInt();
switch (selection) {
case 0:
System.out.println("Exit Successful");
System.exit(0);
case 1:
System.out.println("'[1] Create an account' has been selected.");
System.out.print("Account Id: ");
int accountId = scan.nextInt();
scan.nextLine();
System.out.print("Holder Name: ");
String holderName = scan.nextLine();
System.out.print("Holder Address: ");
String holderAddress = scan.nextLine();
System.out.print("Opening Balance: ");
double openingBalance = scan.nextDouble();
System.out.print("Open Date: ");
String openDate = scan.next();
bankAccount = new BankAccount(accountId, holderName, openingBalance, holderAddress, openDate);
bank.setAccounts(bankProcess.openNewAccount(bank.getAccounts(), bankAccount));
System.out.println("Successfully Added.");
break;
case 2:
System.out.println("'[2] Display all existing accounts' has been selected");
System.out.println("-----------------------------------------------------");
bank.getAccounts().forEach((i, b) - > System.out.println(b));
System.out.println("-----------------------------------------------------");
break;
case 3:
System.out.println("[3] Delete an account has been selected");
System.out.println("Enter the account ID: ");
bank.removeAccounts(bankProcess.openNewAccount(bank.getAccounts(), bankAccount));
break;
case 4:
System.out.println("[4] Deposit has been selected");
break;
case 5:
System.out.println("[5] Withdraw has been selected");
break;
case 6:
System.out.println("[6] Print Transaction has been selected");
break;
default:
System.out.println("Your choice was not valid!");
}
}
}
班级银行
public class Bank {
private TreeMap < Integer, BankAccount > bankAccounts = new TreeMap < Integer, BankAccount > ();
public TreeMap < Integer, BankAccount > getAccounts() {
return bankAccounts;
}
public void setAccounts(TreeMap < Integer, BankAccount > accounts) {
this.bankAccounts = accounts;
}
public void removeAccounts(TreeMap < Integer, BankAccount > accounts) {
this.bankAccounts = accounts;
}
}
班级BankProcess
public class BankProcess {
// return the Updated list of BankAccounts
public TreeMap < Integer, BankAccount > openNewAccount(TreeMap < Integer, BankAccount > bankAccounts, BankAccount bankAccount) {
//Get the List of existing bank Accounts then add the new BankAccount to it.
bankAccounts.put(bankAccount.getAccountId(), bankAccount);
return bankAccounts;
}
public TreeMap < Integer, BankAccount > removeAccount(TreeMap < Integer, BankAccount > bankAccounts, BankAccount bankAccount) {
bankAccounts.remove(bankAccount.getAccountId(), bankAccount);
return bankAccounts;
}
}
班级BankAccount
public class BankAccount {
private int accountId;
private String holderName;
private String holderAddress;
private String openDate;
private double currentBalance;
private List < Transaction > transactions = new ArrayList < Transaction > ();
//Provide Blank Constructor
public BankAccount() {}
//Constructor with an arguments.
public BankAccount(int accountNum, String holderNam, double currentBalance, String holderAdd, String openDate) {
this.accountId = accountNum;
this.holderName = holderNam;
this.holderAddress = holderAdd;
this.openDate = openDate;
this.currentBalance = currentBalance;
}
// Always Provide Setter and Getters
public int getAccountId() {
return accountId;
}
public void setAccountId(int accountId) {
this.accountId = accountId;
}
public String getHolderName() {
return holderName;
}
public void setHolderName(String holderName) {
this.holderName = holderName;
}
public String getHolderAddress() {
return holderAddress;
}
public void setHolderAddress(String holderAddress) {
this.holderAddress = holderAddress;
}
public String getOpenDate() {
return openDate;
}
public void setOpenDate(String openDate) {
this.openDate = openDate;
}
public double getCurrentBalance() {
return currentBalance;
}
public void setCurrentBalance(double currentBalance) {
this.currentBalance = currentBalance;
}
public List < Transaction > getTransactions() {
return transactions;
}
public void setTransactions(List < Transaction > transactions) {
this.transactions = transactions;
}
public String toString() {
return "\nAccount number: " + accountId + "\nHolder's name: " + holderName + "\nHolder's address: " + holderAddress + "\nOpen Date: " + openDate + "\nCurrent balance: " + currentBalance;
}
}
类交易
public class Transaction {
private int transactionId;
private String transactionType;
private double transactionAmount;
private double moneyBeforeTransaction;
private double moneyAfterTransaction;
public Transaction() {}
public Transaction(int transactionId, String transactionType, double transactionAmount, double moneyBeforeTransaction) {
this.transactionId = transactionId;
this.transactionType = transactionType;
this.transactionAmount = transactionAmount;
this.moneyBeforeTransaction = moneyBeforeTransaction;
}
public int getTransactionId() {
return transactionId;
}
public void setTransactionId(int transactionId) {
this.transactionId = transactionId;
}
public String getTransactionType() {
return transactionType;
}
public void setTransactionType(String transactionType) {
this.transactionType = transactionType;
}
public double getTransactionAmount() {
return transactionAmount;
}
public void setTransactionAmount(double transactionAmount) {
this.transactionAmount = transactionAmount;
}
public double getMoneyBeforeTransaction() {
return moneyBeforeTransaction;
}
public void setMoneyBeforeTransaction(double moneyBeforeTransaction) {
this.moneyBeforeTransaction = moneyBeforeTransaction;
}
public double getMoneyAfterTransaction() {
return moneyAfterTransaction;
}
public void setMoneyAfterTransaction(double moneyAfterTransaction) {
this.moneyAfterTransaction = moneyAfterTransaction;
}
//Override the toString() method of String ?
public String toString() {
return "Transaction ID : " + this.transactionId +
" Transaction Type : " + this.transactionType +
" Transaction Amount : " + this.transactionAmount +
" Money Before Transaction : " + this.moneyBeforeTransaction +
" Money After Transaction : " + this.moneyAfterTransaction;
}
}
类TransactionProcess
public class TransactionProcess {
//Always Provide another class for process.
