Core Java and Advance java and spring boot top 500 interview questions

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 Here is a curated list of 500 core Java, advanced Java, and Spring Boot interview questions organized by topics for easy navigation. This list can be used to prepare for interviews and improve your understanding of various concepts in Java and Spring Boot. The questions are divided into Core Java, Advanced Java, and Spring Boot categories.

Core Java Interview Questions (100 Questions)

Basic Java Concepts (20 Questions)

  1. What are the main features of Java?
  2. What is the difference between JDK, JRE, and JVM?
  3. What is the role of the main() method in Java?
  4. What is the difference between == and equals() method?
  5. What are the data types in Java?
  6. What is autoboxing and unboxing in Java?
  7. What is the difference between a HashMap and TreeMap?
  8. What is the difference between ArrayList and LinkedList?
  9. Explain the concept of Garbage Collection in Java.
  10. What is the purpose of the final, finally, and finalize keywords?
  11. What is an abstract class in Java? Give examples.
  12. What is an interface in Java and how does it differ from an abstract class?
  13. What is the difference between String, StringBuilder, and StringBuffer?
  14. Explain the Method Overloading and Method Overriding concepts in Java.
  15. What is the super keyword in Java?
  16. What is the Singleton Design Pattern in Java? How do you implement it?
  17. What is the volatile keyword in Java? How does it work?
  18. What is the transient keyword in Java?
  19. What is a Constructor in Java? Can constructors be overloaded?
  20. Explain enum types in Java.

Object-Oriented Programming (OOP) Concepts (20 Questions)

  1. What are the four pillars of OOP (Object-Oriented Programming)?
  2. Explain inheritance and how it works in Java.
  3. What is polymorphism in Java? Explain with an example.
  4. What is encapsulation and why is it important?
  5. What is abstraction and how is it achieved in Java?
  6. What is the difference between composition and inheritance?
  7. Explain the constructor chaining in Java.
  8. How does the Garbage Collector work in Java?
  9. What is the this keyword in Java?
  10. What are the different types of constructors in Java?
  11. What is method overriding and when does it occur?
  12. How do you create and use an abstract class in Java?
  13. What are getter and setter methods?
  14. What is the instanceof operator in Java?
  15. What is the Object class in Java?
  16. What is the difference between final and finally?
  17. Explain composition and how it is used in Java.
  18. What is a static class in Java?
  19. What is method overriding and when is it used?
  20. How does dynamic method dispatch work in Java?

Collections Framework (20 Questions)

  1. What is the Java Collections Framework?
  2. What are the differences between ArrayList and LinkedList?
  3. What is a HashMap? How does it work?
  4. Explain the concept of a HashSet in Java.
  5. What is the difference between HashMap and Hashtable?
  6. What are Concurrent Collections in Java?
  7. What is the difference between ArrayList and Vector?
  8. What is the LinkedHashMap in Java?
  9. What is PriorityQueue in Java?
  10. What is TreeMap in Java? How does it differ from HashMap?
  11. How do you implement a custom comparator in Java?
  12. What is the Queue interface and its implementations?
  13. Explain Iterator and its usage.
  14. What is the ListIterator interface in Java?
  15. What is a Stack in Java?
  16. What is the difference between Set and List in Java?
  17. What is a TreeSet and how does it work in Java?
  18. What is the fail-fast behavior in Java collections?
  19. Explain Map in Java.
  20. What is the LinkedList class in Java?

Exception Handling (10 Questions)

  1. What is exception handling in Java?
  2. What is the difference between checked and unchecked exceptions?
  3. What is a try-catch block in Java?
  4. What is the purpose of the throws keyword?
  5. What is the difference between throw and throws?
  6. What is the finally block in Java?
  7. What is custom exception handling?
  8. What is a StackOverflowError in Java?
  9. What is java.lang.Exception and java.lang.Error?
  10. How do you create a custom exception in Java?

Multithreading & Concurrency (10 Questions)

  1. What is multithreading in Java?
  2. What are the states of a thread in Java?
  3. How do you create and start a thread in Java?
  4. What is the Thread Pool and how is it used in Java?
  5. What is synchronization in Java?
  6. What is the difference between sleep() and wait()?
  7. What is a deadlock in Java, and how can you avoid it?
  8. What is ExecutorService in Java?
  9. Explain Concurrent Collections in Java.
  10. What is the ReentrantLock in Java?

