TestGorilla LogoTestGorilla Logo

Java (Coding): Data Structures test: Online screening assessment to hire the best candidates

All tests/Programming skills/
Java (Coding): Data Structures test
Type: Programming skills
Time: 30 min
Languages: English
Level: Intermediate

Summary of the Java (Coding): Data Structures test

This Java data structures test assesses a candidate’s ability to effectively manipulate core data structures in the Java programming language. In 30 minutes, they will work with the core Java API to implement typical and real-life scenarios.

Covered skills

  • Data structures

Use the Java (Coding): Data Structures test to hire

Any developer who is expected to have practical experience using Java. The difficulty level of these questions is geared to mid-level developers.

graphic for programming skills tests

About the Java (Coding): Data Structures test

Java is a general-purpose language used for distributed environments. It is one of the most popular programming languages for Android app development, embedded systems, desktop applications, and enterprise-grade systems.

Working with data structures is crucial to the success of a developer. Effective utilization of the core Java API and data structures enables developers to effectively organize, manage, and represent data. Data structures are often implemented as objects, so the ability to effectively work with objects and understanding object-oriented programming is an important skill to have.

This coding test presents a real-life scenario to your candidates. They have 30 minutes to implement a data structure that meets the given requirements. Candidates can run the code against a selected number of test cases to see if they are on track.

After submission, the code is automatically scored based on another set of test cases that also covers exceptions or corner cases. You will be able to play back how the code came about in the coding editor.

We recommend combining coding tests with one of our cognitive ability tests.

TestGorilla logo

The test is made by a subject-matter expert

Victoria S.

Victoria is a Senior/TL Java Developer with over 10 years of experience in software development, known for her creativity and passion for her work and clients.

She has deep experience in requirement analysis, project designing and implementation, team management, analysis of customer issues, code refactoring, and optimization.

Crafted with expert knowledge

TestGorilla’s tests are created by subject matter experts. We assess potential subject-matter experts based on their knowledge, ability, and reputation. Before being published, each test is peer-reviewed by another expert, then calibrated using hundreds of test takers with relevant experience in the subject.

Our feedback mechanisms and unique algorithms allow our subject-matter experts to constantly improve their tests.

What our customers are saying

TestGorilla helps me to assess engineers rapidly. Creating assessments for different positions is easy due to pre-existing templates. You can create an assessment in less than 2 minutes. The interface is intuitive and it’s easy to visualize results per assessment.

Review from G2
David Felipe C.

VP of engineering, mid-market (51-1000 FTE)

Any tool can have functions—bells and whistles. Not every tool comes armed with staff passionate about making the user experience positive.

The TestGorilla team only offers useful insights to user challenges, they engage in conversation.

For instance, I recently asked a question about a Python test I intended to implement. Instead of receiving “oh, that test would work perfectly for your solution,” or, “at this time we’re thinking about implementing a solution that may or may not…” I received a direct and straightforward answer with additional thoughts to help shape the solution.

I hope that TestGorilla realizes the value proposition in their work is not only the platform but the type of support that’s provided.

For a bit of context—I am a diversity recruiter trying to create a platform that removes bias from the hiring process and encourages the discovery of new and unseen talent.

Review from G2
High quality assessments
David B.

Chief Talent Connector, small business (50 or fewer FTE)

Use TestGorilla to hire the best faster, easier and bias-free

Our screening tests identify the best candidates and make your hiring decisions faster, easier, and bias-free.

Learn how each candidate performs on the job using our library of 400+ scientifically validated tests.

Test candidates for job-specific skills like coding or digital marketing, as well as general skills like critical thinking. Our unique personality and culture tests allow you to get to know your applicants as real people – not just pieces of paper.

Watch what TestGorilla can do for you

Create high-quality assessments, fast

Building assessments is a breeze with TestGorilla. Get started with these simple steps.

Building assessments is quick and easy with TestGorilla. Just pick a name, select the tests you need, then add your own custom questions.

You can customize your assessments further by adding your company logo, color theme, and more. Build the assessment that works for you.

View a sample report

The Java (Coding): Data Structures test will be included in a PDF report along with the other tests from your assessment. You can easily download and share this report with colleagues and candidates.

The importance of data structures in Java

With data demands for applications and programs constantly increasing, so too does the need for candidates with strong competencies in data structuring. This is simply because data structures are the core of any programming language. They are used in almost every aspect of computer science, including operating systems, artificial intelligence, and graphics processing.

In Java, data structures describe the logical organization of data and involve using algorithms to store data in a way that is easy and efficient to retrieve and use. In its essence, a data structure is a data collection with well-defined operations, behavior, or properties.

Humans use this concept to better visualize and understand how data is stored and retrieved. Therefore, it is important that Java developers understand how to use appropriate data structures that will improve an application’s performance.

Data structuring challenges in business

Alongside algorithms, data structures have become one of the most important disciplines in computer science. As data volume increases rapidly and applications become more complex, there is an increased need for effective data structures. In addition, data structures provide an efficient way to store data for future access.

This means that developers need to know how to effectively use the core Java API and data structures to organize, manage, and represent data. To achieve this, developers must have familiarity with the common operations in data structures, which include:

• Access: Storing data for future access based on the requirement

• Searching: Finding any element within data structures

• Sorting: Arranging data into ascending or descending order• Insertion: Adding new elements into a data structure

• Updating: Replacing an element with a different or new version of an element

• Deletion: Removing an element

Considerations for developers

In development, there are three primary considerations that influence effective memory organization. These are:

• Efficiency: The efficiency of data structures is related to the amount of data an algorithm must process. To increase the efficiency and performance of applications, data is organized in a way that requires less space but processes at a higher speed and thus also requires less time.

