📚 Main Topics Covered

1. Java Collections and Enhancements

   • Latest enhancements in HashMap (Java 8)
   • Introduction to the Optional class

2. Java 8 Functional Programming

   • Differences between map and flatMap

3. Design Patterns

   • Differences between Factory and Abstract Factory design patterns

4. Spring Framework

   • Different scopes in Spring
   • Differences between Spring and Spring Boot
   • Introduction to Spring AOP (Aspect-Oriented Programming)

5. Garbage Collection

   • Explanation of Metaspace and its differences from PermGen

6. Exception Handling

   • Explanation of multi-catch blocks in Java

7. Hibernate

   • Benefits of Criteria API in Hibernate
   • Types of cascade operations supported by JPA

8. Microservices

   • Definition and advantages of microservices architecture

✨ Key Takeaways

• HashMap EnhancementsJava 8 improved HashMap performance by replacing linked lists with balanced trees, reducing worst-case time complexity from O(n) to O(log n).
• Optional ClassA utility to prevent null pointer exceptions by providing a container that may or may not hold a value.
• Functional Programmingmap is for one-to-one transformations, while flatMap is for one-to-many transformations and flattening collections.
• Design PatternsFactory creates objects, while Abstract Factory creates factories that return objects.
• Spring ScopesSingleton and Prototype are the most common scopes, with Request, Session, and Global Session being less frequently used.
• Spring BootSimplifies Spring framework usage by reducing boilerplate code and managing dependencies.
• AOPSegregates cross-cutting concerns from business logic, enhancing modularity.
• Garbage CollectionMetaspace allows dynamic memory allocation for class metadata, unlike the fixed-size PermGen.
• Exception HandlingMulti-catch blocks allow handling multiple exceptions in a single catch statement.
• HibernateCriteria API allows dynamic query creation without hard-coded SQL, and JPA supports various cascade operations for entity relationships.
• MicroservicesPromotes independent service deployment, resilience, scalability, and faster time to market.

🧠 Lessons Learned

• Understanding the enhancements in Java collections and the functional programming paradigm is crucial for modern Java development.
• Familiarity with design patterns and frameworks like Spring and Hibernate is essential for building scalable applications.
• Knowledge of microservices architecture is increasingly important for developing robust and maintainable software systems.