Java developer Interview Questions
Whether you are preparing to interview a candidate or applying for a job, review our list of top Java developer interview questions and answers.
- How would you describe your ideal development environment? See answer
- What are your favourite features of Java? See answer
- Tell us about your preferred Java frameworks. See answer
- Which method do you use while declaring a class in your Java code? See answer
- How do you adjust your Java development process while coming into a project with existing code? See answer
- How do you choose between HashSet and TreeSet when you need a set in Java? See answer
- How do you adjust your Java coding process if a project is lagging behind schedule? See answer
- How do you keep your code organised? See answer
- How do you maintain code quality while working on multiple projects with tight deadlines? See answer
- Explain the concept of polymorphism in OOP.
Ready to get started?
Post a job10 Java developer Interview Questions and Answers
How would you describe your ideal development environment?
The goal is to find the ideal conditions helpful to the candidate’s best work as a Java developer. A skilled Java developer will be able to answer this question with clarity, leveraging their experience to describe their ideal development environment.
What you should look for in an answer:
- Honest and direct communication
- Confidence and clarity concerning their role as a Java developer
- Awareness of the company’s layout and culture
Example:
I work best in an open-layout, cross-functional environment where I can physically interact and collaborate with my team members. However, I am also proficient in working remotely to adjust to your company’s flexible work culture.
What are your favourite features of Java?
The goal of this question is to ensure that the candidate has a strong understanding of every feature of Java and knows its differences compared to other programming languages.
What to look for in an answer:
- Extensive knowledge of Java
- Experience using Java
- They understand the benefits of the features of Java
Example:
I prefer using Java as it is an object-oriented programming system which is platform-independent. Java also has a high level of performance and speech, thus making it a highly useful programming language in the right context.
Tell us about your preferred Java frameworks.
A Java developer must be able to utilise Java frameworks to simplify coding and save time. This question helps you to test whether the candidate is a knowledgeable Java developer with the experience of working with Java frameworks.
What to look for in an answer:
- Knowledge of Java frameworks
- Experience working with Java frameworks
- Ability to explain their Java framework preferences
Example:
My preferred Java framework is Spring MVC, as it combines versatility and user-friendliness. I can code with ease by utilising the Spring MVC framework.
Which method do you use while declaring a class in your Java code?
This question helps you to test the candidate’s understanding of the fundamentals of Java coding.
What to look for in an answer:
- Clarity regarding classes in Java
- Ability to explain basic Java concepts
- Knowledge of Java coding
Example:
I aim to create generic classes to reduce my time writing redundant code. I analyse the classes I am working on and figure out a way to consolidate them into a generic class.
How do you adjust your Java development process while coming into a project with existing code?
Some of your projects may not require coding from scratch. This question helps you to learn if the candidate can work on already developed Java applications and adapt to another person’s code.
What to look for in an answer:
- They can quickly understand someone else’s code
- They seek assistance from team members to clear doubts regarding the code
- Ability to work with pre-written Java
Example:
While working on a project with pre-existing code, I thoroughly analyse the code and read the comments the previous Java developers left. Then after clearing my remaining doubts by consulting other team members, I am able to work on the project.
Explain the concept of polymorphism in OOP.
Polymorphism is an important OOP feature that enables code reusability and helps developers code more flexibly. This question can help you to test the candidate’s knowledge of Java and object-oriented programming.
What to look for in an answer:
- Conceptual clarity regarding polymorphism
- They understand the benefit of polymorphism in Java
- Knowledge of different types of polymorphism
Example:
Polymorphism is an OOP language feature that allows you to present one interface for implementing multiple data types. There are two types of Polymorphism in Java- compile-time or static polymorphism and runtime or dynamic polymorphism. You can utilise method overloading to achieve compile-time polymorphism and method overriding to achieve runtime polymorphism.
How do you choose between HashSet and TreeSet when you need a set in Java?
This question helps you to test the candidate’s decision-making and critical-thinking skills. The candidate can also cite practical examples where they had to choose between using HashSet or TreeSet.
What to look for in an answer:
- Analytical ability
- Knowledge of HashSet and TreeSet
- Decision-making skills
Example:
While a HashSet might seem superior at first glance, I prefer using TreeSet when I need to keep order over inserted elements or a query for inserted elements within a set. In my previous role, TreeSet helped me to look up multiple objects within the same time stamp, which would have needed additional programming to achieve by using HashSet.
How do you adjust your Java coding process if a project is lagging behind schedule?
Project overruns are fairly common in software development, so the candidate must be able to minimise the damage to the schedule. This question helps you to understand the candidate’s thought process and evaluate their time management skills.
What to look for in an answer:
- They prioritise the right parts of the Java development process
- Ability to respect crunch deadlines
- Coding efficiency
Example:
When a project is lagging behind, I analyse the project features required to meet the minimum viable product requirements for the next milestone. Then I prioritise coding these features until we get back on schedule.
How do you keep your code organised?
Employers ought to hire a Java developer who can keep their code organised since it makes it accessible for other coders who might work on the same project later. This question helps you to assess whether the candidate can keep their code organised and accessible for the development team.
What to look for in an answer:
- They are willing to keep the code organised
- Understanding of Java commenting best practices
- Experience working as part of a Java development team
Example:
After writing a section of code for a project, I review it and add helpful comments for the most important parts. This way, any other Java developer can easily understand my code if they need to work on the project later.
How do you maintain code quality while working on multiple projects with tight deadlines?
Java developers often work on multiple projects simultaneously to meet the company’s needs. This question helps you to learn how the candidate maintains code quality while negotiating steep deadlines.
What to look for you:
- Time management skills
- Professional work ethic
- Multitasking ability
Example:
First, I review each project’s deadlines and determine their difficulty level. Then, I structure my workday accordingly, dividing time between projects in a manner that helps me prioritise multiple projects. I also take numerous short breaks to stay alert and avoid making mistakes while coding for different projects.
*Indeed provides this information as a courtesy to users of this site. Please note that we are not your recruiting or legal advisor, we are not responsible for the content of your job descriptions, and none of the information provided herein guarantees performance.
Ready to get started?
Post a Job
Indeed’s Employer Resource Library helps businesses grow and manage their workforce. With over 15,000 articles in 6 languages, we offer tactical advice, how-tos and best practices to help businesses hire and retain great employees.