• Reusability: Data-structures reusability looks at the implementation of particular data structures that can be reused and replicated multiple times. The implementation of reusability in data structures allows the variable application of these libraries.

• Abstraction: In Java, the Abstract Data Types, or ADT, specify data structures. This means the client program uses the specified data structures with the help of only the interface, without needing to know any of the implementation’s details.

Having solid knowledge of the types of data structures is essential for all Java developers because it forms a fundamental part of the language. By determining if candidates have the necessary knowledge and skills to effectively implement data structures and understand the use of the different types of data structures, recruiters can easily hire the best person for the job. But how do you determine candidates’ skills? Let’s show you.

How to recruit developers with data structures knowledge

Candidates with good knowledge of data structures are able to write code that is efficient and reliable. They will be capable of solving development problems quickly and effectively. One way to determine if job applicants have the data-structures skills required for the position is by giving them a Java coding test.

Skills testing evaluates all your candidates on the same parameters, allowing you to quantify their individual expertise in the skills that are the most valuable to the open role. Additionally, skills testing allows you to rank applicants on the same scale. This helps you compare candidates and understand which individuals excel in which areas.

The benefits of pre-employment testing with a Java (Coding) Data Structures test

In recent years, skills testing has become a more popular way to recruit, because CVs don’t give recruiters and hiring managers adequate information on candidate skills. Skills testing helps you:

• Spend less time on unqualified candidates: Pre-employment testing helps you easily filter out unsuitable candidates and focus on the applicants that possess the necessary skills for the role.

• Improve your time to hire: By testing job applicants at the start of your recruitment process, you can review, rank, and sort candidates to help you focus on only the most qualified individuals.

• Reduce recruitment costs: By focusing on only the most skilled candidates, and improving your time to hire, you can reduce recruitment costs and make fewer mis-hires.

• Deliver an outstanding candidate experience: Applicants can take skills tests on any device, anywhere in the world. By recruiting with skills tests, applicants know that they will be judged solely on their skills and abilities.

• Test applicants regardless of experience level: One of the benefits of pre-employment testing is its ability to test candidates for a variety of job roles and levels of seniority.

• Validate candidates’ skills before interviewing: Pre-employment testing helps you to narrow down your selection of applicants and only interview the most qualified ones. In addition, testing enables you to learn more about candidates, which can help you in the interview process.

In summary

Using TestGorilla, you can evaluate job applicants and gain additional insights into their skills at the start of the recruitment process. Our pre-employment tests like the Java (Coding) Data Structures test help you streamline your recruitment process, eliminate unconscious bias, and identify the best candidates to interview.

By adding the Java (Coding) Data Structures test to your pre-employment assessment, you can test candidates on the technical skills needed for the job. You can also add tests that evaluate applicants on soft skills, culture add, and personality to give you an in-depth overview of each candidate’s skills and help you see how they would fit into the role.

In addition, TestGorilla can integrate with leading applicant tracking systems (ATS), enabling you to manage recruitment in one system. This helps you simplify your hiring process without having to ask applicants to create additional accounts to complete the assessments.

Start hiring smarter, faster, and bias-free with TestGorilla today!


Related tests

New test

Android Development Using Kotlin

This Android Development Using Kotlin test evaluates candidates’ ability to develop mobile applications using Kotlin. This screening test will help you hire Android developers who can effectively enhance functionality and tackle development challenges.
10 min

Coding: Data Structures - Heaps

This intermediate-level coding challenge assesses candidates' proficiency in working with heaps, in the programming language of their choice. You can configure which programming languages will be available for your candidates.
35 min

Coding: Data Structures - Hash Tables

This intermediate-level coding challenge assesses candidates' proficiency in working with hash tables, in the programming language of their choice. You can configure which programming languages will be available for your candidates.
35 min
New test

Coding: Data Structures - Binary Search Trees

This intermediate-level coding challenge assesses candidates' proficiency in working with binary search trees, in the programming language of their choice. You can configure which programming languages will be available for your candidates.
35 min


This GraphQL test evaluates a candidate’s ability to effectively work with, create, and maintain GraphQL APIs. This screening test will help you hire developers who can work with GraphQL on both the front and back end.
10 min

Coding: Data Structures - Stacks and Queues

This intermediate-level coding challenge assesses candidates' proficiency in manipulating stacks and queues. You can configure which programming languages will be available for your candidates.
35 min


The Redis test assesses candidates’ skills in using Redis, an in-memory datastore. This test helps you identify developers skilled in using data structures, commands, modules, and other key features of Redis.
10 min


This Blazor test evaluates candidates’ skills in Blazor development, identifying those who can efficiently architect modern web applications, ensuring faster development cycles, reduced maintenance costs, and enhanced user experience.
10 min

Coding: Data Structures - Graphs

This intermediate-level coding challenge assesses candidates' proficiency in graph data structures. You can configure which programming languages will be available for your candidates.
35 min

Coding: Data Structures – Binary Trees

This intermediate-level, language-agnostic coding challenge assesses candidates' proficiency in manipulating binary trees, enabling candidates to choose their preferred programming language. Employers can configure supported languages as needed.
35 min