Adapter Design Pattern

The Adapter Design Pattern is a structural design pattern used to allow incompatible interfaces to work together. It acts as a bridge between two incompatible interfaces, helping legacy or third-party systems integrate smoothly without modifying existing code.

✅ Benefits in the Banking Domain

• 🧩 Interoperability: Easily integrate legacy or third-party systems with your existing banking architecture.

• 🛡️ Encapsulation: You don’t expose the legacy code or modify it directly.

• 🔄 Reusability: Allows reuse of old code without rewriting.

• 🚀 Scalability: Add new adapters as new services/systems are onboarded.
  
  

📝 Real-World Scenarios in Banking

🏦 Example in the Banking Domain

✅ Use Case: Integrating a Legacy Payment Gateway with a Modern Banking App

Imagine your banking application uses a standard interface called PaymentProcessor, but an old third-party system provides a class LegacyBankAPI that doesn't follow this interface.

💻 1. Target Interface (Expected by the banking app)

  public interface PaymentProcessor {
    void processPayment(String account, double amount);
}

🧱 2. Adaptee (Legacy System with a Different Interface)

public class LegacyBankAPI {
    public void makeTransaction(String accNo, double amt) {
        System.out.println("Payment of ₹" + amt + " done to account " + accNo + " via LegacyBankAPI");
    }
}

🔌 3. Adapter (Bridges LegacyBankAPI and PaymentProcessor)

public class LegacyBankAdapter implements PaymentProcessor {

    private LegacyBankAPI legacyAPI;

    public LegacyBankAdapter(LegacyBankAPI legacyAPI) {
        this.legacyAPI = legacyAPI;
    }

    @Override
    public void processPayment(String account, double amount) {
        // Adapting the call
        legacyAPI.makeTransaction(account, amount);
    }
}

🧪 4. Client Code (Modern banking app)

public class BankApp {
    public static void main(String[] args) {
        PaymentProcessor processor = new LegacyBankAdapter(new LegacyBankAPI());
        processor.processPayment("1234567890", 5000.00);
    }
}