Sync Adapter to Java 25: add StripePaymentClassAdapter, README mapping

README.md

@@ -178,6 +178,25 @@ javac 01-creational/singleton/*.java -d out/singleton
 java -cp out/singleton singleton.Main
 ```
 
+### Adapter (`02-structural/adapter/`)
+
+| Post Section | File(s) |
+|---|---|
+| Step 1 — Define the Target Interface | `PaymentGateway.java` |
+| Step 2 — The Adaptee (What You're Wrapping) | `StripeClient.java` |
+| Step 3 — The Object Adapter | `StripePaymentAdapter.java` |
+| Step 4 — The Client (Knows Nothing About Stripe) | `OrderService.java` |
+| Putting It Together: The Main Demo | `Main.java` |
+| Object Adapter vs Class Adapter | `StripePaymentClassAdapter.java` |
+
+Note: the `InputStreamReader` JDK-adapter snippet is illustrative only — it is not part of this repository's runnable example.
+
+Run it:
+```bash
+javac 02-structural/adapter/*.java -d out/adapter
+java -cp out/adapter adapter.Main
+```
+
 ## Reference
 
 - *Design Patterns: Elements of Reusable Object-Oriented Software* — Gamma, Helm, Johnson, Vlissides