Vention | Final Interview

After successfull tech call, i was invited to final interivew. This interview consisted of two parts: 20m with recruiter, 40m with Team Lead. Below i will share some questions:

Interview with Recruiter

• Why do you want to leave Epam Systems?
• Why do you want to join Vention?
• How do you learn new technologies?
• Why you have chosen Java?
• What is your career goal?

Interview with Team Lead

Java Core

• Difference between Runnable and Collable?
• Can we create instance from class which has private constructor? (hint Singleton pattern)
• How to make ArrayList immutable?
• Why we need Wrapper classes?
• Contract between hashcode() and equals() method?
• What is the result of this code:

Map<String, String> map = new HashMap<>();
map.put(null, "String1");
map.put(null, "String2");
map.put(null, "String3");

Database

• Difference between MongoDB and PostgreSQL?
• Have you assigned to a task to improve performance of database? (hint index)
• What kind of indexes you know in PostgreSQL? (hint btree and b+tree)
• We have tables with column id and name, this table contains duplicates, how can i retrieve only unique values from this table? (hint self join)
• Difference between InnerJoin and OuterJoin?
• What is JDBC? What kind of queries we can have?
• Difference between PreparedQuery and SimpleQuery in JDBC?
• Difference between JPA and JDBC?

Hibernate

• What i need to make my class represent table using Hibernate annotation?
• What should i need to do to not load one to many relatioship fields?
• What is Proxy?

Spring

• What should i enable to create Spring Web application without Spring Boot? (hint Dispatcher Servlet)
• Can i create command line application with Spring Boot?
• Difference between @Controller and @RestController?
• What is the difference between @Bean and @Component?
• What is the default bean naming strategy in Spring?
• When we run our Spring application, which beans will be present in IoC container?