What is memory leak issue? What are common scenario of memory leak? Improper equals() and hashCode() Implementations What does Transactional annotation do? What is Liquibase Management? Docker image vs file vs container? Given an input array: 2 ,1 ,3 ,6 ,3 , 2 --> Print 2 (1st occurence of the maxFrequency number that has least index) Given class UserService, write JUnit test: class UserService { ///constructors, setters etc private DBService db; public List getUsers() { return db.listUsers(); } } Write a singleton class Round 2: Why use Builder design pattern if same can be done with getters and setters? Kafka is CA in CAP Benefits of micro service architecture? One disadvantage of micro service? Dependency management using maven, scope of dependency? https://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html Why they made string immutable in java? Can abstract class have constructor? How is concurrent map implemented? Synchronization in java? Object, Class and Method level