Top 10 Java Developer Interview Questions

Last Updated on 2024-10-11

Are you struggling to find a good Java developer? Worse yet, have you hired Java developers who ended up being a poor fit? Maybe you need to step up your interview process. We curated a list of Java developer interview questions that can help you find the best developers for your company.

The resume is an important item in job applications. If you are hiring a tech professional, the first thing you would want to look at is their resume. There you’ll find their claimed skills, work experience, educational background, and others. However, this document is not everything. 

During the interview, the hiring manager asks questions that can help them gain insight into the candidate’s professional and practical experience, accomplishments, and qualifications. Furthermore, this highlights the importance of a well-crafted list of interview questions.

Top Java Developer Interview Questions

Since the technical interview is essential in the entire hiring process, we prepared a few Java developer interview questions. Let’s start.

1. Which technologies you’ve listed in your resume did you have commercial experience within the past two years? What were your responsibilities and biggest accomplishments?

This question is most commonly asked to Java developers with more than three years of experience. Through this straightforward question, you can probe the applicant’s technical knowledge. Also, this question helps get to know the candidate better, whether they are an eager learner or a stagnant developer.

2. Explain object-orientated programming. Can you outline its benefits?

Java is known for its object-oriented programming structure. Real-world items or subjects turn into code as objects, and these objects communicate with other objects. Then, these objects interact to create a well-rounded application. 

As a Java developer, the candidate should completely explain and expound on the topic of OOP. Additionally, they should mention terms such as classes, abstraction, inheritance, and polymorphism.

3. What are some of the distinguishing features of Java Programming Language?

It is fairly difficult to assess a candidate’s programming skills from the resume alone. Asking the candidate to enumerate and expound on the common features of Java programming language helps examine the range of their knowledge. 

Sample answer:

Java programming language has the following features: simple, object-oriented, portable, platform-independent, secured, robust, distributed, and dynamic.

4. Why is Java not a pure object-oriented language?

As mentioned before, object-oriented programming is one of the core features of Java. However, this robust technology is not 100% object-oriented. That is because Java uses eight primitive data types: boolean, byte, char, int, float, double, long, and short. These data types are not objects. 

Sample answer:

Java is not purely object-oriented because it uses primitive data types that are not objects. However, it is object-oriented to the extent that it works in an object-oriented paradigm. This allows code management with the help of objects. 

5. What is the difference between path and classpath variables?

Classpath is Java-specific and is used by Java executables to locate class files. By asking this question, the interview can inspect if the candidate’s experience is indeed up to date in Java. 

Sample answer:

Path and Classpath are two different things. Path is an environment variable that tells the system where to look for executables, while Classpath is an environment variable that tells the system where to look for Java classes. The operating system uses Path to find executables, while Java uses Classpath to find classes. 

Path is used by the command line and is a system-wide environment variable. On the other hand, Java applications use Classpath, a user-specific environment variable. Furthermore, Path is set by the user, while the Java developer sets Classpath. Also, Path can be set in the .bashrc file, while Classpath can be set in the .bash_profile file.

Path and Classpath are two different things with two different purposes.

6. Give the difference between Heap and Stack Memory.

This Java developer interview question is very common. The applicant lacks knowledge of the two memory allocation methods if the candidate can’t give a definite answer on the difference between heap and stack. 

Sample answer:

Java uses Heap and Stack memory for different purposes:

– Heap memory is used for dynamic allocations.

– Stack memory is used for static allocations. 

When you create an object using new(), it’s stored in the heap, and when you create a reference variable, it’s stored on the stack. When you have a method, the parameters and local variables created inside that method will be stored on the stack. When the method finishes executing, all those variables are popped off the stack. So heap memory is used to store objects (created with new()), and stack memory is used for storing primitive variables and references. 

The main difference between heap and stack memory is that stack memory is programmed to deallocate when a function exits, whereas heap memory isn’t programmed to deallocate until program execution ends. 

So, objects created on the heap remain in scope until they’re explicitly deallocated, whereas objects on the stack go out of scope as soon as the function where they were created exits. The only way to access an object in the heap is through a pointer, while you don’t need a pointer to access an object on the stack. 

Finally, accessing an object on the heap is slower than accessing an object on the stack because it’s stored further away from other objects (on the call stack), while objects on the same call stack can quickly reference each other.

7. Give an example of a poorly-designed Java App

Questions related to coding practice and architecture help determine the knowledge of a Java developer in the field. As an interviewer, you will notice an experienced developer if they can recall apps they encountered that are terribly developed.

Candidates who fail to name one may not have dealt with failure. This may be a sign of inexperience, or they may have only worked with exceptional teams. However, a Java developer must know what a good and bad application is.

The applicant may start by mentioning how the faulty UI or poor coding practice led to a bad user experience or how poor code documentation and organization led to a nightmare code base. If the applicant is more enthusiastic, they may explain how the application may be improved.

8. What are constructors in Java?

In Java, constructors are code used to initialize an object’s state. This is basic knowledge when it comes to programming language. If the candidate falters from this question, it would indicate the developer lacks a basic foundation in Java. This also indicates inexperience and inadequate knowledge. 

9. Give 3 Benefits of Working in an Agile Team Environment

Agile software development is a popular software development methodology; any developer knows Agile. Agile offers a development team quick, robust, and secure app creation. By asking this question, the candidate has the chance to demonstrate their working knowledge when it comes to Agile principles and Scrum mentality. Furthermore, the candidate can explain what their role in the team is.

10. What Motivated You To Become a Java Developer?

Other than technical knowledge, it is also important to assess the candidate’s commitment. That is why you need to add this to your Java developer interview questions list. Ask them what drives them to work and choose to be a Java developer.

An employer will logically want to hire a candidate who is not just adept in technology but also passionate about it. Is this their language of choice, or are they simply willing to work with Java until they find their ideal role? Remember – an uninspired developer can decelerate the team’s productivity and lead to higher turnover.

Looking for Java Developers?

Java is one of the top three most desirable programming languages. With the rise of the era of applications comes the increase in demand for Java developers. This caused adversity for a lot of tech companies. It is becoming more and more difficult to hire competent and experienced developers. 

Where do you find qualified software developers? You can find them at Full Scale.

Full Scale is one of the most trusted offshore software development companies today. We specialize in recruiting, employing, and retaining the best software developers, testers, and leaders. With dozens of clients, hundreds of developers, and over 2 million coding hours delivered, we have a proven track record of success!

Hire a Java Developer from Full Scale today!