public class BankDatabase
{
    private Account[] accounts;     // array of Accounts

    // no-argument BankDatabase constructor initializes accounts
    public BankDatabase(){
        accounts = new Account[2];      // just 2 accounts for testing
        accounts[0] = new Account(12345, 54321, 1000.0, 1200.0);
        accounts[1] = new Account(98765, 56789, 200.0, 200.0);
    }   // end no-argument BankDatabase constructor

    // retrieve Account object containing specified account number
    private Account getAccount(int accountNumber){
        // loop through accounts searching for matching account number
        for(Account currentAccount : accounts){
            // return current account if match found
            if(currentAccount.getAccountNumber() == accountNumber) return currentAccount;
        }   // end for

        return null;    // if no matching account was found, return null
    }   // end method

    // determine whether user-specified account number and PIN match
    // those of an account in the database
    public boolean authenticateUser(int userAccountNumber, int userPIN){
        // attempt to retrieve the account with the account number
        Account userAccount = getAccount(userAccountNumber);

        if(userAccount != null){
            return userAccount.validatePIN(userPIN);
        }
        else{
            return false;   // account number not found, so return false
        }
    }   // end method

    // return available balance of Account with specified account number
    public double getAvailableBalance(int userAccountNumber){
        return getAccount(userAccountNumber).getAvailableBalance();
    }   // end method

    public double getTotalBalance(int userAccountNumber){
        return getAccount(userAccountNumber).getTotalBalance();
    }   // end method

    public void credit(int userAccountNumber, double amount){
        getAccount(userAccountNumber).credit(amount);
    }   // end method

    public void debit(int userAccountNumber, double amount){
        getAccount(userAccountNumber).debit(amount);
    }   // end method
}   // end class BankDatabase