Java 學習記錄44 — Autoboxing and Unboxing 小挑戰

小挑戰：

You job is to create a simple banking application.

There should be a Bank class

It should have an arraylist of Branches

Each Branch should have an arraylist of Customers

The Customer class should have an arraylist of Doubles (transactions)

Customer:

Name, and the ArrayList of doubles.

Branch:

Need to be able to add a new customer and initial transaction amount.

Also needs to add additional transactions for that customer/branch

Bank:

Add a new branch

Add a customer to that branch with initial transaction

Add a transaction for an existing customer for that branch

Show a list of customers for a particular branch and optionally a list

of their transactions

Demonstration autoboxing and unboxing in your code

Hint: Transactions

Add data validation.

e.g. check if exists, or does not exist, etc.

Think about where you are adding the code to perform certain actions

解答：

我的版本

Customer.java

import java.util.ArrayList;
public class Customer {
    private ArrayList<Double> transactions;
    private String name;
    public Customer(String name) {
        this.name = name;
        transactions = new ArrayList<Double>();
    }
    public static Customer createCustomer(String name) {
        return new Customer(name);
    }
    public String getName() {
        return name;
    }
    public ArrayList<Double> getTransactions() {
        return transactions;
    }
    public void transaction_record() {
        for (int i = 0; i < transactions.size(); i++) {
            System.out.println((i + 1) + " : " + transactions.get(i));
        }
    }
    public double countBalance() {
        double balance = 0;
        for (int i = 0; i < transactions.size(); i++) {
            balance += transactions.get(i).doubleValue();
        }
        return balance;
    }
}

Branch.java

import java.util.ArrayList;
public class Branch {
    private ArrayList<Customer> customers;
    private String BranchCode;
    public Branch(String BranchCode) {
        this.BranchCode = BranchCode;
        customers = new ArrayList<Customer>();
    }
    public static Branch createBranch(String BranchCode) {
        return new Branch(BranchCode);
    }
    public ArrayList<Customer> getCustomers() {
        return customers;
    }
    public String getBranchCode() {
        return BranchCode;
    }

    public void customersTransaction(Customer customerA, Customer customerB, Double amount) {
        customerA.getTransactions().add(-amount);
        customerB.getTransactions().add(amount);
    }
    public boolean addCustomer(Customer customer) {
        if (findCustomer(customer.getName()) >= 0) {
            System.out.println("customer is already on file.");
            return false;
        }
        customers.add(customer);
        double initial_amount = 10000;
        customer.getTransactions().add(initial_amount);
        return true;
    }
    public int findCustomer(String customerName) {
        for (int i = 0; i < customers.size(); i++) {
            Customer customer = customers.get(i);
            if (customer.getName().equals(customerName)) {
                return i;
            }
        }
        return -1;
    }
    public Customer queryCustomer(String customerName) {
        int position = findCustomer(customerName);
        if (position >= 0) {
            return customers.get(position);
        }
        return null;
    }
    public double checkBalance(String customerName) {
        Customer customer = queryCustomer(customerName);
        return customer.countBalance();
    }
    public void printCustomer() {
        System.out.println("Branch code(" + getBranchCode() + "), list of customer: ");
        if (customers.size() != 0) {
            for (int i = 0; i < customers.size(); i++) {
                System.out.println("No." + (i + 1) + " Customer: " + customers.get(i).getName());
                System.out.println("Transaction record: ");
                customers.get(i).transaction_record();
                System.out.println("Total balance: \n$" + customers.get(i).countBalance());
            }
        } else {
            System.out.println("Please add customer to branch.\nDon't have any customer now!");
        }
    }

