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About the test:

The Kotlin Online Test uses scenario-based and code tracing MCQ questions to evaluate a candidate's ability to use Kotlin basics (Variables, Strings), Kotlin Collections (List, Map, Set, Iterators), and Kotlin OOPs (classes, inheritance, interfaces) to develop null-safe, concise and readable Kotlin code. The test has coding questions to evaluate hands-on Kotlin programming skills.

Covered skills:

  • Kotlin basics (Variables; Strings; Functions)
  • Object-Oriented Programming (Classes; Inheritance)
  • Standard functions (apply; let; with; run)
  • Working with APIs
  • Asynchronous Programming (Coroutines)
  • Kotlin collections (Lists; Set; Maps; Iterators)
  • Reading and Writing Files
  • Extension functions
  • Adding dependencies

9 reasons why
9 reasons why

Adaface Kotlin Test is the most accurate way to shortlist Android Developers

Reason #1

Tests for on-the-job skills

The Kotlin Online Test helps recruiters and hiring managers identify qualified candidates from a pool of resumes, and helps in taking objective hiring decisions. It reduces the administrative overhead of interviewing too many candidates and saves time by filtering out unqualified candidates at the first step of the hiring process.

The test screens for the following skills that hiring managers look for in candidates:

  • Ability to understand and use variables, strings, and functions in Kotlin
  • Understanding and working with Kotlin collections such as lists, sets, maps, and iterators
  • Knowledge of object-oriented programming concepts like classes and inheritance in Kotlin
  • Familiarity with reading and writing files in Kotlin
  • Understanding and utilization of standard Kotlin functions like apply, let, with, and run
  • Ability to create and use extension functions in Kotlin
  • Experience in working with APIs in Kotlin
  • Knowledge of adding and managing dependencies in Kotlin
  • Understanding of asynchronous programming with coroutines in Kotlin
Reason #2

No trick questions

no trick questions

Traditional assessment tools use trick questions and puzzles for the screening, which creates a lot of frustration among candidates about having to go through irrelevant screening assessments.

View sample questions

The main reason we started Adaface is that traditional pre-employment assessment platforms are not a fair way for companies to evaluate candidates. At Adaface, our mission is to help companies find great candidates by assessing on-the-job skills required for a role.

Why we started Adaface
Reason #3

Non-googleable questions

We have a very high focus on the quality of questions that test for on-the-job skills. Every question is non-googleable and we have a very high bar for the level of subject matter experts we onboard to create these questions. We have crawlers to check if any of the questions are leaked online. If/ when a question gets leaked, we get an alert. We change the question for you & let you know.

How we design questions

These are just a small sample from our library of 10,000+ questions. The actual questions on this Kotlin Online Test will be non-googleable.

🧐 Question


twoWheeler Interface
What will the following code output?


Secondary Constructor
What does the following Kotlin code print?


Registration Queue
We want to register students for the next semester. All students have a receipt which shows the amount pending for the previous semester. A positive amount (or zero) represents that the student has paid extra fees, and a negative amount represents that they have pending fees to be paid. The students are in a queue for the registration. We want to arrange the students in a way such that the students who have a positive amount on the receipt get registered first as compared to the students who have a negative amount. We are given a queue in the form of an array containing the pending amount.
For example, if the initial queue is [20, 70, -40, 30, -10], then the final queue will be [20, 70, 30, -40, -10]. Note that the sequence of students should not be changed while arranging them unless required to meet the condition.
⚠️⚠️⚠️ Note:
- The first line of the input is the length of the array. The second line contains all the elements of the array.
- The input is already parsed into an array of "strings" and passed to a function. You will need to convert string to integer/number type inside the function.
- You need to "print" the final result (not return it) to pass the test cases.

For the example discussed above, the input will be:
20 70 -40 30 -10

Your code needs to print the following to the standard output:
20 70 30 -40 -10


Visitors Count
A manager hires a staff member to keep a record of the number of men, women, and children visiting the museum daily. The staff will note W if any women visit, M for men, and C for children. You need to write code that takes the string that represents the visits and prints the count of men, woman and children. The sequencing should be in decreasing order. 


Expected Output: 

‘W’ has the highest count, then ‘C’, then ‘M’. 
⚠️⚠️⚠️ Note:
- The input is already parsed and passed to a function.
- You need to "print" the final result (not return it) to pass the test cases.
- If the input is- “MMW”, then the expected output is "2M1W" since there is no ‘C’.
- If any of them have the same count, the output should follow this order - M, W, C.
🧐 Question🔧 Skill


twoWheeler Interface

3 mins



Secondary Constructor

2 mins



Registration Queue

30 mins



Visitors Count

30 mins

🧐 Question🔧 Skill💪 Difficulty⌛ Time
twoWheeler Interface
Easy3 mins
Secondary Constructor
Easy2 mins
Registration Queue
Easy30 minsSolve
Visitors Count
Medium30 minsSolve
Reason #4

1200+ customers in 75 countries

customers in 75 countries

With Adaface, we were able to optimise our initial screening process by upwards of 75%, freeing up precious time for both hiring managers and our talent acquisition team alike!

