BankAccount.java

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * 🏦 Banka Hesap Yönetimi
 * Kavramlar: OOP, Encapsulation, ArrayList, Exception Handling
 */

// İşlem kaydı
class Transaction {
    private String type;
    private double amount;
    private double balance;
    private Date date;

    public Transaction(String type, double amount, double balance) {
        this.type = type;
        this.amount = amount;
        this.balance = balance;
        this.date = new Date();
    }

    @Override
    public String toString() {
        return String.format("[%s] %s: %.2f TL | Bakiye: %.2f TL", date, type, amount, balance);
    }
}

// Banka hesabı
class BankAccount {
    private String owner;
    private String accountNumber;
    private double balance;
    private List<Transaction> transactions;

    public BankAccount(String owner, String accountNumber, double initialBalance) {
        this.owner = owner;
        this.accountNumber = accountNumber;
        this.balance = initialBalance;
        this.transactions = new ArrayList<>();
        transactions.add(new Transaction("AÇILIŞ", initialBalance, balance));
    }

    public void deposit(double amount) {
        if (amount <= 0) throw new IllegalArgumentException("Yatırma miktarı 0'dan büyük olmalıdır!");
        balance += amount;
        transactions.add(new Transaction("YATIRIM", amount, balance));
        System.out.printf("✅ %.2f TL yatırıldı. Yeni bakiye: %.2f TL%n", amount, balance);
    }

    public void withdraw(double amount) {
        if (amount <= 0) throw new IllegalArgumentException("Çekme miktarı 0'dan büyük olmalıdır!");
        if (amount > balance) throw new IllegalStateException("Yetersiz bakiye!");
        balance -= amount;
        transactions.add(new Transaction("ÇEKİM", amount, balance));
        System.out.printf("✅ %.2f TL çekildi. Yeni bakiye: %.2f TL%n", amount, balance);
    }

    public void transfer(BankAccount target, double amount) {
        this.withdraw(amount);
        target.deposit(amount);
        System.out.printf("✅ %s → %s transferi tamamlandı.%n", this.owner, target.owner);
    }

    public void printStatement() {
        System.out.println("\n========== HESAP EKSTRESİ ==========");
        System.out.printf("Hesap Sahibi : %s%n", owner);
        System.out.printf("Hesap No     : %s%n", accountNumber);
        System.out.printf("Güncel Bakiye: %.2f TL%n", balance);
        System.out.println("--- İşlem Geçmişi ---");
        transactions.forEach(System.out::println);
        System.out.println("=====================================\n");
    }

    public double getBalance() { return balance; }
    public String getOwner()   { return owner; }
}

public class BankAccount {
    public static void main(String[] args) {
        BankAccount bengu = new BankAccount("Bengü Gedik", "TR001", 1000.0);
        BankAccount ahmet = new BankAccount("Ahmet Yılmaz", "TR002", 500.0);

        bengu.deposit(2000);
        bengu.withdraw(500);
        bengu.transfer(ahmet, 300);

        bengu.printStatement();
        ahmet.printStatement();

        // Exception handling testi
        try {
            bengu.withdraw(99999);
        } catch (IllegalStateException e) {
            System.out.println("❌ Hata: " + e.getMessage());
        }
    }
}