}

Bank.java

import java.util.ArrayList;
public class Bank {
    private static String BankName;
    private static ArrayList<Branch> branches;
    public Bank(String bankName) {
        BankName = bankName;
        branches = new ArrayList<Branch>();
    }
    public static String getBankName() {
        return BankName;
    }
    public static ArrayList<Branch> getBranches() {
        return branches;
    }
    public boolean printBranches() {
        if (branches.size() == 0) {
            System.out.println("Please add branch first!\nDon't have any branch now.");
            return false;
        }
        System.out.println(getBankName() + " had " + branches.size() + " branches.");
        for (int i = 0; i < branches.size(); i++) {
            System.out.println(getBankName() + " No." + (i + 1) +
                    " branch code (" + branches.get(i).getBranchCode() + ")");
        }
        return true;
    }
    public boolean addNewCustomer(Branch branch, String customerName) {
        Customer customer = new Customer(customerName);
        return branch.addCustomer(customer);
    }
    public boolean addNewBranch(Branch branch) {
        if (findBranch(branch.getBranchCode()) >= 0) {
            System.out.println("That branch is already on file.");
            return false;
        }
        branches.add(branch);
        return true;
    }
    public int findBranch(String branchName) {
        for (int i = 0; i < branches.size(); i++) {
            Branch branch = branches.get(i);
            if (branch.getBranchCode().equals(branchName)) {
                return i;
            }
        }
        return -1;
    }

    public void printBranchCustomer(String BranchName) {
        if (queryBranch(BranchName) != null) {
            queryBranch(BranchName).printCustomer();
        } else {
            System.out.println("Couldn't find branch code (" + BranchName + ")");
        }
    }
    public Branch queryBranch(String BranchName) {
        int position = findBranch(BranchName);
        if (position >= 0) {
            return branches.get(position);
        }
        return null;
    }
    public boolean customersTransaction(Branch branchA, String customerA, Branch branchB, String customerB, Double amount) {
        if (branchA.queryCustomer(customerA) == null || branchB.queryCustomer(customerB) == null) {
            System.out.println("Customer didn't exist that branch.");
            return false;
        }
        Customer customer_A = branchA.queryCustomer(customerA);
        Customer customer_B = branchB.queryCustomer(customerB);
        if (branchA.checkBalance(customerA) >= amount) {
            branchA.customersTransaction(customer_A, customer_B, amount);
            return true;
        }
        System.out.println("Customer amount isn't enough!");
        return false;
    }