Brandon Lee, Head of People, Love, Bonito

Reason #5

Designed for elimination, not selection

The most important thing while implementing the pre-employment Kotlin Online Test in your hiring process is that it is an elimination tool, not a selection tool. In other words: you want to use the test to eliminate the candidates who do poorly on the test, not to select the candidates who come out at the top. While they are super valuable, pre-employment tests do not paint the entire picture of a candidate’s abilities, knowledge, and motivations. Multiple easy questions are more predictive of a candidate's ability than fewer hard questions. Harder questions are often "trick" based questions, which do not provide any meaningful signal about the candidate's skillset.

Science behind Adaface tests
Reason #6

1 click candidate invites

Email invites: You can send candidates an email invite to the Kotlin Online Test from your dashboard by entering their email address.

Public link: You can create a public link for each test that you can share with candidates.

API or integrations: You can invite candidates directly from your ATS by using our pre-built integrations with popular ATS systems or building a custom integration with your in-house ATS.

invite candidates
Reason #7

Detailed scorecards & benchmarks

View sample scorecard
Reason #8

High completion rate

Adaface tests are conversational, low-stress, and take just 25-40 mins to complete.

This is why Adaface has the highest test-completion rate (86%), which is more than 2x better than traditional assessments.

test completion rate
Reason #9

Advanced Proctoring

Learn more

About the Kotlin Assessment Test

Why you should use Pre-employment Kotlin Online Test?

The Kotlin Online Test makes use of scenario-based questions to test for on-the-job skills as opposed to theoretical knowledge, ensuring that candidates who do well on this screening test have the relavant skills. The questions are designed to covered following on-the-job aspects:

  • Knowledge of Kotlin basics including variables, strings, and functions
  • Understanding of Kotlin collections such as lists, set, maps, and iterators
  • Proficiency in object-oriented programming concepts including classes and inheritance
  • Ability to read and write files in Kotlin
  • Familiarity with standard functions like apply, let, with, and run
  • Experience with extension functions in Kotlin
  • Skill in working with APIs in Kotlin
  • Understanding of adding dependencies in Kotlin projects
  • Knowledge of asynchronous programming using coroutines
  • Proficient in handling exceptions and errors in Kotlin
  • Ability to use control flow statements for decision making

Once the test is sent to a candidate, the candidate receives a link in email to take the test. For each candidate, you will receive a detailed report with skills breakdown and benchmarks to shortlist the top candidates from your pool.

What topics are covered in the Kotlin Online Test?

  • Kotlin basics

    Kotlin basics covers the foundational concepts of the Kotlin programming language, including variables, strings, and functions. Understanding these basics is crucial as they form the building blocks for any Kotlin application.

  • Kotlin collections

    Kotlin collections enable the organization and manipulation of data. This skill covers various types of collections such as lists, sets, maps, and iterators, which are essential for efficient data handling in Kotlin applications.

  • Object-Oriented Programming

    Object-Oriented Programming (OOP) is a paradigm used to model real-world entities through classes and objects. This skill focuses on concepts like classes, inheritance, and polymorphism, which play a key role in designing modular and maintainable Kotlin code.

  • Reading and Writing Files

    Reading and writing files is a fundamental skill for accessing and manipulating data stored in files. By understanding this skill, developers can efficiently interact with external resources and handle operations such as reading from and writing to files in Kotlin.

  • Standard functions

    Standard functions in Kotlin, such as apply, let, with, and run, provide concise syntax to perform common operations. Mastery of these functions enhances code readability, reusability, and overall code quality in Kotlin.

  • Extension functions

    Extension functions allow developers to extend existing classes with additional functionalities. This skill enables developers to write concise and reusable code by defining extension functions that enhance the capabilities of existing Kotlin classes.

  • Working with APIs

    Working with APIs involves integrating external services and retrieving data from various sources using network requests in Kotlin. This skill is essential for developing applications that interact with web services, databases, and other external resources.

  • Adding dependencies

    Adding dependencies in Kotlin allows developers to leverage existing libraries and frameworks to enhance their applications. Understanding how to add and manage dependencies is crucial for efficiently utilizing third-party code and minimizing development time.

  • Asynchronous Programming

    Asynchronous programming using coroutines enables developers to write non-blocking and efficient code that can handle concurrency and parallelism effectively. This skill is particularly important in modern application development, as it allows for smooth execution of time-consuming tasks without blocking the main thread.

  • Full list of covered topics

    The actual topics of the questions in the final test will depend on your job description and requirements. However, here's a list of topics you can expect the questions for Kotlin Online Test to be based on.

