BankApp.java

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Scanner;

public class BankApp {

  static HashMap<String, Customer> customerMap = new HashMap<String, Customer>(); 
  static Customer existingCustomer;
  static Scanner in = new Scanner(System.in);

  static String getMainMenu() {
    String menuChoice;

    System.out.println("\n\n-----------*************-----------");
    System.out.println("Choose an option:");
    System.out.println("1. Add New Customer");
    System.out.println("2. Search Existing Customer");
    System.out.println("3. Exit");
    System.out.println("-----------*************-----------\n\n");
    System.out.print("Enter your choice: ");
    menuChoice = in.next();
    return menuChoice;
  }

  static Customer register() {
    String id;
    String name;
    String gender;
    String location;
    int accountType;
    int accountNo;
    
    System.out.println("-----------*************-----------");
    System.out.print("Enter ID No.: ");
    id = in.next();
    System.out.print("Enter Name: ");
    name = in.next();
    System.out.print("Enter Gender(M/F): ");
    gender = in.next();
    System.out.print("Enter Location: ");
    location = in.next();
    System.out.print("Enter A/C Type(0 = Savings, 1 = Current): ");
    accountType = in.nextInt();
    System.out.print("Enter A/C No: ");
    accountNo = in.nextInt();
    System.out.println("-----------*************-----------");

    return new Customer(id, name, gender, location, accountType, accountNo);
  }

  static void findCustomer() {
    System.out.println("-----------*************-----------");
    System.out.print("Enter Customer ID: ");
    String customerID = in.next();
    BankApp.existingCustomer = BankApp.customerMap.get(customerID);
    if (existingCustomer != null) {
      String existingCustomerMenuChoice = BankApp.existingCustomerMenu();
      existingCustomerChoiceSelector(existingCustomerMenuChoice);
      BankApp.mainChoiceSelector(BankApp.getMainMenu());
    } else {
      System.out.println("No Customer Found!!");
      BankApp.mainChoiceSelector(BankApp.getMainMenu());
    }
  }

  static void mainChoiceSelector(String mainMenuChoice) {
    switch(mainMenuChoice) {
      case "1":
        Customer newCustomer = BankApp.register();
        BankApp.customerMap.put(newCustomer.id, newCustomer);
        BankApp.mainChoiceSelector(BankApp.getMainMenu());
        break;
      case "2":
        BankApp.findCustomer();
        break;
      case "3":
        System.exit(0);
        break; 
      default:
        break;  
    }
  }
  
  static String existingCustomerMenu() {
    String menuChoice;

    System.out.println("\n");
    System.out.println("Choose an option:");
    System.out.println("1. Debit");
    System.out.println("2. Credit");
    System.out.println("3. Account Summary");
    System.out.println("3. Edit Customer");
    System.out.println("4. Delete Customer");
    System.out.println("5. Back to Main Menu");
    System.out.println("6. Exit");
    System.out.println("-----------*************-----------\n\n");
    System.out.print("Enter your choice: ");
    menuChoice = in.next();
    return menuChoice;
  }

  static void existingCustomerChoiceSelector(String existingCustomerMenuChoice) {
    switch (existingCustomerMenuChoice) {
      case "1":
        BankApp.customerDebit();
        existingCustomerChoiceSelector(BankApp.existingCustomerMenu());
        break;
      case "2":
        BankApp.customerCredit();
        existingCustomerChoiceSelector(BankApp.existingCustomerMenu());
        break;
      case "3":
        BankApp.customerAccountSummary();
        existingCustomerChoiceSelector(BankApp.existingCustomerMenu());   
        break;
      case "5":
        BankApp.mainChoiceSelector(BankApp.getMainMenu());   
        break;
      case "6":
        System.exit(0);  
        break;
      default:
      break;
    }
  }

  static void customerDebit() {
    System.out.print("Enter amount to be debited: ");
    Double amount = in.nextDouble();
    existingCustomer.debit(amount);
    System.out.println("Amount debited successfully.");
    System.out.println("-----------*************-----------");
  }

  static void customerCredit() {
    System.out.print("Enter amount to be credited: ");
    Double amount = in.nextDouble();
    existingCustomer.credit(amount);
    System.out.println("Amount credited successfully.");
    System.out.println("-----------*************-----------");
  }

  static void customerAccountSummary() {
    existingCustomer.accountSummary();
  }
  public static void main(String ...args) {
    BankApp.mainChoiceSelector(BankApp.getMainMenu());
  }
}

class Customer {

  String id;
  String name;
  String gender;
  String location;
  int accountType;
  int accountNo;
  ArrayList<AccountBookeeping> book;

  Customer(String id, String name, String gender, String location, int accountType, int accountNo) {
    this.id = id;
    this.name = name;
    this.gender = gender;
    this.location = location;
    this.accountType = accountType;
    this.accountNo = accountNo;
    this.book = new ArrayList<AccountBookeeping>();
  }

  public void print() {
    System.out.println("-----------*************-----------");
    System.out.println("ID: \t" + this.id);
    System.out.println("Name: \t" + this.name);
    System.out.println("Gender: \t" + this.gender);
    System.out.println("Location: \t" + this.location);
    System.out.format("A/C Type: \t%d\n", this.accountType);
    System.out.format("A/C No.: \t%d\n", this.accountNo);
    System.out.println("-----------*************-----------");
  }

  private static String createDate() {
    String pattern = "dd/MM/yyyy HH:mm:ss";
    DateFormat df = new SimpleDateFormat(pattern);
    Date today = Calendar.getInstance().getTime();
    String todayAsString = df.format(today);
    return todayAsString;
  }

  private Double latestBalance() {
    if (!this.book.isEmpty()) {
      AccountBookeeping lastRecord = this.book.get(this.book.size() - 1);
      return lastRecord.balance;
    } else {
      return 0.0;
    }
  }

  public void debit(Double amount) {
    if (latestBalance() - amount >= 0) {
      this.book.add(new AccountBookeeping(createDate(), amount, 0.0, latestBalance() - amount));
    } else {
      System.out.println("Insufficient Balance!!");
    }
    
  }

  public void credit(Double amount) {
    this.book.add(new AccountBookeeping(createDate(), 0.0, amount, latestBalance() + amount));
  }

  public void accountSummary() {
    Iterator<AccountBookeeping> bookIterator = this.book.iterator();
    System.out.println("-----------*************-----------");
    System.out.printf("%-20.20s %-10.10s %-10.10s %-10.10s\n", "Date", "Debit", "Credit", "Balance");
    while (bookIterator.hasNext()) {
      AccountBookeeping record = bookIterator.next();
      System.out.printf("%-20.20s %-10.2f %-10.2f %-10.2f\n", record.date, record.debit, record.credit, record.balance);
    }
    System.out.println("-----------*************-----------");
  }
}

class AccountBookeeping {

  String date;
  Double debit;
  Double credit;
  Double balance;

  AccountBookeeping(String date, Double debit, Double credit, Double balance) {
    this.date = date;
    this.debit = debit;
    this.credit = credit;
    this.balance = balance;
  }
}