}

MainBank.java

import java.util.Scanner;
public class MainBank {
    private static Scanner scanner = new Scanner(System.in);
    private static Bank bank = new Bank("CityBank");
    public static void main(String[] args) {
        boolean quit = false;
        startBank();
        printActions();
        while (!quit) {
            System.out.println("------------------------------------");
            System.out.println("Enter number to action: ");
            int choice = scanner.nextInt();
            scanner.nextLine();
            switch (choice) {
                case 0:
                    quit = true;
                    System.out.println("Thank you, Good bye!");
                    break;
                case 1:
                    bank.printBranches();
                    break;
                case 2:
                    addNewBranch();
                    break;
                case 3:
                    addNewCustomer();
                    break;
                case 4:
                    addTransaction();
                    break;
                case 5:
                    printCustomer();
                    break;
                case 6:
                    printActions();
                    break;
            }
        }
    }
    private static void addNewBranch() {
        System.out.println("This function is addNewBranch");
        System.out.println("Enter new branch code: ");
        Branch branch = Branch.createBranch(scanner.nextLine());
        if (bank.addNewBranch(branch)) {
            System.out.println("Successful! New branch code (" + branch.getBranchCode() + ") be added");
        } else {
            System.out.println("Error! Cannot add branch code (" + branch.getBranchCode() + ") already had...");
        }
        System.out.println("function out!");
    }
    private static void addNewCustomer() {
        System.out.println("This function is addNewCustomer");
        if (bank.printBranches()) {
            System.out.println("Which branch need to add new customer?\nEnter branch code: ");
            String branchName = scanner.nextLine();
            Branch branch = bank.queryBranch(branchName);
            if (bank.findBranch(branchName) >= 0) {
                System.out.println("Enter new customer name: ");
                String customerName = scanner.nextLine();
                if (bank.addNewCustomer(branch, customerName)) {
                    System.out.println("Successful! New customer: " + customerName + " be added  to branch code: " + branchName);
                } else {
                    System.out.println("Cannot add new customer " + customerName + " to branch code " + branchName);
                }
            } else {
                System.out.println("Error! Branch(" + branchName + ") doesn't exist!");
            }
        }
        System.out.println("function out!");
    }
    private static void addTransaction() {
        System.out.println("This function is addTransaction");
        if (bank.printBranches()) {
            System.out.println("A pay $amount to B");
            System.out.println("Enter A customer branch code: ");
            String branchName = scanner.nextLine();
            Branch branchA = bank.queryBranch(branchName);
            System.out.println("Enter A customer name: ");
            String customerA = scanner.nextLine();
            System.out.println("Pay how much?");
            Double amount = scanner.nextDouble();
            scanner.nextLine();
            System.out.println("Enter B customer branch code: ");
            String branchNameB = scanner.nextLine();
            Branch branchB = bank.queryBranch(branchNameB);
            System.out.println("Enter B customer name: ");
            String customerB = scanner.nextLine();
            if (bank.customersTransaction(branchA, customerA, branchB, customerB, amount)) {
                System.out.println("Successful!");
            } else {
                System.out.println("Error");
            }
        }
        System.out.println("function out!");
    }
    private static void printCustomer() {
        System.out.println("This function is printCustomer");
        if (bank.printBranches()) {
            System.out.println("Which branch need to print all customer?\nEnter branch code: ");
            String branchName = scanner.nextLine();
            bank.printBranchCustomer(branchName);
        }
        System.out.println("function out!");
    }
    private static void printActions() {
        System.out.println("\nAvailable actions:\nPress number of list.");
        System.out.println("0  - to shutdown\n" +
                "1  - to print branches\n" +
                "2  - to add a new branch\n" +
                "3  - to add a new customer\n" +
                "4  - to add a transaction\n" +
                "5  - to print customer list of branch\n" +
                "6  - to print action.");
    }
    private static void startBank() {
        System.out.println("Start Bank app ------");
    }
}

這道題我沒有先看 Tim 的解答，靠自己修改前面的練習所寫，所以不一定符合題目要求

足足花了我 5 天來寫而且還是在我有參考 Mobile project 的情況

從剛開始光理解題目就很頭痛，到理解完題目開始寫一點

到寫完大部分開始調適代碼，卻發現數字竟然對不上

又開始東調西調代碼，到輸出結果終於能滿足自己的想法

這題目比較難的是 Bank 要有 Branch的Arraylis，而 Branch 又要有 Customer的Arraylis

要非常清楚自己寫的 method 要起什麼作用，要給哪個 Class 調用，要放入跟傳回哪種數據類型

寫完之後就會對數據的傳遞方式的理解，印象深入了許多

開始寫才發現，前面光用看的或照抄Tim的代碼，雖然當時覺得自己理解大部份內容了

但真的要寫的時候就一片空白，只好回去翻前面的練習，邊抄邊改成自己要的

補充一下，寫不出來也不用太在意，我看網友說連大公司的programmer也是會抄代碼來改

Tim version

Customer_TimVersion.java

import java.util.ArrayList;
public class Customer_TimVersion {
    private String name;
    private ArrayList<Double> transactions;
    public Customer_TimVersion(String name, double initialAmount) {
        this.name = name;
        transactions = new ArrayList<Double>();
        addTransaction(initialAmount);
    }
    public void addTransaction(double amount) {
        transactions.add(amount);
    }
    public String getName() {
        return name;
    }
    public ArrayList<Double> getTransactions() {
        return transactions;
    }
}