//Pass the bankAccount of the user
public void deposit(BankAccount bankAccount, double depositAmount) {
//Get the CurrentBalance
double currentBalance = bankAccount.getCurrentBalance();
//First Argument : set the Id of transaction
//Second Argument : set the Type of Transaction
//Third Argument : set the TransactionAmount
//Fourth Argument : set the Balance Before the transaction (for record purposes)
Transaction transaction = new Transaction(bankAccount.getTransactions().size(), "Deposit", depositAmount, currentBalance);
if (depositAmount <= 0) {
System.out.println("Amount to be deposited should be positive");
} else {
//Set the updated or transacted balance of bankAccount.
bankAccount.setCurrentBalance(currentBalance + depositAmount);
//then set the MoneyAfterTransaction
transaction.setMoneyAfterTransaction(bankAccount.getCurrentBalance());
//after the transaction add it to the list of Transaction of bankAccount
bankAccount.getTransactions().add(transaction);
}
}
// Explanation same as above
public void withdraw(BankAccount bankAccount, double withdrawAmount) {
double currentBalance = bankAccount.getCurrentBalance();
Transaction transaction = new Transaction(bankAccount.getTransactions().size(), "Withdraw", withdrawAmount, currentBalance);
if (withdrawAmount <= 0) {
System.out.println("Amount to be withdrawn should be positive");
} else {
if (currentBalance < withdrawAmount) {
System.out.println("Insufficient balance");
} else {
bankAccount.setCurrentBalance(currentBalance - withdrawAmount);
transaction.setMoneyAfterTransaction(bankAccount.getCurrentBalance());
bankAccount.getTransactions().add(transaction);
}
}
}
}
答案 0 :(得分：0)
存款或撤回等操作的工作方式几乎相同，所以现在让我们专注于存款。
您已经拥有适当的开关案例：
case 4: {
// deposit
break;
}
（顺便说一句：大括号{和}在这里不是强制性的，它们只是帮助隔离代码，因此更容易阅读）
反正;要在银行帐户上存款，您首先需要帐号，然后您需要从银行获取帐户
case 4: {
int accountNumber = scan.nextInt(); // user types account number
TreeMap <Integer, BankAccount> bankAccounts = bank.getAccounts(); // bank returns all accounts (this is quite an insecure operation, it would be better to add a method to the bank class that returns only one account when passing the accountNumber
BankAccount bankAccount = bankAccounts.get(accountNumber);
break;
}
使用方法bank.getAccounts不是一个好的设计，因为该方法将从银行返回所有帐户。最好在班级Bank中使用一个返回单个帐户的方法。
public class Bank{
// ...
public BankAccount getAccount(Integer accountNumber){
return bankAccounts.get(accountNumber);
}
}
因为这将封装逻辑以将一个帐户检索到Bank类。在那里你还可以添加一些错误处理逻辑，例如当帐号无效时。
因此，此时您拥有用户的帐户，并且您知道用户想要存入一些钱。你只需要问他想要存入多少钱。再次使用扫描仪让用户输入金额。
现在您已获得BankAccount以及Transaction或更高TransactionProcess
TransactionProcess transactionProcess = new TransactionProcess(); // use the standard constructor to create an empty transactionProcess
transactionProcess.deposit(bankAccount, amount);
如果我理解您的程序正确，方法deposit将已使用用户的BankAccount并在为帐户创建交易时添加资金。我对么？那你实际上已经完成了。
将switch-chase 4的代码放在一起，如果有效，请使用类似的逻辑来实现withdraw。
我希望这有帮助！
//编辑// 以回答您的其他问题，这就是我的想法：
在你的BankAccount课程中添加如下方法：
public void addTransaction(Transaction transaction){
if(transactions.size() >= 6){ // test if the list has 6 or more transactions saved
transactions.remove(0); // if so, then remove the first (it's the oldest)
}
transactions.add(transaction); // the new transaction is always added, no matter how many other transactions there are already in the list
}
这只是一个例子，但我认为你应该能够像这样控制每个银行账户的交易金额。此外，您现在可以简化通话：查看deposit课程中TransactionProcess方法的最后一行。你打电话给
bankAccount.getTransactions().add(transaction); // takes the bank account, retrieves the list of transactions from the bank account and adds a transaction to the list
使用新方法addTransaction，您现在可以像这样编写它：
bankAccount.addTransaction(transaction); // adds a transaction to the bank account
更清洁，你不觉得吗？现在，您可以将所有逻辑用于管理和添加新方法中的事务:)