Interface vs Abstract Class in Java (Complete Deep Dive) | Interview Prep

What is the real difference between an Interface and an Abstract Class in Java—especially after Java 8 and Java 9 added default, static, and private methods to Interfaces? In this complete Core Java masterclass, we break down the architectural difference (IS-A vs. CAN-DO), write a real-world Stripe Payment Processor in Eclipse, and cover 6 of the trickiest interview questions and compiler traps! 💻 Source Code on GitHub: https://github.com/bearStack-beer/Jav... 📌 Topics & Interview Questions Covered: ✅ 1. When to use an Abstract Class (IS-A & Shared State) vs. an Interface (CAN-DO Contract) ✅ 2. Can an Abstract Class have a Constructor? (How super() constructor chaining works) ✅ 3. Why Interface variables are implicitly public static final (Constants Trap) ✅ 4. Why Interface methods are implicitly public (Visibility Reduction Compile Error) ✅ 5. Why Java 8 introduced default and static methods in Interfaces (Backward Compatibility) ✅ 6. How to solve the Java 8 Diamond Problem (InterfaceName.super.methodName()) ✅ 7. Can an Abstract Class have ZERO abstract methods? Can it be marked final? 🔔 Subscribe to BearStack for more Core Java tutorials, coding interview prep, and backend engineering breakdowns! #Java #CoreJava #JavaInterviewQuestions #InterfaceVsAbstractClass #ObjectOrientedProgramming #Java8 #CodingInterview #LearnJava #SoftwareEngineering #BearStack