Branch_TimVersion.java

import java.util.ArrayList;
public class Branch_TimVersion {
    private String name;
    private ArrayList<Customer_TimVersion> customers;
    public Branch_TimVersion(String name) {
        this.name = name;
        customers = new ArrayList<Customer_TimVersion>();
    }
    public String getName() {
        return name;
    }
    public ArrayList<Customer_TimVersion> getCustomers() {
        return customers;
    }
    public boolean newCustomer(String customerName, double initialAmount) {
        if (findCustomer(customerName) == null) {
            customers.add(new Customer_TimVersion(customerName, initialAmount));
            return true;
        }
        return false;
    }
    public boolean addCustomerTransaction(String customerName, double amount) {
        Customer_TimVersion existingCustomer = findCustomer(customerName);
        if (existingCustomer != null) {
            existingCustomer.addTransaction(amount);
            return true;
        }
        return false;
    }
    private Customer_TimVersion findCustomer(String customerName) {
        for (int i = 0; i < customers.size(); i++) {
            Customer_TimVersion checkCustomer = customers.get(i);
            if (checkCustomer.getName().equals(customerName)) {
                return checkCustomer;
            }
        }
        return null;
    }
}

Bank_TimVersion.java

import java.util.ArrayList;
public class Bank_TimVersion {
    private String name;
    private ArrayList<Branch_TimVersion> branches;
    public Bank_TimVersion(String name) {
        this.name = name;
        branches = new ArrayList<Branch_TimVersion>();
    }
    public boolean addBranch(String branchName) {
        if (findBranch(branchName) == null) {
            branches.add(new Branch_TimVersion(branchName));
            return true;
        }
        return false;
    }
    public boolean addCustomer(String branchName, String customerName, double initialAmount) {
        Branch_TimVersion branch = findBranch(branchName);
        if (branchName != null && branch != null) {
            return branch.newCustomer(customerName, initialAmount);
        }
        return false;
    }
    public boolean addCustomerTransaction(String branchName, String customerName, double amount) {
        Branch_TimVersion branch = findBranch(branchName);
        if (branch != null) {
            return branch.addCustomerTransaction(customerName, amount);
        }
        return false;
    }
    private Branch_TimVersion findBranch(String branchName) {
        for (int i = 0; i < branches.size(); i++) {
            Branch_TimVersion Branch = branches.get(i);
            if (Branch.getName().equals(branchName)) {
                return Branch;
            }
        }
        return null;
    }
    public boolean listCustomer(String branchName, boolean showTransaction) {
        Branch_TimVersion branch = findBranch(branchName);
        if (branch != null) {
            System.out.println("Customer details for branch " + branch.getName());
            ArrayList<Customer_TimVersion> branchCustomers = branch.getCustomers();
            for (int i = 0; i < branchCustomers.size(); i++) {
                Customer_TimVersion branchCustomer = branchCustomers.get(i);
                System.out.println("Customer: " + branchCustomer.getName() + "[" + (i + 1) + "]");
                if (showTransaction) {
                    System.out.println("Transactions");
                    ArrayList<Double> transactions = branchCustomer.getTransactions();
                    for (int j = 0; j < transactions.size(); j++) {
                        System.out.println("[" + (j + 1) + "]" + "Amount " + transactions.get(j));
                    }
                }
            }
            return true;
        }
        return false;
    }
}

MainBank_TimVersion.java

public class MainBank_TimVersion {
    public static void main(String[] args) {
        Bank_TimVersion bank = new Bank_TimVersion("City Bank");
        bank.addBranch("New York");
        bank.addCustomer("New York", "Tim", 500.05);
        if(!bank.addCustomer("New York", "Tim", 500)){
            System.out.println("Already had");
        }
        bank.addCustomer("New York", "Tim", 500);
        bank.addCustomer("New York", "Jemmy", 170.56);
        bank.addCustomer("New York", "Zic", 320.22);
        bank.addBranch("Los Angel");
        bank.addCustomer("Los Angel", "Bonny", 126.54);
        bank.addCustomerTransaction("New York", "Tim", 36.66);
        bank.addCustomerTransaction("Los Angel", "Bonny", 36.66);
        bank.listCustomer("Los Angel", true);
        bank.listCustomer("New York", false);
        if(!bank.addCustomer("Sydney", "Brian", 6.66)){
            System.out.println("Error Sydney branch doesn't exist");
        }

