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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)
  • Kotlin collections (Lists; Set; Maps; Iterators)
  • Reading and Writing Files
See all covered skills

9 reasons why
9 reasons why

Adaface Kotlin Online Test is the most accurate way to shortlist Kotlin 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 expensive engineering time by filtering out unqualified candidates.

The Adaface Kotlin test screens candidates for the typical skills recruiters look for in a Kotlin developer:

  • Kotlin fundamentals (variables, strings, operators)
  • Nullability
  • Collections (list, set, map)
  • Lambdas and higher-order functions (common higher-order functions)
  • Object-oriented programming principles (Classes, objects, inheritance, polymorphism, abstraction, encapsulation)
  • Class types (Data, Enum, Sealed, Nested)
  • Standard functions and extension functions
  • Coroutines and asynchronous programming
  • File I/O
  • Exceptions Handling

The Kotlin Online test is designed to test for Kotlin fundamentals and hands-on coding skills. If you would like to test Android skills, then we design a custom test to evaluate Kotlin and Android skills in the same assessment. You can review our Android test to get a sense of our Android questions.

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.

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.

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.

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

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

How is the test customized for Senior Kotlin Developers?

The questions will test advanced topics for tests aimed at senior developers. Here are some topics that we use to create advanced Kotlin questions:

  • How to convert Java code into Kotlin
  • Understand how Java and Kotlin programs interoperate
  • Advanced OOP (Interface Classes, Abstract Classes, Generic Classes, Enums in Kotlin)
  • Advanced collections (MapOf, Arrayof, MutableList)
  • Asynchronous programming techniques (Threading, Callbacks, Futures, promises etc)
  • Reactive extensions and Coroutines

What roles can I use the Kotlin Online Test for?

  • Kotlin Developer
  • Android Kotlin Devloper
  • Android Developer - Java / Kotlin
  • Software Developer 1 (Kotlin)
  • Mobile Application Developer
  • Senior Kotlin Developer

What topics are covered in the Kotlin Online Test?

Variables & nullable types (null safety)
Conditionals: if and when
Loops: for and while
Functional programming
Web requests
Object-oriented programming
Creating classes and instances
String templates
Nullable values and null checks
Type checks and automatic casts
Data classes
Sealed classes
Generics: in, out, where
Nested and inner classes
Enum and inline classes
Object expressions and declarations
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 Online 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.

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
  • Web proctoring
  • Webcam proctoring
  • Plagiarism detection
  • Secure browser

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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