Java and Spring Fundamentals Assessment

This interview assesses your foundational knowledge of core Java concepts and the Spring framework, crucial for a backend Java/Spring Software Engineer role. You will be asked a series of conceptual questions designed to evaluate your understanding across various domains.

1. Collections & Data Structures

• Compare ArrayList and LinkedList in Java, covering their internal implementation, time complexity for common operations (access, insertion, deletion), and typical use cases.

2. Object-Oriented Design

• Explain the SOLID design principles and provide a concise example for each.

3. Hash-based Collections & Concurrency

• Compare Hashtable and HashSet, detailing what each stores, how keys/values are handled, and their thread safety characteristics.
• Explain ConcurrentHashMap, how it differs from HashMap and Hashtable, and identify situations where its use is appropriate.

4. Strings and Immutability

• Compare String, StringBuilder, and StringBuffer in Java, including their mutability, thread safety, and appropriate use cases.
• Define object immutability, explain its benefits, and describe how to design and implement an immutable class in Java.

5. Concurrency Primitives

• Explain the purpose, behavior, problem-solving capabilities, and limitations of the volatile keyword in Java.
• Explain the synchronized keyword in Java, how it provides thread safety, and its associated trade-offs.
• Describe the java.util.concurrent.atomic package, the problem it solves, and the conceptual workings of classes like AtomicInteger and AtomicReference.

6. Exception Handling

• Discuss best practices for exception handling in Java, explaining the distinction between checked and unchecked exceptions.

7. Spring Core Concepts

• Explain Inversion of Control (IoC) and Dependency Injection (DI) within the Spring framework, providing an example of dependency wiring.
• Explain Aspect-Oriented Programming (AOP) in Spring and list common use cases (e.g., logging, transactions).
• Describe how to define, create, manage, and inject beans in Spring using various methods (e.g., annotations, Java configuration, or XML).
• Compare the stereotype annotations @Component, @Service, and @Repository in Spring, highlighting their commonalities and specific use cases.
• Identify and explain the purpose of other common Spring annotations (e.g., @Controller, @RestController, @Autowired, @Qualifier, @Configuration, @Bean, @Transactional).

8. Stream API

• Explain how to use the Java Stream API for functional-style collection processing (e.g., filtering, mapping, grouping, aggregation), providing examples of typical operations.