    }

}

結果 Tim 做的功能比我想的少很多

但是寫的真漂亮，看起來就很舒服

於是我又把自己寫的修改了一下

修正版

Customer.java

import java.util.ArrayList;
public class Customer {
    private ArrayList<Double> transactions;
    private String name;
    public Customer(String name, double initialAmount) {
        this.name = name;
        transactions = new ArrayList<Double>();
        addTransaction(initialAmount);
    }
    public static Customer createCustomer(String name, double initialAmount) {
        return new Customer(name, initialAmount);
    }
    public String getName() {
        return name;
    }
    public ArrayList<Double> getTransactions() {
        return transactions;
    }
    public void addTransaction(double amount) {
        transactions.add(amount);
    }
    public void transaction_record() {
        for (int i = 0; i < transactions.size(); i++) {
            System.out.println((i + 1) + " : " + transactions.get(i));
        }
    }
    public double getBalance() {
        double balance = 0;
        for (Double transaction : transactions) {
            balance += transaction;
        }
        return balance;
    }
}

Branch.java

import java.util.ArrayList;
public class Branch {
    private ArrayList<Customer> customers;
    private String name;
    public Branch(String name) {
        this.name = name;
        customers = new ArrayList<Customer>();
    }
    public static Branch createBranch(String BranchCode) {
        return new Branch(BranchCode);
    }
    public String getName() {
        return name;
    }
    public boolean addCustomer(String customerName, double initialAmount) {
        if (findCustomer(customerName) >= 0) {
            return false;
        }
        customers.add(Customer.createCustomer(customerName, initialAmount));
        return true;
    }
    private int findCustomer(String customerName) {
        for (int i = 0; i < customers.size(); i++) {
            Customer customer = customers.get(i);
            if (customer.getName().equals(customerName)) {
                return i;
            }
        }
        return -1;
    }
    public Customer queryCustomer(String customerName) {
        int position = findCustomer(customerName);
        if (position >= 0) {
            return customers.get(position);
        }
        return null;
    }
    public void printCustomer() {
        System.out.println("Branch code [" + getName() + "] --- list of customer: ");
        if (customers.size() != 0) {
            for (int i = 0; i < customers.size(); i++) {
                System.out.println("No." + (i + 1) + " Customer: " + customers.get(i).getName());
                System.out.println("Transaction record: ");
                customers.get(i).transaction_record();
                System.out.println("Total balance: \n$" + customers.get(i).getBalance());
            }
        } else {
            System.out.println("Please add customer to branch.\nDon't have any customer now!");
        }
    }

}

Bank.java

import java.util.ArrayList;
public class Bank {
    private String name;
    private ArrayList<Branch> branches;
    public Bank(String name) {
        this.name = name;
        branches = new ArrayList<Branch>();
    }
    public String getName() {
        return name;
    }
    public boolean printBranches() {
        if (branches.size() == 0) {
            System.out.println("Please add branch first!\nDon't have any branch now.");
            return false;
        }
        System.out.println(getName() + " had " + branches.size() + " branches.");
        for (int i = 0; i < branches.size(); i++) {
            System.out.println(getName() + " No." + (i + 1) +
                    " branch code (" + branches.get(i).getName() + ")");
        }
        return true;
    }
    public boolean addNewCustomer(String branchName, String customerName, double initialAmount) {
        if (findBranch(branchName) >= 0) {
            Branch branch = queryBranch(branchName);
            if (branch.addCustomer(customerName, initialAmount)) {
                return true;
            }
        }
        return false;
    }
    public boolean addNewBranch(String branchName) {
        if (findBranch(branchName) >= 0) {
            return false;
        }
        branches.add(Branch.createBranch(branchName));
        return true;
    }
    private int findBranch(String branchName) {
        for (int i = 0; i < branches.size(); i++) {
            Branch branch = branches.get(i);
            if (branch.getName().equals(branchName)) {
                return i;
            }
        }
        return -1;
    }
    public Branch queryBranch(String BranchName) {
        int position = findBranch(BranchName);
        if (position >= 0) {
            return branches.get(position);
        }
        return null;
    }
    public void printBranchCustomer(String BranchName) {
        queryBranch(BranchName).printCustomer();
    }
    public boolean customersTransaction(String branchA, String customerA, String branchB, String customerB, Double amount) {
        if (findBranch(branchA) >= 0 && findBranch(branchB) >= 0) {
            Branch branch_A = queryBranch(branchA);
            Branch branch_B = queryBranch(branchB);
            if (branch_A.queryCustomer(customerA) != null && branch_B.queryCustomer(customerB) != null) {
                Customer customerPay = branch_A.queryCustomer(customerA);
                if (customerPay.getBalance() >= amount) {
                    customerPay.getTransactions().add(-amount);
                    Customer customerReceive = branch_B.queryCustomer(customerB);
                    customerReceive.getTransactions().add(amount);
                    return true;
                }
            }
        }
        return false;
    }

