Java Interview Preparation
Design Patterns Interview Questions
Common Java design patterns, their trade-offs, and practical object-oriented use cases.
Design Patterns Interview Focus
Common Java design patterns, their trade-offs, and practical object-oriented use cases.
Interview questions
1. What is a design pattern, and why is it used in software development? Beginner
2. What are the three main categories of design patterns? Beginner
3. What is the difference between creational, structural, and behavioral design patterns? Beginner
4. What is the Singleton design pattern, and how can it be implemented in Java? Intermediate
5. How can you make a Singleton class thread-safe? Advanced
6. Why is an enum considered a good way to implement Singleton in Java? Intermediate
7. What is the Factory Method design pattern? Intermediate
8. What is the difference between Factory Method and Abstract Factory patterns? Advanced
9. What is the Builder design pattern, and when should it be used? Beginner
10. What is the difference between Builder and Factory design patterns? Intermediate
11. What is the Prototype design pattern, and how does cloning work in Java? Intermediate
12. What is the Adapter design pattern, and when would you use it? Beginner
13. What is the difference between Adapter, Facade, and Proxy patterns? Advanced
14. What is the Decorator design pattern, and how is it different from inheritance? Intermediate
15. What is the Observer design pattern, and where is it used in real applications? Beginner
16. What is the Strategy design pattern, and how does it help replace conditional logic? Intermediate
17. What is the difference between Strategy and State design patterns? Advanced
18. What is the Template Method design pattern? Intermediate
19. What is the Chain of Responsibility design pattern, and where is it useful? Intermediate
20. Which design patterns are commonly used in Spring and Spring Boot applications? Advanced
How to Prepare for Java Technical Interviews
Use this Java technical interview question bank to revise core concepts and practise explaining your decisions clearly. The questions cover Java fundamentals, object-oriented programming, collections, exceptions, multithreading, Spring Boot, Hibernate, databases, and other topics used in real software development interviews.
Start with the fundamentals, then move to scenario-based questions and advanced topics. Filter questions by difficulty to build confidence gradually. A strong answer should define the concept, explain why it matters, and include a practical example when appropriate.
Continue your preparation with the Java tutorials, or explore all interview preparation tracks for managerial and company-focused questions.