Java Developer Interviews

Java Developer Interview Questions

In your interview for a java developer position, be prepared to answer technical questions that test your understanding of Java basics. Interviewers may also ask open-ended questions to assess your coding and problem-solving abilities. Prepare for non-technical questions that focus on time management, interpersonal communication, and work ethic.

Top Java Developer Interview Questions & How to Answer

Question 1

Question #1: What is the difference between HashTable and HashMap in Java?

How to answer
How to answer: Interviewers use technical questions to assess your formal training and understanding of the Java programming language. Use your answer to demonstrate your communication skills. Even if you have been coding for some time, it can be helpful to review Java basics before your interview.
Question 2

Question #2: Write a program to determine if 243 is an Armstrong number.

How to answer
How to answer: Interviewers use open-ended questions to test your coding skills. This question allows the employer to assess your ability to solve a problem using a Java algorithm. Explain your thinking process as you use a code editor or whiteboard to solve the problem.
Question 3

Question #3: How do you produce quality code when you have several Java projects to complete at once?

How to answer
How to answer: Java developers often juggle multiple projects at the same time. Interviewers use questions such as this to test your time management and organizational skills. Employers are also trying to assess your commitment to quality work. If you have experience as a developer, include examples from your work history that demonstrate high-quality work and effective time management.

30,885 java developer interview questions shared by candidates

Company for some reason makes a strong accent on concurrency initially. I was asked to create a load balancer with the production like code. You won't be given any requirements initially but only to implement the register method. Tried to clarify all the requirements ( target groups, healthchecks etc. ) From the interviwer answers I realized I shouldn't clarify requiments at this point. More requirements will be added added like capacity limitation and uniqueness check. why do you prefer register(String url) over register(URL url)? in what case the array list append won't be constant time? why it's not ready for prod ( concurrency ) what problems do you see? what's the simplest was to fix it? Didn't receive any feedback so it's hard to tell what was expected.
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Senior Java Developer

Interviewed at Revolut

4
May 26, 2025

Company for some reason makes a strong accent on concurrency initially. I was asked to create a load balancer with the production like code. You won't be given any requirements initially but only to implement the register method. Tried to clarify all the requirements ( target groups, healthchecks etc. ) From the interviwer answers I realized I shouldn't clarify requiments at this point. More requirements will be added added like capacity limitation and uniqueness check. why do you prefer register(String url) over register(URL url)? in what case the array list append won't be constant time? why it's not ready for prod ( concurrency ) what problems do you see? what's the simplest was to fix it? Didn't receive any feedback so it's hard to tell what was expected.

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Glassdoor has 30,885 interview questions and reports from Java developer interviews. Prepare for your interview. Get hired. Love your job.