}

MainBank.java

import java.util.Scanner;
public class MainBank {
    private static Scanner scanner = new Scanner(System.in);
    private static Bank bank = new Bank("CityBank");
    public static void main(String[] args) {
        boolean quit = false;
        startBank();
        printActions();
        while (!quit) {
            System.out.println("------------------------------------");
            System.out.println("Enter number to action: ");
            int choice = scanner.nextInt();
            scanner.nextLine();
            switch (choice) {
                case 0:
                    quit = true;
                    System.out.println("Thank you, Good bye!");
                    break;
                case 1:
                    bank.printBranches();
                    break;
                case 2:
                    addNewBranch();
                    break;
                case 3:
                    addNewCustomer();
                    break;
                case 4:
                    transaction();
                    break;
                case 5:
                    printCustomer();
                    break;
                case 6:
                    printActions();
                    break;
            }
        }
    }
    private static void addNewBranch() {
        System.out.println("This function is addNewBranch");
        System.out.println("Enter new branch code: ");
        String branchName = scanner.nextLine();
        if (bank.addNewBranch(branchName)) {
            System.out.println("Successful! New branch code [" + branchName + "] be added to " + bank.getName());
        } else {
            System.out.println("Error! Cannot add branch code [" + branchName + "] to \" + bank.getName())");
            System.out.println("Branch code [" + branchName + "] already in " + bank.getName());
        }
        System.out.println("addNewBranch function out!");
    }
    private static void addNewCustomer() {
        System.out.println("This function is addNewCustomer");
        if (bank.printBranches()) {
            System.out.println("Which branch need to add new customer?\nEnter branch code: ");
            String branchName = scanner.nextLine();
            if (bank.queryBranch(branchName) != null) {
                System.out.println("Enter new customer name: ");
                String customerName = scanner.nextLine();
                System.out.println("How much initial amount do you want to set?");
                double initialAmount = scanner.nextDouble();
                scanner.nextLine();
                if (bank.addNewCustomer(branchName, customerName, initialAmount)) {
                    System.out.println("Successful! New customer: " + customerName + " be added  to branch code [" + branchName + "]");
                } else {
                    System.out.println("Error! Cannot add " + customerName + " to branch code [" + branchName + "].");
                    System.out.println("Customer already in that branch.");
                }
            } else {
                System.out.println("Error! Branch code [" + branchName + "] doesn't exist!");
            }
        }
        System.out.println("addNewCustomer function out!");
    }
    private static void transaction() {
        System.out.println("This function is transaction");
        if (bank.printBranches()) {
            System.out.println("A pay $amount to B");
            System.out.println("Enter customer A -> branch code: ");
            String branchA = scanner.nextLine();
            if (bank.queryBranch(branchA) != null) {
                Branch branch_A = bank.queryBranch(branchA);
                System.out.println("Enter customer A -> name: ");
                String customerA = scanner.nextLine();
                if (branch_A.queryCustomer(customerA) != null) {
                    Customer customer_A = branch_A.queryCustomer(customerA);
                    System.out.println("Pay how much?");
                    double amount = scanner.nextDouble();
                    scanner.nextLine();
                    if (customer_A.getBalance() >= amount) {
                        System.out.println("Enter customer B -> branch code: ");
                        String branchB = scanner.nextLine();
                        if (bank.queryBranch(branchB) != null) {
                            Branch branch_B = bank.queryBranch(branchB);
                            System.out.println("Enter customer B -> name: ");
                            String customerB = scanner.nextLine();
                            if (branch_B.queryCustomer(customerB) != null) {
                                if (bank.customersTransaction(branchA, customerA, branchB, customerB, amount)) {
                                    System.out.println("Successful!");
                                    System.out.println(customerA + " pay $" + amount + " to " + customerB);
                                } else {
                                    System.out.println("Error, transaction failed!");
                                }
                            } else {
                                System.out.println("Error! " + customerB + " doesn't exist in branch code [" + branchB + "]");
                            }
                        } else {
                            System.out.println("Error! Branch code [" + branchB + "] doesn't exist!");
                        }
                    } else {
                        System.out.println("Error! " + customerA + " balance isn't enough!");
                    }
                } else {
                    System.out.println("Error! " + customerA + " doesn't exist in branch code [" + branchA + "]");
                }
            } else {
                System.out.println("Error! Branch code [" + branchA + "] doesn't exist!");
            }
        }
        System.out.println("transaction function out!");
    }
    private static void printCustomer() {
        System.out.println("This function is printCustomer");
        if (bank.printBranches()) {
            System.out.println("Which branch need to print all customer?\nEnter branch code: ");
            String branchName = scanner.nextLine();
            if (bank.queryBranch(branchName) != null) {
                bank.printBranchCustomer(branchName);
            } else {
                System.out.println("Error! Branch code [" + branchName + "] doesn't exist!");
            }
        }
        System.out.println("printCustomer function out!");
    }
    private static void printActions() {
        System.out.println("\nAvailable actions:\nPress number of list.");
        System.out.println("0  - to shutdown\n" +
                "1  - to print branches\n" +
                "2  - to add a new branch\n" +
                "3  - to add a new customer\n" +
                "4  - to add a transaction\n" +
                "5  - to print customer list of branch\n" +
                "6  - to print action.");
    }
    private static void startBank() {
        System.out.println("Start Bank app ------");
    }
}

