1.What is Singleton in java and create your own singleton class countering all breakable conditions? 2. What is Auto Configuration? 3. @Primary vs @Qualifier 4. What is idempotent? 5. What is class loader? Types of class loader 6. Heap memory and stack memory 7. What is @Configuration and @bean? 8. Why is string immutable in java? 9. Write your own immutable class. 10. How Hashmap works internally? 11. What is Garbage Collector and how it works? 12. Checked vs unchecked exceptions 13. Throw vs Throws 14. What is Aggregation and Composition? 15. I want to add element inside a collection where duplicates won't be allowed and insertion order also be preserved. What should I use? 16. Limit vs Skip 17. Stream vs Parallel stream 18. Lock vs Synchronisation 20. Spring bean scopes 22. Monolithic vs Microservices 23. How Eureka works? 24. Why static and defaults methods are added inside interfaces?

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The interview questions cover various topics related to Java development, including Singleton pattern, memory management, exception handling, Spring framework, and design patterns.

Singleton pattern ensures a class has only one instance and provides a global point of access to it.
Auto Configuration in Spring Boot automatically configures the Spring application based on dependencies present in the classpath.
@Primary annotation is used to give higher preference to a bean when multiple beans of the same type are present, while @Qualifier is used to specify which bean to autowire.
Idempotent operations produce the same result regardless of how many times they are executed.
Class loader is responsible for loading classes into memory. Types include Bootstrap, Extension, System, and Custom class loaders.
Heap memory is used for dynamic memory allocation, while stack memory is used for static memory allocation and method calls.
@Configuration annotation is used to define a configuration class in Spring, while @Bean annotation is used to define a bean in the Spring container.
String is immutable in Java to ensure security, synchronization, and performance.
HashMap works internally using an array of buckets to store key-value pairs. The key's hash code is used to determine the bucket location.
Garbage Collector in Java automatically reclaims memory by destroying objects that are no longer reachable.
Checked exceptions are checked at compile time, while unchecked exceptions are not checked at compile time.
Throw is used to throw an exception explicitly, while Throws is used to declare the exceptions that a method can throw.
Aggregation represents a 'has-a' relationship between objects, while Composition represents a 'part-of' relationship.
To add elements in a collection without duplicates and preserve insertion order, use LinkedHashSet.
Limit is used to restrict the number of elements in a stream, while Skip is used to skip a specified number of elements.
Stream processes elements sequentially, while Parallel stream processes elements concurrently.
Locks provide exclusive access to a shared resource, while Synchronization ensures only one thread can access a shared resource at a time.
Spring bean scopes define the lifecycle and visibility of a bean in the Spring container.
Monolithic architecture is a single unit with all components tightly coupled, while Microservices architecture breaks down the application into smaller, independent services.
Eureka is a service registry and discovery server in Netflix OSS for Microservices architecture.
Static and default methods in interfaces were added in Java 8 to provide backward compatibility and allow interfaces to have concrete methods.

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