Top 20 Essential Java Interview Questions with Answers for Freshers with 1 to 2 years Experienced

If you are a grad looking for an internship position in a company that uses Java, or a fresher, just out from college and looking out for a Java development position, then this post is for you. I have attended, taken, and participated in a different level of Java interviews. I can say there is a vast difference between them, which is not surprising because you obviously want to ask different level questions based upon whether the candidate is fresher or experienced. Similarly, the problem at phone interview, written test, and face to face interviews, keeping this in mind, and give you always have a limited amount of time before going for an interview, It's essential to prepare the right set of questions.

Well, I can't guarantee that you will see questions from this set on your interview, but it gives you an idea about the level of questions you can expect in any Java internship or Software trainee positions.

Don't bother about multithreading and complex topic, only basic knowledge of threads is enough. Similarly, put more emphasis on the data structure, algorithms, and object-oriented basics like Inheritance, Composition, Encapsulation, Polymorphism, etc.

Similarly, Java interviews are not just about Java questions, it is also expected from you that you know computer fundamentals, basics of Linux and SQL, basics of designing software, coding, networking fundamentals, etc.

Once you have good ideas on those topics, you are ready for your interview. Though, if you are confused about how to prepare well for all those topics, I can suggest two ways, read a book like Cracking the Coding Interview by Gayle Laakmann McDowell, which contains 189 questions and their answers on all these topics.

basic questions for Java programmers



The second way is to join a course like Master The Coding Interview Bootcamp: Algorithms + Data Structures on Udemy. Though it is not as comprehensive as the Cracking the Coding Interview book, it does explain the most crucial thing algorithms and data structure.

Java fundamentals interview questions


You can also supplement your preparation through courses by joining a couple of others to prepare SQL, Java, Linux, etc. I have shared my full list of courses for coding interviews here, which contains some of the best routes to prepare well for programming job interviews.


Java Interview Questions for 1 to 2 years Experienced Programmers

Anyway, let's start with some of the basics Java questions a programmer with 1 to 2 years of experience should know.




1) What's, is Polymorphism in Java or OOP? (answer)


2) Given a reference to an abstract class Shape that has an abstract method named Draw, how does Java determine which version of the draw to call? What portion is handled at runtime, and what portion at compile time?  (answer)


3) what is the difference between an array and a linked list? How does this affect performance and memory usage? (answer)


4) Describe the garbage collection. What do mark and sweep mean? How about generational garbage collection? (answer)


5) what is the difference between a string literal and a string object? (answer)


6) what is the difference between int and Integer? (answer)


7) what is a binary search tree?  How do you implement it in Java? (answer)


8) what is a heap memory in Java? (answer)


9) how would you implement a priority queue in Java? (answer)


10) what does "Big O of n" mean in practice? Will an O(n) algorithm always outperform an O(n*n) algorithm? (answer)


Top 20 Java Interview Questions with Answers for Programmers with 1 to 2 years Experience11) What is the difference between a list and a linked list in Java? (answer)


12) What is a map in Java? (answer)


13) what is an array in Java? (answer)


14) What is a thread in Java? (answer)


15) What is a lock in Java? (answer)


16) What is deadlock? (answer)


17) Difference between Overloading and Overriding? (answer)


18) Difference between abstract class and interface? (answer)


19) Difference between Process and Thread in Java? (answer)


20) Difference between "extends" thread and "implements" Runnable? (answer)


That's all in this list of interview questions for preparing Java internship and Software developer positions. These questions are just to give you an idea of the level, which is expected from fresher’s and trainees. Keeping yourself on to a higher level will surely benefit you. Don't forget to share what kind of questions was asked of you in a fresher level interview.


Further Learning

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Thanks for reading this article so far. If you find these essential Java Interview questions useful then please share it with your friends and colleagues. If you have any questions or feedback, then please drop a note. 

P. S. - If you are looking for a free online course to prepare for Java interviews then you can also check out this free Object-Oriented Programming for Java interviews Udemy course. It's completely free and you just need an Udemy account to join this course online. 

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