My previous post was about recruitment practices read here. Today I want to share with you a list of Java interview questions which were asked me.

Even if you are senior developer you need to be prepared to answer questions about: JAVA COLLECTIONS

Yes, it’s still up to date and it’s important to remember about Java basics. Example questions:

• list mainly used Java collections interfaces with implementations
• how HashSet/HashMap works
• which list implementation is faster in adding new elements
• describe time complexity of each operation in List/Set/Map collections

Another category of questions was about: JAVA OBJECTS

Technical recruiters asked me about:

• OOP in Java
• difference between interface and abstract class
• contract between equals and hashCode methods
• rules of SOLID acronym

Senior developers must be prepared to answer more advanced questions like:

• explain Java memory management model
• how garbage collector works
• can garbage collector delete object with reference (tricky question about circular reference in non used objects)
• list known JVM flags and their meaning

After pure Java questions it was time to check knowledge about popular frameworks: SPRING AND HIBERNATE

Often repeated questions where:

• explain optimistic locking in Hibernate and how to deal with it
• n+1 problem - what it is and how to solve this
• list types of Spring beans and describe how we can create them
• advantages and disadvantages of Spring framework
• describe support for transaction management in Spring

Except Java related questions candidates must answer SQL related questions:

• join clauses
• filter data with where, having clauses
• describe how indices in RDMS works

Nowadays developers are not only programming, they also work with application servers, CI/CD systems. Recruiters asked me about my knowledge of Jenkins, Bamboo and other similar tools. Version control systems like Git where also topic of some questions.

Some recruiters had prepared questions about good coding practices and design patterns - but it was not a rule.

I noticed that technical recruiters in bigger companies had strict list of interview questions. Recruiters in smaller companies where more flexible and they tried to fit questions to my previous projects and used technologies.

In next post I will list questions asked by me to the recruiters :)

Hope you enjoy this post. If you have any questions or problems leave a comment or send email.