java - 如何连接不同类中的多个ArrayList。 (java银行程序)

Question

我参与了一项小组作业，我们应该创建一个银行程序。这是我们第一次用java编程。我们陷入困境，无法弄清楚如何连接我们的客户和帐户类别。它们都由 ArrayList 组成，我们希望客户数组列表包含帐户。这样，如果我们删除某个客户，属于该客户的帐户也将被删除。谁能插入我们朝正确的方向前进？

这是我们的主类，其中包含银行菜单:

package bank6;

import java.util.Scanner;
import java.util.HashMap;
import java.util.Map;


public class Bankmenu {

public static void main(String[] args) {

    Scanner input = new Scanner(System.in);
    Customer client = new Customer();
    Account bank = new Account();
    Account accs = new Account();


    Customer cust1, cust2, cust3;
    cust1 = new Customer("8905060000", "Henrik");
    cust2 = new Customer("8910210000", "Emelie");
    cust3 = new Customer("8611040000", "Fredrik");

    bank.addNewAccount(cust1);
    bank.addNewAccount(cust2);
    bank.addNewAccount(cust3);

    client.addCustomerAr(cust1);
    client.addCustomerAr(cust2);
    client.addCustomerAr(cust3);

    int ChoiceOne = 0;
    int CustChoice;
    int currentCustomer;
    int currentAccount;
    int amountC;
    int amountD;
    int editCust;
    String personNummer = null;

    String Pnr = "0";
    int AdminChoice;

    /*prompts the user to set ChoiceOne equal to 1 or 2. Hasnextint checks
     if the input is an int. else asks for new input. */
    while (ChoiceOne != 1 && ChoiceOne != 2) {
        System.out.println("Press 1 to login as customer or 2 to login as admin ");
        if (input.hasNextInt()) {
            ChoiceOne = input.nextInt();
            System.out.println();

        } else {
            System.out.println("You must enter number 1 or number 2");
            input.next();
        }//ends else

    }//ends while

    /*
     If the user chooses 1 in the previous question, the user will be sent to
     the interface for the customer. User is then asked to enter his social
     security number and this number will be checked using the Luhn algoritm. Since
     the scanner input is already used we added a new Scanner calleds nexLine
     to deal with custPnr as a string.
     (http://stackoverflow.com/questions/5032356/using-scanner-nextline)
     */
    if (ChoiceOne == 1) {
        //boolean quit=false;

        while ("0".equals(Pnr)) {
            //   System.out.println("Welcome customer. Please login by using your birthdate (yymmddnnnn) ");
            //  Scanner nextLine = new Scanner(System.in);
            //  Pnr = nextLine.nextLine();
            //Luhn.checkLogin(Pnr);
            //Här måste en kontroll med Luhn algoritmen göras.
            // getUserBirthdate();
            boolean CorrectBirthDate = false;

            while (CorrectBirthDate == false) {
                System.out.println("Please enter your birthdate");
                Scanner inception = new Scanner(System.in);
                personNummer = inception.next();
                CorrectBirthDate = Luhn.checkLogin(personNummer);

                if (CorrectBirthDate == false) {
                    System.out.println("Incorrect birthdate. You will be prompted to type it again");
                }
            }
            break;
            /*      }

             Sets "quit" to false and executes quit=true if customer chooses case 0
             */
        }
        boolean quit = false;
        do {
            // boolean quit = false;
            //System.out.println();
            System.out.println("Logged on as " + personNummer);
            System.out.println("1. deposit money");
            System.out.println("2. Withdraw money");
            System.out.println("3. Check balance");
            System.out.print("Your choice, 0 to quit: ");

            CustChoice = input.nextInt();

            switch (CustChoice) {
                case 1: //Deposit money
                    System.out.println(bank.getAccountNumbersFor(personNummer));
                    System.out.println("Enter account number:");
                    currentAccount = input.nextInt();
                    System.out.println("Enter amount to deposit:");
                    amountC = input.nextInt();
                    System.out.println(bank.creditAccount(currentAccount, amountC));
                    System.out.println(bank.getAccountNumbersFor("Henrik"));
                    break;
                case 2://Withdraw money
                    // System.out.println(bank.getAccNosFor(custPnr));
                    bank.getAccountNo();
                    System.out.println("Enter account number:");
                    currentAccount = input.nextInt();
                    System.out.println("Enter amount to withdraw:");
                    amountD = input.nextInt();
                    System.out.println(bank.debitAccount(currentAccount, amountD));
                    System.out.println(bank.getAccountNumbersFor("Henrik"));
                    break;
                case 3://Check ballance and accounts
                    System.out.println(bank.getAccountNumbersFor("Henrik"));
                    break;
                case 0:
                    quit = true;
                    break;
                default:
                    System.out.println("Wrong choice.");
                    break;
            }
            System.out.println();
        } while (!quit);
        System.out.println("Bye!");

