From cc8fc1843aca6ca991203a15b377aea32868eda4 Mon Sep 17 00:00:00 2001
From: johnA1331 <53036378+johnA1331@users.noreply.github.com>
Date: Thu, 20 May 2021 01:07:46 +0800
Subject: [PATCH] Update README.md

---
 core-java-modules/core-java-lang-oop-patterns/README.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/core-java-modules/core-java-lang-oop-patterns/README.md b/core-java-modules/core-java-lang-oop-patterns/README.md
index 178a556a96..df68a1413a 100644
--- a/core-java-modules/core-java-lang-oop-patterns/README.md
+++ b/core-java-modules/core-java-lang-oop-patterns/README.md
@@ -7,3 +7,4 @@ This module contains articles about Object-oriented programming (OOP) patterns i
 - [Inheritance and Composition (Is-a vs Has-a relationship) in Java](https://www.baeldung.com/java-inheritance-composition)
 - [Immutable Objects in Java](https://www.baeldung.com/java-immutable-object)
 - [How to Make a Deep Copy of an Object in Java](https://www.baeldung.com/java-deep-copy)
+- [Using an Interface vs. Abstract Class in Java](https://www.baeldung.com/java-interface-vs-abstract-class)