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Fresher Java Interview

#technology#java#interview#backend

Updated: 2026-09-24

Sharing the interview process for a Fresher Java Backend Developer position at a certain fintech company (half a month ago):

Round 1: CV scan (if you pass, move to round 2) Round 2: Phone interview where HR runs a brief OOP test and an English test (if you pass, wait for the team to review your CV before round 3, face-to-face) Round 3: Go to the office to interview with HR and a tech lead sitting together, with the following set of questions (I only remember 95% of the questions that day) (The interview is in Vietnamese, folks)

  • Greeting and general self-introduction
  • Overview of your study and work history
  • OOP:
    • Compare abstract class vs interface
    • Compare abstract vs inheritance
    • Test case: can you implement method logic inside that class? Why?
    • When implementing an interface or extending an abstract class, do you need to override the methods? In which cases not?
    • Do you need to re-implement methods when extending a parent class?
    • Compare the @Override annotation/method overriding vs overloading
  • Java core:
    • Give an overview of the basic collection interfaces
    • Compare list vs set (performance, principle, use case, why use)
    • Compare LinkedList vs ArrayList (performance, principle, use case, why use)
    • Compare ArrayList vs an ordinary dynamic array (use case)
    • What is the difference between Integer and int (type, instance or variable, memory saving ...)
    • Pass-by-value & pass-by-reference (equals() vs ==: which kind of comparison, why they differ, and when to use each)
    • Have you worked with Java files? (I said not yet, so we skipped)
    • The static keyword in Java (use case, why use it -> what is a static method for)
    • There were more questions, but they were easy and I've completely forgotten them
  • Design patterns
    • What is MVC? Explain each part
    • Classify the types of design patterns
    • Present whichever design patterns you know: singleton, DI, repository, factory, MVC
  • Database
    • How do you connect to a database? What does it involve?
    • How many kinds of joins do you know? Explain them (inner, left, and right)
    • Compare and explain the concepts of MongoDB vs MySQL
  • Others:
    • How do you use beans in Spring, and why use beans (XML + annotations; it's a plus to also explain how a Spring app executes)
    • Compare GET vs POST, and POST vs PUT
    • Why use POST to create and PUT to update? Can they be swapped? (I only half-answered this one)
    • Why are GET and POST not enough that PUT, DELETE, and the rest were invented?
    • Which framework do you use to manage the database (Hibernate vs JDBC)? Compare the two and their use cases
    • How do you manage transactions/caching? What do you use?
    • Firebase SDK overview
    • Asked about the tools/GUIs you have used, such as MySQL Workbench, Sourcetree, Trello, ...
    • Asked how you manage git and whether you have any templates
    • Asked about concurrency & multithreading (I had just studied event sourcing, so I got asked, hehe)
    • Test case: many simultaneous requests that you don't want to synchronize (process in order) - what then? (queue + event sourcing, hehe -> explain it a bit)
    • Asked whether you have ever used Thymeleaf; if not, how do you do the FE? (I answered ReactJS and they only asked for a quick overview)
    • Which way have you used authentication vs authorization? (a short explanation and what you did with it and how is enough)
    • Then asked whether you have learned Spring Security (I had just finished a free course, so they only asked for a quick overview of the concepts)
    • Do you write tests? (I said I write unit tests, then they asked how, and when they asked about MockMvc I said I had only just looked into it and not applied it)

P.S. I studied Electronics and Telecommunications (ĐTVT) until the end of year 3 (you could say slightly off-field)

While I'm at it, I'll also share some questions from an interview about 2 months ago at an outsourcing company in HCM

Fresher Java Backend

Round 1: CV screening Round 2: IQ test + English interview with HR. Mostly normal conversation. Round 3: Interview with 2 leads

  • First, a self-introduction, the school projects you did, and questions about the technologies used, how you implemented them, and what you used them for
  • OOP:
    • The concept of inheritance, with a concrete example of inheritance
    • Polymorphism in Java (the concept, and the 2 kinds of polymorphism in Java)
    • Overloading vs Overriding
    • Abstract class vs Interface
  • Java core
    • Some specific declarations with the static keyword (roughly: applying the keyword to methods and variables - is it allowed in this case / what is it for)
    • The same as above for the final keyword
    • Compare ArrayList and LinkedList, and when to use each
    • What are Set and Map, what are HashSet and HashMap, and when to use them
    • How do you understand primitive types in Java?
  • Design Pattern:
    • The MVC model
    • Take a login page as an example: describe how MVC operates when a user logs in through the login page
  • Database:
    • Distinguish the WHERE and HAVING clauses
    • The types of joins in a database, followed by a concrete example (what result do you get when applying this join to 2 tables with this data)
    • What is a transaction, what is it commonly used for? What happens when a transaction fails?
  • Miscellaneous:
    • Commonly used HTTP methods, their concepts and differences
    • When implementing the controller, do you use POST or GET for login, and why? Could you use GET?
    • Given some code snippets, write on paper the output after running them
    • A few more questions on JPA and Hibernate that I don't remember well

See also: Fresher Backend Interview · Oracle Interview Gandhinagar · Interview Questions