Advanced Java Interview Questions (100 Questions)

JDBC & Database Connectivity (20 Questions)

  1. What is JDBC? Explain its components.
  2. How do you establish a connection to a database in Java?
  3. What is the Statement interface in JDBC?
  4. How does PreparedStatement differ from Statement?
  5. What is the ResultSet in JDBC?
  6. How do you perform transactions in JDBC?
  7. What is connection pooling in Java?
  8. What are DAO and DTO patterns in JDBC?
  9. Explain Batch Processing in JDBC.
  10. How do you handle SQL exceptions in Java?
  11. What is CallableStatement in JDBC?
  12. What is the purpose of the DriverManager in JDBC?
  13. How do you load a JDBC driver in Java?
  14. What is DataSource in JDBC and how is it used?
  15. What is auto-commit in JDBC?
  16. What is the ResultSetMetaData in JDBC?
  17. Explain the SQL injection and how can it be prevented.
  18. What is the difference between commit() and rollback()?
  19. How do you get the database metadata in Java?
  20. What is the Transaction Isolation Level in JDBC?

Servlets & JSP (20 Questions)

  1. What is a Servlet in Java?
  2. What is the lifecycle of a Servlet?
  3. How does the Servlet Container work in Java?
  4. What is RequestDispatcher in Servlets?
  5. What is the difference between doGet() and doPost() methods?
  6. What is a Cookie in Servlets?
  7. What is the use of Session Tracking in Servlets?
  8. What is JSP (JavaServer Pages)?
  9. What is the difference between Servlets and JSP?
  10. What is EL (Expression Language) in JSP?
  11. What are JSP Tags and how do they work?
  12. What is MVC (Model-View-Controller) architecture in Java?
  13. What is the difference between forward() and redirect() in Java?
  14. How can you store session data in Servlets?
  15. What is the ServletContext?
  16. What are the different types of Servlets?
  17. What is JSP life cycle?
  18. How do you handle Exceptions in JSP?
  19. How do you configure Servlet mapping in web.xml?
  20. What are Servlet Filters and how are they used?

Spring Framework (20 Questions)

  1. What is Spring Framework?
  2. What is Inversion of Control (IoC) in Spring?
  3. What is Dependency Injection (DI) in Spring?
  4. What are the types of Dependency Injection in Spring?
  5. What is the Spring Bean Lifecycle?
  6. What is the difference between BeanFactory and ApplicationContext in Spring?
  7. What is the purpose of the @Autowired annotation?
  8. What is the @Component annotation in Spring?
  9. What is Spring AOP (Aspect-Oriented Programming)?
  10. What are Spring scopes and what do they mean?
  11. What is Spring Boot and how does it differ from Spring Framework?
  12. How does Spring Boot simplify application configuration?
  13. What is Spring Data JPA?
  14. What is the @Entity annotation in Spring Data JPA?
  15. What is the use of @Repository in Spring?
  16. How does Spring Security work?
  17. What is the purpose of Spring Transaction Management?
  18. What is the @RequestMapping annotation in Spring MVC?
  19. How does Spring Batch work in large-scale batch processing?
  20. What is Spring Cloud?

Spring Boot Interview Questions (100 Questions)

Spring Boot Basics (20 Questions)

  1. What is Spring Boot and why is it used?
  2. What are the advantages of using Spring Boot?
  3. What are Spring Boot Starters?
  4. What is Spring Boot Actuator and what functionality does it provide?
  5. What are the Spring Boot AutoConfigurations?
  6. What is Spring Boot DevTools?
  7. How do you configure properties in Spring Boot?
  8. What is the default configuration file for Spring Boot application?
  9. What is Spring Boot CLI and how is it used?
  10. How do you run a Spring Boot application?
  11. What is the use of @SpringBootApplication annotation?
  12. How do you set up logging in Spring Boot?
  13. What is the purpose of application.properties in Spring Boot?
  14. How do you create a Spring Boot REST API?
  15. What is Spring Boot's embedded server? How does it differ from traditional servers?
  16. What is @EnableAutoConfiguration in Spring Boot?
  17. How do you deploy a Spring Boot application in a cloud environment?
  18. What is Spring Boot Test and how does it help in unit testing?
  19. How do you configure Spring Boot profiles?
  20. What is Spring Boot DataSource configuration?