    Reading Files
    Writing Files
    Apply Function
    Let Function
    With Function
    Run Function
    Extension Functions
    Working with APIs
    Adding Dependencies
    Exception Handling
    Null Safety
    Type Inference
    Lambda Expressions
    Higher Order Functions
    Scope Functions
    Collections Operations
    File Input/Output
    Abstract Classes
    Object Declaration
    Visibility Modifiers
    Java Interoperability
    Lambda Functions
    Access Modifiers
    Kotlin DSL
    Named Arguments
    Operator Overloading
    Sealed Classes
    Smart Casts
    Data Classes
    Inline Functions
    Range Operations
    Unit and Nothing Types
    Lazy Initialization
    Lateinit Modifier
    Type Aliases
    Suspend Functions
    Flow Control
    Collection Functions
    String Interpolation
    Type Checking

What roles can I use the Kotlin Online Test for?

  • Android Developer
  • Kotlin Developer
  • Backend Developer
  • Full Stack Developer
  • Software Engineer
  • Mobile Developer
  • Frontend Developer
  • Java Developer

How is the Kotlin Online Test customized for senior candidates?

For intermediate/ experienced candidates, we customize the assessment questions to include advanced topics and increase the difficulty level of the questions. This might include adding questions on topics like

  • Familiarity with functional programming concepts in Kotlin
  • Experience with unit testing frameworks in Kotlin
  • Understanding of design patterns in Kotlin
  • Skill in using lambda expressions and higher-order functions
  • Knowledge of multi-threading concepts in Kotlin
  • Ability to create and use Kotlin data classes
  • Experience with handling nullable types and safe calls in Kotlin
  • Proficiency in using Kotlin's standard library functions and APIs
  • Understanding of serialization and deserialization in Kotlin
  • Ability to debug and troubleshoot Kotlin code effectively
  • Knowledge of memory management principles in Kotlin

The coding question for experienced candidates will be of a higher difficulty level to evaluate more hands-on experience.

Singapore government logo

The hiring managers felt that through the technical questions that they asked during the panel interviews, they were able to tell which candidates had better scores, and differentiated with those who did not score as well. They are highly satisfied with the quality of candidates shortlisted with the Adaface screening.

reduction in screening time

Kotlin Hiring Test FAQs

Can I evaluate Kotlin and Android in the same test?

Yes. We support testing multiple skills in the same test. You can review our standard Android test to get a sense of what kind of questions will be included to test Android skills. The final test will include MCQ questions to evaluate Kotlin, Android and coding questions to evaluate Kotlin.

Can I have Kotlin as an optional skill in the Android test?

Yes. We design custom chat flows where a few skills can be optional. For Android roles, typically we design tests where candidates are given a choice to choose their preferred programming language between Java and Kotlin. The bot will ask questions only on the chosen programming language. The coding questions can be restricted to desired programming languages. In this case, the candidate can choose between Java and Kotlin to write the code.

Can I combine multiple skills into one custom assessment?

Yes, absolutely. Custom assessments are set up based on your job description, and will include questions on all must-have skills you specify. Here's a quick guide on how you can request a custom test.

Do you have any anti-cheating or proctoring features in place?

We have the following anti-cheating features in place:

  • Non-googleable questions
  • IP proctoring
  • Screen proctoring
  • Web proctoring
  • Webcam proctoring
  • Plagiarism detection
  • Secure browser
  • Copy paste protection

Read more about the proctoring features.

How do I interpret test scores?

The primary thing to keep in mind is that an assessment is an elimination tool, not a selection tool. A skills assessment is optimized to help you eliminate candidates who are not technically qualified for the role, it is not optimized to help you find the best candidate for the role. So the ideal way to use an assessment is to decide a threshold score (typically 55%, we help you benchmark) and invite all candidates who score above the threshold for the next rounds of interview.

What experience level can I use this test for?

Each Adaface assessment is customized to your job description/ ideal candidate persona (our subject matter experts will pick the right questions for your assessment from our library of 10000+ questions). This assessment can be customized for any experience level.

Does every candidate get the same questions?

Yes, it makes it much easier for you to compare candidates. Options for MCQ questions and the order of questions are randomized. We have anti-cheating/ proctoring features in place. In our enterprise plan, we also have the option to create multiple versions of the same assessment with questions of similar difficulty levels.

I'm a candidate. Can I try a practice test?

No. Unfortunately, we do not support practice tests at the moment. However, you can use our sample questions for practice.

What is the cost of using this test?

You can check out our pricing plans.

Can I get a free trial?

Yes, you can sign up for free and preview this test.

I just moved to a paid plan. How can I request a custom assessment?

Here is a quick guide on how to request a custom assessment on Adaface.

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Ready to use the Adaface Kotlin Online Test?
40 min tests.
No trick questions.
Accurate shortlisting.
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