Java (coding): data structures

Java data structures test: Online screening assessment to hire the best candidates

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.

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.

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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.

java assessment
java assessment

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!


What is the difference between an assessment and a test?
An assessment is the total package of tests and custom questions that you put together to evaluate your candidates. Each individual test within an assessment is designed to test something specific, such as a job skill or language. An assessment can consist of up to 5 tests and 20 custom questions. You can have candidates respond to your custom questions in several ways, such as with a personalized video.
Can I add my own questions to an assessment?
Yes! Custom questions are great for testing candidates in your own unique way. We support the following question types: video, multiple-choice, coding, file upload, and essay. Besides adding your own custom questions, you can also create your own tests.
How do video questions work?
A video question is a specific type of custom question you can add to your assessment. Video questions let you create a question and have your candidates use their webcam to record a video response. This is an excellent way to see how a candidate would conduct themselves in a live interview, and is especially useful for sales and hospitality roles. Some good examples of things to ask for video questions would be "Why do you want to work for our company?" or "Try to sell me an item you have on your desk right now." You can learn more about video questions here.
Can you explain how the other custom question types work?
Besides video questions, you can also add the following types of custom questions: multiple-choice, coding, file upload, and essay. Multiple-choice lets your candidates choose from a list of answers that you provide, coding lets you create a coding problem for them to solve, file upload allows your candidates to upload a file that you request (such as a resume or portfolio), and essay allows an open-ended text response to your question. You can learn more about different custom question types here.
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Yes! You can add your own logo and company color theme to your assessments. This is a great way to leave a positive and lasting brand impression on your candidates.
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Can I combine the Java (coding): data structures test with other tests?
Yes. You can add up to five tests to each assessment.
Where in my recruitment process should I use the Java (coding): data structures test?
We recommend using our assessment software as a pre-screening tool at the beginning of your recruitment process. You can add a link to the assessment in your job post or directly invite candidates by email. TestGorilla replaces traditional CV screening with a much more reliable and efficient process, designed to find the most skilled candidates earlier and faster.
What kind of coding and programming tests does TestGorilla offer?
We offer coding tests for the following languages: Python, JavaScript, PHP, Java, C, C++, C#, and SQL. These tests feature small coding tasks for a candidate to complete. We also offer multiple-choice tests for web and mobile development framework, such as our Angular, React and Django tests.

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