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Published: 10/10/2022

Best 25+ senior Java & Kotlin & Fullstack developer interview questions and answers

Best 25+ senior Java & Kotlin & Fullstack developer interview questions and answers

If you’re looking for a senior Java or Kotlin developer, or even a full-stack engineer, you’re going to want to ask the right questions in order to find the best possible candidate. In this blog post, we will provide you with 25+ of the best interview questions and answers for these positions. These interview questions are designed to test a candidate’s skills and knowledge, so make sure you ask them during your interview. Keep reading to get started!

Icebreaking interview questions

These questions are a great way to start off an interview and help break the ice between the interviewer and interviewee. On the other hand, you need to always check if they are suitable in a particular case.

Icebreaking interview questions

#1 What are your strengths and weaknesses as a developer 

This question is a classic for a reason. It can help you get a sense of how self-aware the candidate is and whether they are able to take criticism. It is important to define it from day one.

Example answer:

My strengths as a developer include my attention to detail and my ability to think critically. My weaknesses include my tendency to be perfectionistic and my lack of experience with some newer technologies.

#2 If you could work on any project, what would it be?

Asking this kind of interview questions can help you learn more about whether they are interested in the software development field.

Example answer:

I would love to work on a project that involves machine learning or artificial intelligence. I think those technologies are really fascinating and have a lot of potential.

#3 How do you debug code when something goes wrong

This question helps you get a sense of the candidate’s debugging skills. On the other hand, you can check how they handle working under pressure or when stumbling upon a crisis situation.

Example answer:

I usually start by checking the code for obvious mistakes, like typos or incorrect variable names. If that doesn’t work, I’ll try to narrow down the problem by, for example, running the code in a debugger or looking at the logs.

#4 Why should we hire you over the other candidates for this position 

If you ask this question, you will be able to figure out what makes the candidate unique and why they are a good fit for the position.

Example answer:

I think I would be a great fit for this position because I have a lot of experience with, for example, Java and Kotlin, which are both important technologies for this role. I’m also familiar with full-stack development, so I can take on a variety of tasks.

#5 What is your favorite part of programming in Java or Kotlin or full-stack development?

You can use this question to dig deeper into a candidate’s interests and what they are passionate about.

Example answer:

My favorite part of programming in Java is the huge community of developers who are always willing to help out. I also really like Kotlin’s syntax, which is more concise and expressive than Java. As for full-stack development, I enjoy being able to work on a variety of different tasks and technologies.

General interview questions

These questions are designed to test the candidate’s skills and knowledge.

General interview questions

#1 What is your typical workflow for implementing a new feature on a web platform or application?

You can use this question to get an impression of how the candidate streamlines their workflow.

Example answer:

I usually start by coming up with a plan for how I want to implement the feature. Then, I’ll write some test code and run it in a debugger to make sure it works. After that, I’ll start coding the actual feature and testing it as I go.

#2 How would you go about debugging errors in your codebase, and what are some common techniques that you use?

This question helps you get a sense of how competent the candidate is at debugging.

Example answer:

I usually start by checking the code for obvious mistakes, like typos or incorrect variable names. If that doesn’t work, I’ll try to narrow down the problem by running the code in a debugger or looking at the logs.

#3 What are some common security risks that occur in web development, and how can you mitigate them?

Assess the candidate’s security awareness with this question.

Example answer:

One common security risk in web development is cross-site scripting (XSS). This happens when an attacker injects malicious code into a website, which can then be executed by other users. To mitigate this risk, you can use a tool like Cross-Site Scripting Guard.

#4 Have you ever worked with any big data solutions, such as Apache Hadoop or Spark?

The purpose of this question is to gauge the candidate’s knowledge of big data solutions.

Example answer:

Yes, I have worked with both Apache Hadoop and Spark. I have also worked with other big data technologies like YARN. I’m familiar with the basics of working with big data, for example – loading data into HDFS and running MapReduce jobs.

In this question, you are trying to determine the candidate’s experience with web frameworks. Bonus points can be given if they spot what’s the difference between these two.

Example answer:

I have a lot of experience with Ruby on Rails and ExpressJS. I’ve worked with both frameworks for several years, and I’m familiar with their respective APIs. I’m also familiar with some other popular web frameworks, such as Laravel and Django.

Java Developer-specific questions

Java Developer-specific questions

#1 What is a polymorphic method, and how can you use it in your code?

This question tests the candidate’s understanding of polymorphism.

Example answer:

A polymorphic method is a method that can be called on different types of objects. This allows you to write code that is less specific about the type of object it is dealing with. For example, you could call the same method on an Array and a List, even though they are different types of objects.

#2 What is the difference between an interface and abstract class in Java?

Candidates are tested on their knowledge of interfaces and abstract classes in this question.

Example answer:

An interface is a type of class that defines a set of methods but does not implement them. This allows other classes to inherit from it, and then implement the methods themselves. An abstract class is a type of class that can only be used as a parent class. It defines a set of methods, but does not implement them. This allows other classes to inherit from it and then implement the methods themselves.

#3 What is a lambda expression in java, and how can you use it?

The candidate must prove they understand lambda expressions in this question.

Example answer:

A lambda expression is a short form for an anonymous function. It allows you to write code that takes advantage of functional programming features, such as closures and higher-order functions. You can use lambda expressions wherever you would normally use a regular function, if there is a case.

#4 What are some of the differences in syntax from C to Java?

