Anyone could explain this code step by step? thanks in advance! importjava.util.Scanner;
	public class BankApplication {
	Scanner scan;
	Bank bank;
	private boolean shouldRunAgain = true;
	public static void main(String[] args) {
	BankApplication application = new BankApplication();
	application.runApplication();
	}
	public BankApplication() {
	// CONFIG - START
	scan = new Scanner(System.in);
	// Should be using this according to FAQ
	scan.useDelimiter(System.lineSeparator());
	// CONFIG - END
	bank = new Bank();
	}
	/**
	* Wrapper for running application(menu and what comes after it)
	*/
	private void runApplication() {
	int menuChoice;
	int accountNr;
	String input;
	double amount;
	do {
	printMenu();
	printAction("val");
	menuChoice = scan.nextInt();
	switch (menuChoice) {
	case 1:
	printAction("id");
	long id = scan.nextLong();
	System.out.println(handleFindAccountFromOwner(id));
	break;
	case 2:
	printAction("namn");
	input = scan.next();
	System.out.println(handleSearchAccountOwnerFromPartOfName(input));
	break;
	case 3:
	printAction("konto");
	accountNr = scan.nextInt();
	printAction("belopp");
	amount = scan.nextDouble();
	try {
	System.out.println(handleDepositMoney(accountNr, amount));
	} catch (IllegalArgumentException e) {
	System.out.println("Beloppet mste vara positivt. ");
	} catch (NullPointerException e) {
	System.out.println("Var snll ange ett konto som finns");
	}
	break;
	case 4:
	printAction("frn konto");
	accountNr = scan.nextInt();
	printAction("belopp");
	amount = scan.nextDouble();
	try {
	System.out.println(handleWithdrawMoney(accountNr, amount));
	} catch (IllegalArgumentException e) {
	System.out.println(e.getMessage());
	}
	break;
	case 5:
	printAction("frn konto");
	int fromAccountId = scan.nextInt();
	printAction("till konto");
	int toAccountId = scan.nextInt();
	printAction("belopp");
	amount = scan.nextDouble();
	try {
	System.out.println(handleTransfer(fromAccountId, toAccountId, amount));
	} catch (IllegalArgumentException e) {
	System.out.println(e.getMessage());
	}
	break;
	case 6:
	printAction("namn");
	String name = scan.next();
	printAction("id");
	id = scan.nextLong();
	System.out.println(handleCreateAccount(name, id));
	break;
	case 7:
	printAction("konto");
	accountNr = scan.nextInt();
	handleRemoveAccount(accountNr);
	break;
	case 8:
	System.out.println(handlePrintAllAccounts());
	break;
	case 9:
	handleCloseApplication();
	break;
	default:
	System.out.println("Skriv ett tal mellan 0 till 9");
	break;
	}
	}
	// This should run again and again until user closes it.
	while (shouldRunAgain);
	}
	private String handleFindAccountFromOwner(long id) {
	StringBuilder returnString = new StringBuilder();
	for (BankAccount account : bank.findAccountsForHolder(id)) {
	returnString.append(account + " ");
	}
	return returnString.toString();
	}
	private String handleSearchAccountOwnerFromPartOfName(String name) {
	StringBuilder returnString = new StringBuilder();
	for (Customer customer : bank.findByPartofName(name)) {
	returnString.append(customer + " ");
	}
	return returnString.toString();
	}
	private double handleDepositMoney(int accountNr, double amount) {
	// Search for the account and then deposit the money
	BankAccount account = bank.findByNumber(accountNr);
	account.deposit(amount);
	return amount;
	}
	private BankAccount handleWithdrawMoney(int accountNr, double amount) {
	// Search for the account and then deposit the money
	BankAccount account = bank.findByNumber(accountNr);
	// If the account is null, then we cannot withdraw
	if (account == null) {
	throw new IllegalArgumentException("Accountnr not valid: " + accountNr);
	}
	account.withdraw(amount);
	return account;
	}
	private String handleTransfer(int fromAccountId, int toAccountId, double amount) {
	StringBuilder returnString = new StringBuilder();
	// Here we transfer the money, it is removed from sender and added to
	// reciever.
	BankAccount fromAccount = bank.findByNumber(fromAccountId);
	if (fromAccount == null) {
	throw new IllegalArgumentException("Sending account is not valid: " + fromAccountId);
	}
	BankAccount toAccount = bank.findByNumber(toAccountId);
	if (toAccount == null) {
	throw new IllegalArgumentException("Recieveing account is not valid: " + toAccountId);
	}
	fromAccount.withdraw(amount);
	toAccount.deposit(amount);
	returnString.append(fromAccount.toString() + " ");
	returnString.append(toAccount.toString() + " ");
	return returnString.toString();
	}
	private String handleCreateAccount(String name, long id) {
	int accountId = bank.addAccount(name, id);
	return "konto skapat: " + accountId;
	}
	private void handleRemoveAccount(int accountNr) {
	bank.removeAccount(accountNr);
	}
	private String handlePrintAllAccounts() {
	StringBuilder returnString = new StringBuilder();
	for (BankAccount account : bank.getAllAccounts()) {
	returnString.append(account.toString() + " ");
	}
	return returnString.toString();
	}
	private void handleCloseApplication() {
	// When setting this to false, the while loop run runApplication() will
	// not run again.
	shouldRunAgain = false;
	}
	private void printMenu() {
	System.out.println("------------------ ");
	System.out.println("1. Hitta konto utifrn innehavare" + " 2. Sk kontoinnehavare utifrn (del av) namn"
	+ " 3. Stt in" + " 4. Ta ut" + " 5. verfring" + " 6. Skapa konto" + " 7. Ta bort konto"
	+ " 8. Skriv ut konton" + " 9. Avsluta");
	}
	/**
	* Prints the action that the user should type in. E.g. if name needs to be
	* sent in, run printAction("name") The colon will automatically be
	* inserted.
	*
	* @param action
	*/
	private void printAction(String action) {
	System.out.println(action + ": ");
	}
	}