12 Multithreading Interview Questions for Java Developers

12 Multithreading and concurrency interview questions with answers for Java programmers

Hello guys, Multithreading is an important feature of the Java programming language, which means threads are also an important part of any Java interview.

It's true and in fact, at beginners and freshers, level multithreading interview questions in Java are one of the most difficult to answer.

One reason for interview questions related to multithreading and concurrency being difficult is confusion around how multiple threads work together and the second is threads are genuinely a complicated topic to understand and use correctly.

Mostly thread interview questions check Java programmer's knowledge on Java Thread API, Java concurrency API, issues related to multi-threading like a race condition, thread-safety, and deadlock.

Some time multithreading and concurrency interview question also focus on parallel design patterns like solving the producer-consumer problem, implementing work steal pattern, or solving dining philosopher problem in Java.

This is especially true while interviewing experienced Java developers with 4 to 6 years of experience.

In the past few posts, I have shared popular Java interview questions like,, How ConcurrentHashMap work in Java? Why String is Immutable, why wait() and notify() is called from synchronized context, and difference between List, List<Object> and In this article, I will share popular multithreading questions from interviews.

You will learn about multithreading and concurrency questions asked in various interviews like on telephonic or face-to-face interviews, on written tests, to both experienced and senior Java developers, and some tips to answer them correctly.

Btw, if you are a complete beginner to Java threads, I strongly suggest you join a hands-on multithreading course like Multithreading and Parallel Computing in Java from Udemy. It's a great course to learn thread basics It's also very affordable and you can get in just $10on Udemy sales.

12 Java Multithreading Interview Questions and Answers

As I said, in this Java article, not only,  I will share some of the most commonly asked thread interview questions at the freshers and beginners level, like up to 2 to 4 years of experience, and some tips and tricks to answer them correctly.

By the way, these thread interview questions are equally useful for senior Java developers or guys with some Java experience in hand.

I have tried to share answers to these interview questions on the thread as well but I suggest you do some research and learn the topic well to answer any follow-up questions, which comes due to your response to these thread questions in Java.

Anyway here is my collection of Java thread interview questions and how to answer them in Java :

1. What is the difference between the start and run method in Java Thread?

This thread interview question is also asked as if the start() method eventually calls the run() method then why do you need to call the start() method, why not call the run() method directly.

Well, the reason is that because start method creates a new thread and calls the code written inside the run method on a new thread while calling the run method executes that code on the same thread.

2. Can you write code to avoid deadlock in Java where N threads are accessing N shared resources?