    }//ends if
    else if (ChoiceOne == 2) {

        while ("0".equals(Pnr)) {
            boolean CorrectBirthDate = false;

            while (CorrectBirthDate == false) {
                System.out.println("Please enter your birthdate");
                Scanner inception = new Scanner(System.in);
                personNummer = inception.next();
                CorrectBirthDate = Luhn.checkLogin(personNummer);

                if (CorrectBirthDate == false) {
                    System.out.println("Incorrect birthdate. You will be prompted to type it again");
                }
            }
            break;
        }

        //AdminpNr = input.nextInt();
        //Här måste en kontroll av AdminpNr göras med hjälp av Luhn.
        boolean quit = false;
        do {
            System.out.println("1. Add customer");
            System.out.println("2. Add account");
            System.out.println("3. List customer");
            System.out.println("4. List accounts");
            System.out.println("5. Remove customer");
            System.out.println("6. Remove account");
            System.out.print("Your choice, 0 to quit: ");
            AdminChoice = input.nextInt();

            switch (AdminChoice) {
                case 1://add customer
                    int i = 0;
                    do {
                        System.out.println("Skriv in nytt personnummer:");
                        Scanner scan = new Scanner(System.in);

                        Map<String, Customer> testCustomers = new HashMap<String, Customer>();
                        String name = scan.nextLine();

                        //System.out.println("Att arbeta på bank ska vara jobbigt, skriv in det igen:");
                        //String pnummer = scan.nextLine();
                        String pnummer = name;
                        System.out.println("Skriv in namn:");
                        String kundnamn = scan.nextLine();
                        Customer obj = new Customer(pnummer, kundnamn);
                        testCustomers.put(name, obj);
                        client.addCustomerAr(obj);
                        i++;
                    } while (i < 2);
                    break;
                case 2://add account
                    int i2 = 0;
                    do {
                        System.out.println("Skriv in nytt personnummer:");
                        Scanner scan = new Scanner(System.in);

                        Map<Long, Account> testAccs = new HashMap<Long, Account>();
                        Long name = scan.nextLong();

                        //System.out.println("Skriv in personnummer igen:");
                        Long own = name;

                        long bal = 0;
                        Account obt = new Account(own, bal);
                        testAccs.put(name, obt);
                        accs.addAccAr(obt);
                        i2++;
                    } while (i2 < 2);
                    break;
                case 3:// List customer and accounts
                    for (String info : client.getAllClients()) {
                        System.out.println(info);
                    }
                    break;
                case 4:
                    for (Long infoAcc : accs.getAllAccounts()) {
                        System.out.println(infoAcc);
                    }
                    break;
                case 5:
                    // ta bort kund
                    break;
                case 6:
                    // ta bort konto
                    break;
                case 0:
                    quit = true;
                    break;
                default:
                    System.out.println("Wrong choice.");
                    break;
            }

            System.out.println();
        } while (!quit);

        System.out.println("Bye!");

    }//ends else if

}//ends main
 /* private static void getUserBirthdate() {
 boolean CorrectBirthDate = false;

 while (CorrectBirthDate == false) {
 System.out.println("Please enter your birthdate");
 Scanner inception = new Scanner (System.in);
 String personNummer = inception.next();
 CorrectBirthDate = Luhn.checkLogin(personNummer);

 if (CorrectBirthDate == false) {
 System.out.println("Incorrect birthdate. You will be prompted to type it again");
 }
 }
 }
 */

}//ends class

这是我们的 Account 类；

package bank6;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.ListIterator;


public class Account {

private ArrayList accounts;
private Object lastAcc;
public String customerSocial;
private Integer balance;
private Integer accountNumber;
private Customer owner;
private Account Customer6; // Association customer/account.
private ArrayList<Account> myAccounts = new ArrayList<Account>();
public Integer deposit;
public Integer withdraw;

static Integer accountNo = 1010;
private Long persnr;
private long balans = 0;

/*Constructor.. A account cannot exist unless it is owned by a customer*/
public Account(Customer owner, Integer balance) {
    this.owner = owner;
    this.balance = balance;
    accountNumber = accountNo++;
}

public Account() {
    accounts = new ArrayList();
}

public Account(Long persnr, long balans) {
    this.persnr = persnr;
    this.balans = balans;
    accountNumber = accountNo++;