The purpose of this question is to test the candidate’s understanding of the differences in syntax between C and in Java programming language. What is the key difference here?

Example answer:

Some of the biggest differences in syntax are that Java uses square brackets instead of parentheses for method calls, and that semicolons are mandatory at the end of every statement. In addition, there are some smaller changes, for example the way you declare variables and the way you use curly braces to define blocks of code.

#5 What is the difference between static and non-static methods in Java

Candidates are tested on their understanding of static and non-static methods in this question.

Example answer:

A static method is a method that belongs to a class, rather than an instance of a class. This means that you can call it without creating an instance of the class first. A non-static method is a method that belongs to an instance of a class. In other words, this means that you can only call it if you have an instance of the class.

Is it easy for you to answer these interview questions, fellow senior Java developer?

Come and join us at DAC.digital – we’re looking for a Remote Java developer.  

Kotlin-specific questions

Kotlin-specific questions

#1 Kotlin has a number of features that are not found in Java. What is your favorite feature of Kotlin, and why?

This question tests the candidate’s understanding of Kotlin. They should provide an example of features they like in this programming language.

Example answer:

My favorite feature of Kotlin is its support for lambdas. This allows you to write code that is more concise and expressive. It also makes it easier to use functional programming features.

#2 What is the difference between a class and an object in Kotlin?

The question assesses the candidate’s knowledge of classes and objects in Kotlin. If they can point out what is the difference between these terms, it’s a good indicator for the interview without keeping the suspense.

Example answer:

A class is a template for creating objects. It defines the properties and methods that all instances of the class will share. An object is an instance of a class. It has its own copy of the properties and methods defined by the class, and can also have its own local properties and methods.

#3 Give an example of when to use each type of variable in Kotlin

In this question, you will determine whether the candidate knows when to use classes, vals, and vars in Kotlin.

Example answer:

Class variables are best used when you need to share a value between all instances of a class. Val variables are best used when you need to store an immutable value. Var variables are best used when you need to store a mutable value.

#4 How would you define a function with multiple parameters in Kotlin

This question will test the candidates’ understanding of Kotlin function parameters.

Example answer:

You can define a function with multiple parameters by declaring a tuple type. The first element of the tuple is the name of the function, and the remaining elements are the parameter types. For example, you could define a function that takes two ints as parameters like this:

fun multiply(x: Int, y: Int) {}

You can also use the spread operator to pass multiple values into a function as if they were one parameter. For example, you could call the multiply function above like this:

multiply(12, 34) // Returns 408

#5 What are the different types of classes in Kotlin, and what are their purposes?

This question checks the candidate’s understanding of class types in Kotlin.

Example answer:

There are three types of classes in Kotlin: singleton, object, and companion. A singleton class is a class that can only have one instance. An object class is a class that can have multiple instances. A companion class is a class that is attached to another class and can only be accessed from within that other class.

Were these interview questions a piece of cake for you to answer? Seems like you’d be a great Remote Kotlin Developer at DAC.digital, then!

Fullstack questions

Fullstack questions

#1 What is your experience with various web development frameworks (AngularJS, ReactJS, VueJS, etc)?

The question evaluates the candidate’s experience using web development frameworks.

Example answer:

I have experience with both AngularJS and ReactJS. I prefer ReactJS because it allows you to create reusable components, which makes development more efficient. I am also familiar with VueJS, but I haven’t had a chance to use it in production yet.

Candidates are tested on their familiarity with popular web development frameworks in this question.

Example answer:

I have worked with Ruby on Rails and Laravel in the past. I prefer Ruby on Rails because it is more concise and expressive than Laravel. However, both frameworks are good options for developing web applications.

#3 Have you ever built a REST API from scratch before and if so, could you share some of your experiences/challenges with us?

This question tests the candidate’s experience with REST API development.

Example answer:

I have developed REST APIs from scratch before, and I found it to be a challenging but rewarding experience. For example, one challenge that I encountered was ensuring that my API was compliant with the various specifications (e.g., JSON-LD, HAL, etc.). Another challenge was handling errors gracefully. I was able to overcome these challenges by using the right tools and libraries.

#4 Do you have any experience working with front-end libraries such as React or Angular and if so, could you tell us how that went for you?

With this kind of interview questions, candidates are evaluated on their React and Angular experience.

Example answer:

I have experience working with both React and Angular. I prefer React because it allows you to create reusable components, which makes development more efficient. I also find that React is more performant than Angular. However, both frameworks are good options for developing web applications.

#5 Could you walk us through the steps involved in setting up a server-side rendered Angular application using NodeJS and ExpressJS?

In this question, the candidate is tested on their experience with setting up server-side rendered Angular applications.

Example answer:

Here are the steps involved in setting up a server-side rendered Angular application using NodeJS and ExpressJS:

  • Install NodeJS and ExpressJS.
  • Create a new project folder and cd into it.
  • Create a package.json file and install the required dependencies.
  • Create an index.js file and require the necessary modules.
  • Set up your server configuration in ExpressJS.
  • Mount your Angular application in ExpressJS.
  • Start your server and test it out!

Dear senior Fullstack developer, were these interview questions easy to answer?

Come and join us as a Remote FullStack Developer.  

Over to you

Questions — and answers — on developer interviews are like a box full of chocolates: you never know what you’re going to get. But that’s okay, because we’ve got you covered! In this blog post, we’ll give you a taste of the questions – and answers! — that you might encounter as a potential employee, and ask as a potential HR person, in a Java or Kotlin interview for a senior developer role.

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