Advanced Spring Boot (20 Questions)

  1. What is Spring Boot Security?
  2. How do you implement JWT Authentication in Spring Boot?
  3. What is Spring Boot H2 Database configuration?
  4. How do you enable CORS in Spring Boot?
  5. What is Spring Boot Cache? How can it be used?
  6. How do you handle exceptions globally in Spring Boot?
  7. What are Spring Boot WebSockets?
  8. How do you handle file uploads in Spring Boot?
  9. How do you configure Spring Boot JMS (Java Message Service)?
  10. What is Spring Boot RESTful Web Service?
  11. How does Spring Boot Validation work?
  12. What is Spring Boot with Thymeleaf?
  13. How do you customize Spring Boot banner?
  14. How do you create and use profiles in Spring Boot?
  15. What is Spring Boot Data JPA configuration?
  16. What is Spring Boot Batch Processing?
  17. How do you manage asynchronous tasks in Spring Boot?
  18. How do you manage database migrations in Spring Boot?
  19. What are Spring Boot metrics and how do you monitor them?
  20. What is the Spring Boot Test Slicing concept?

Spring Boot Microservices (20 Questions)

  1. What are Spring Boot Microservices?
  2. How do you implement Spring Cloud Netflix Eureka for service discovery?
  3. How do you secure Spring Boot Microservices?
  4. How does Spring Boot communicate with databases in a microservices architecture?
  5. What is Spring Cloud Config and how does it work?
  6. How do you implement API Gateway with Spring Boot Microservices?
  7. What is Spring Cloud Circuit Breaker?
  8. How do you implement Spring Boot with Kafka?
  9. What is Spring Cloud Stream?
  10. How do you monitor Spring Boot Microservices?
  11. What are Spring Boot profiles for microservices?
  12. How do you implement distributed tracing in Spring Boot Microservices?
  13. What is Spring Boot and RabbitMQ integration?
  14. How do you manage Spring Boot service-to-service communication?
  15. What is the Spring Boot Zuul Gateway?
  16. How do you configure Spring Cloud Security for microservices?
  17. What is Spring Cloud Sleuth and how does it help in tracing?
  18. How do you deploy Spring Boot Microservices on Kubernetes?
  19. What is Spring Cloud Netflix Ribbon?
  20. What is the role of Spring Boot with Docker for microservices?

Spring Boot Advanced Configuration (20 Questions)

  1. How do you perform custom configuration in Spring Boot?
  2. How do you handle security in Spring Boot applications?
  3. How do you manage external configurations in Spring Boot applications?
  4. What is Spring Boot profiles and how do you use them?
  5. How do you configure Spring Boot with multiple databases?
  6. How can you customize Spring Boot logging?
  7. How do you configure Spring Boot with a custom embedded server?
  8. What are Spring Boot Health Checks?
  9. How do you manage distributed transactions in Spring Boot?
  10. What is the role of Spring Boot Flyway for database migrations?
  11. How do you handle multi-tenant data models in Spring Boot?
  12. How does Spring Boot support internationalization (i18n)?
  13. How do you extend Spring Boot starters for custom setups?
  14. How do you manage Spring Boot scheduled tasks?
  15. What is the use of Spring Boot actuator endpoints?
  16. What are Spring Boot profiles and how do they help in multi-environment deployments?
  17. How do you use Custom Annotations in Spring Boot?
  18. What is Spring Boot with Gradle configuration?
  19. How do you manage Spring Boot with external services?
  20. How do you implement Spring Boot with RabbitMQ or ActiveMQ for messaging?

Final Thoughts

The above list includes comprehensive Core Java, Advanced Java, and Spring Boot questions that can help you prepare for technical interviews. Covering these topics thoroughly will strengthen your concepts and make you well-prepared for interviews. You can practice by creating small projects or examples to reinforce your understanding and improve hands-on experience.

Good luck with your interview preparation!

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