Account.java

import java.io.Serializable;
import java.util.*;

public abstract class Account implements Serializable {

    protected String accountNumber;
    protected double balance;
    protected List<Transaction> transactions;

    public Account() {
        this.accountNumber = UUID.randomUUID().toString();
        this.balance = 0.0;
        this.transactions = new ArrayList<>();
    }

    public String getAccountNumber() {
        return accountNumber;
    }

    public boolean deposit(double amount) {

        if (amount <= 0) {
            System.out.println("Invalid deposit amount.");
            return false;
        }

        balance += amount;
        transactions.add(new Transaction(TransactionType.DEPOSIT, amount));

        System.out.println("Deposit successful.");
        return true;
    }

    public boolean withdraw(double amount) {

        if (amount <= 0) {
            System.out.println("Invalid withdrawal amount.");
            return false;
        }

        if (amount > balance) {
            System.out.println("Insufficient balance.");
            return false;
        }

        balance -= amount;
        transactions.add(new Transaction(TransactionType.WITHDRAW, amount));

        System.out.println("Withdrawal successful.");
        return true;
    }

    public double getBalance() {
        return balance;
    }

    public void printStatement() {
        if (transactions.isEmpty()) {
            System.out.println("No transactions available.");
            return;
        }

        for (Transaction t : transactions) {
            System.out.println(t);
        }
    }
}