}

public Integer getAccountNo() {
    return accountNumber;
}

public String getOwner() {
    return owner.getName();
}

public Customer getOwn() {
    return owner;
}

public Integer getBalance() {
    return balance;
}

//credits the account with an amount of money and returns a string
public String credit(Integer anAmount) {
    balance += anAmount;
    //  return "Account number " + accountNumber + " Has been credited with "+anAmount + " kr.";
    return "   " + anAmount + " kr has been deposited to " + accountNumber + "\n";
}

public boolean canDebit(Integer anAmount) {
    return anAmount <= balance;
}

public String debit(Integer anAmount) {

    if (this.canDebit(anAmount)) {
        balance -= anAmount;
        return "   " + anAmount + " kr has been withdrawn from " + accountNumber + "\n";
    } else {
        return "Account number" + accountNo + "has insufficient funds to debit"
                + anAmount;
    }

}

public void addNewAccount(Customer customer) {
    accounts.add(new Account(customer, 0));
    lastAcc = accounts.get(accounts.size() - 1);
    System.out.println("*** New account created. ***" //+ lastAcc 
            + "\n");

}

public String removeAccount(int accountNumber) {
    boolean found = false;
    String results = "";
    ListIterator iter = accounts.listIterator();
    while (iter.hasNext() && found) {

        Account account = (Account) iter.next();

        if (account.getAccountNo() == accountNumber) {
            found = true; //there is a match stop the loop

            if (account.getBalance() == 0) {
                iter.remove();//remove this account object
                results = "Account number " + accountNumber + " has been removed";
            } else {
                results = "Account number " + accountNumber + " cannot be removed"
                        + "as it has a balance of: " + account.getBalance();
            }
        }//ends if there is a match
    }// end while loop

    if (!found) {
        results = "No such account";
    }
    return results;

}

public String creditAccount(int accountNumber, Integer anAmount) {

    boolean found = false;
    String results = "";
    ListIterator iter = accounts.listIterator();
    while (iter.hasNext() && !found) {
        Account account = (Account) iter.next();
        if (account.getAccountNo() == accountNumber) {
            results = account.credit(anAmount);
            found = true;//stop the loop
        }
    }
    if (!found) {
        results = "No such customer";
    }
    return results;
}

public String debitAccount(int accountNumber, Integer anAmount) {
    boolean found = false;
    String results = "";
    ListIterator iter = accounts.listIterator();
    while (iter.hasNext() && !found) {

        Account account = (Account) iter.next();
        if (account.getAccountNo() == accountNumber) {
            results = account.debit(anAmount);
            found = true;
        }
    }

    if (!found) {
        results = "No such Customer";
    }
    return results;
}

public String getAccountNumbersFor(String CustomerName) {
    String details = CustomerName + " has the followinng accounts: "
            + "\n\n";
    Iterator iter = accounts.iterator();

    //visit all of the accounts in the ArrayList
    while (iter.hasNext()) {
        Account account = (Account) iter.next();
        if (account.getOwner().equals(CustomerName)) {
            details += "   Account number " + account.getAccountNo()
                    + "     Balance " + account.getBalance() + "kr \n";

        }//ends if
    }//ends while
    return details;
}

public String bankAccounts() {
    String details = "ALL BANK ACCOUNTS" + "\n"
            + "-----------------" + '\n';

    if (accounts.size() == 0) {
        details += "There are no bank accounts";
    } else {
        Iterator iter = accounts.iterator();
        while (iter.hasNext()) {
            details += iter.next().toString() + '\n';
        }
    }
    return details;
}

@Override
public String toString() {

    return "Account " + accountNumber + ": " + owner
            + "\nBalance: " + balance + " kr.\n";
}

public Boolean authenticateUser(String login, String ssn) {
    if (Luhn.checkLogin(ssn)) {
        System.out.println("User authenticated");
        return true;
    } else {
        System.out.println("Authentication refused");
        return false;
    }
}

public void addAccAr(Account myAccount) {
    myAccounts.add(myAccount);
}


public Long getBalanceToLong() {
    long balTemp = balans;
    return balTemp;
}

public Long getPnTorLong() {

    return persnr;
}

public Long getAccNoLong() {

    long accTemp = accountNumber;
    return accTemp;
}

public ArrayList<Long> getAllAccounts() {
    ArrayList<Long> allAccounts = new ArrayList<>();
    System.out.println("ALL ACCOUNTS\n-----------");
    for (Account myAccount : myAccounts) {
        allAccounts.add(myAccount.getAccNoLong());
        allAccounts.add(myAccount.getPnTorLong());
        allAccounts.add(myAccount.getBalanceToLong());
    }
    return allAccounts;