此為看完 Tim 的代碼，把最上方 我的代碼 進行修正

大部分都有照著單一功能，簡潔化的方向去修改

但是在 MainBank.java 的 Method transaction() 就弄得很醜

我一時間也不曉得要怎麼修改

等以後看更多案例學習吧

主程式運行方式：

運行 MainBank.java

功能會由 printActions() 直接提示出來

照著要使用的功能，輸入數字操作

0.關閉程序

1.顯示現有分行

2.增加分行

3.增加客戶及開戶金額到現有分行

4.轉帳（顧客A 轉帳給 顧客B）

5.顯示特定分行裡所有客戶名單跟交易過程

代碼邏輯：

功能寫在三個 Class 裡，分別為 Customer、Branch、Bank

主要就是用 Arraylist 紀錄創建的 Customer 跟 Branch 的資料

Bank 裡有 Branch 的資料，Branch 裡有 Customer 的資料

大致功能就是寫 新增 跟 查詢，參考前面的 MobilePhone project 即可

轉帳的寫法就是 先檢查 A 客戶要付的金額是否大於帳戶內餘額

若有的話就回傳失敗，沒有的話就進行轉帳

A 客戶 新增一筆 付款（負數）

B 客戶 新增一筆 收款

算餘額就用 for 把第一筆加到最後一筆就得出

要注意的是不要把餘額這個變量寫到全局

把變量寫在 Method 裡，調用的時候在算就好

我一開始寫到 Class 裡當全局變量用，結果調用 Method 的過程中數字重複計算

有時候跑出正確餘額，有時候跑出錯誤餘額，害我找問題找半天

改寫到 Method 裡才解決問題

本篇使用代碼