}
/*
 public ArrayList<String> getMyAccounts() {
 ArrayList<String> ownAccounts = new ArrayList<>();
 System.out.println("MY ACCOUNTS\n-----------");
 for (Account myAccount : myAccounts) {
 ownAccounts.add(myAccount.getAccNoStr());
 ownAccounts.add(myAccount.getBalanceToStr());
 }
 return ownAccounts;

 }*/
}

这是我们的客户类别

package bank6;

import java.util.ArrayList;


public class Customer {
 int custCounter;

//attribut
private Long socialNo;
private String name;
private ArrayList customers;
public Integer customerNumber;
static Integer custNo = 1;

private ArrayList<Customer> clients = new ArrayList<Customer>();
//konstruktor

public Customer(String socialStr, String name) {
    Long socialTemp = new Long(socialStr);
    this.name = name;
    this.socialNo = socialTemp;
    customerNumber = custNo++;

}//ends  konstruktor customer6

public Customer() {
    customers = new ArrayList();
}

/* Set methods*/
public void setName(String name) {
    this.name = name;
}

public void setsocialNo(Long socialNo) {
    this.socialNo = socialNo;
}

/* get methods */
public String getName() {
    return name;
}

public String getSocialNoStr() {
    String socialTemp = Long.toString(socialNo);
    return socialTemp;
}

public Long getSocialNo() {
    return socialNo;
}

/*toString() method*/
@Override
public String toString() {

    return "\n" + "Owner: " + name + " (" + socialNo + ")";
}

public void addAccCustAr() {

}

public void addCustomerAr(Customer client) {
    clients.add(client);
}

public ArrayList<String> getAllClients() {
    ArrayList<String> allClients = new ArrayList<>();
    System.out.println("ALL CLIENTS\n-----------");
    for (Customer client : clients) {
        allClients.add(client.getName());
        allClients.add(client.getSocialNoStr() + "\n");
    }
    return allClients;
    //add account
    //public void addAccount(account6 account){
    //    accounts.add(account);
    //}// ends adds account
    //remove account
    //public void removeAccount (account6 account) {
    //    accounts.remove(account);
    //}//ends remove account
}
}//ends public class

这是我们的 Luhn 类(class)

package bank6;

public class Luhn {

public static boolean checkLogin(String pnr) {

    if (pnr.length() != 10) {
        System.out.println("");
        return false;
    } else {

        int length = pnr.length();

        int sum = 0;
        int pos = length - 1;
        for (int i = 1; i <= length; i++, pos--) {

            char tmp = pnr.charAt(pos);
            int num = Integer.parseInt(String.valueOf(tmp));

            int produkt;
            if (i % 2 != 0) {
                produkt = num * 1;
            } else {
                produkt = num * 2;
            }
            if (produkt > 9) {
                produkt -= 9;
            }
            sum += produkt;
        }

        boolean korrekt = (sum % 10) == 0;

        if (korrekt) {
            System.out.println("Correct");
            return true;
        } else {
            System.out.println("Invalid");
            return false;
        }
    }
}
}

Answer 1

• 您的 Account 类已经有一个 Customer 字段 - 很好。
• 您应该给客户一个 ArrayList<Account>帐户字段。
• 并且还给客户 addAccount(Account acct)和removeAccount(Account acct)方法。
• 为什么客户有 ArrayList<Customer> field ？这没什么意义。客户是否应该持有其他客户的名单？为什么？出于什么目的？
• 为什么帐户有 private ArrayList<Account> myAccounts = new ArrayList<Account>(); ？这也没什么意义。一个账户应该持有一堆其他账户吗？再说一遍，目的是什么？
• Account 类在逻辑上应代表一个并且仅代表一个帐户。
• Customer 类也是如此 - 它在逻辑上应该仅代表一个客户。

如果您逻辑地思考事物，它们通常会结合在一起，并且代码的每个组件都应该有意义。如果没有，请询​​问为什么它在那里。

所以这段代码被破坏了:

Account bank = new Account();

//....

bank.addNewAccount(cust1);
bank.addNewAccount(cust2);
bank.addNewAccount(cust3);

因为您要将一堆客户添加到帐户对象中。看来您应该有另一个类，一个 Bank 类，它可以容纳 ArrayList<Customer> 。这难道没有道理吗？