Top 20 Software Developer Interview Questions and Answers


The main responsibility of a software developer is to create computer software to carry out the user’s specific needs. These may include software applications that may be run on different operating systems such as Windows, MacOS, iOS, Linux, or Android OS.

Therefore, the role of a software developer requires a person with adequate knowledge and experience in the major programming language such as Java and C++. Software development companies are always seeking persons with the best expertise and experience.

While looking for the most suitable person for this role, it is important to ask the right questions. Here are the top 20 questions and answers to anticipate from the right candidate.

1. What are the roles of a Software Developer?

This question is very common in interviews as the interviewer wants to assess if you are aware of your roles as a Software Developer.

Tip #1: Review the roles of a system developer at the back of your mind so you can easily answer the question

Tip #2: Be confident while answering and avoid panicking

Sample Answer

The role of a software developer is to research, design, implement, and manage software programs. Software developers also test and evaluate new programs, as well as identifying parts of an existing program that may need modification. Besides, they are tasked with writing and implementation of efficient codes.

2. What is a Singleton Class?

An experienced software developer will always have worked with various types of classes and that is what is being tested here.

Tip #1: Describe briefly what a singleton class is

Tip #2: Be precise on your answer to avoid confusion

Sample Answer

A singleton class is a class whose instantiation is restricted to only a single instance. Therefore, it can only be instantiated once in a program. This is beneficial when only one object is required to coordinate all the actions in a system.

3. What is a Functional Requirement?

The interviewer wants to know if the software developer knows the different types of requirements in software development.

Tip #1: Revise the different requirements in software development at the back of your mind.

Tip #2: Be clear while explaining to convince the interviewer that you know what you are talking about.

Sample Answer

It is the description of the expected specific functionalities of a system. It clearly defines a function of a system, or its components, while describing the function as a behavior specification between the inputs and outputs.

4. Explain What a Non-Functional Requirement is.

The interviewer wants to find out if you are aware of the different types of requirements of a system.

Tip #1: At the back of your mind, revise through the different types of system requirements.

Tip #2: Be clear while giving your answer so that the interviewer can be convinced that you know what you are talking about.

Sample Answer

It is a requirement that specifies the general behavioral requirements of a system. It gives a description of what you expect your system to be, rather than how it should function. The non-functional requirements include accessibility, maintainability, and security.

5. In Object-Oriented Programming, what is Inheritance?

The interviewer wants to know whether you know the concepts of object oriented programming.

Tip #1: Briefly explain what inheritance is.

Tip #2: Make sure to relate your answer to a class as used in Object-Oriented Programming.

Sample Answer

A child class can inherit attributes from a parent class, yet it may extend and/or change parts of it. This makes code reuse easy when classes have common attributes.

6. Describe a Deadlock Situation using threads X and Y, and Resources A and B

Deadlock situations can be quite often in resource allocation of a system, and the interviewer wants to find out if you are aware of its cause.

Tip #1: Have in mind what causes a deadlock to occur

Tip #2: Briefly explain the occurrence of a deadlock using the given threads and resources

Sample Answer

Resource A is reserved by thread X, while resource B is reserved by thread Y. Without releasing resource A, thread X requests for resource B, but have to wait for it to be released by thread Y. At the same time, thread Y requests for resource A without releasing resource B, but has also to wait until it is released by thread X. both threads end up waiting for the release of the resources held by the other, yet none is ready to release until the other does.

7. State the Steps in a Waterfall Method

There are various types of system development methods and the interviewer wants to know whether you know the steps involved in a waterfall method.

Tip #1: Revise the steps involved in the waterfall method at the back of your mind

Tip #2: State them precisely without indulging in explanations

Sample Answer

The waterfall model is a sequential software development process in which progress is viewed as a steady downward flow like in a waterfall, passing through various phases such as Conception, Initiation, Analysis, Design, Construction, Testing, Implementation, and Maintenance.

8. What’s the Use of a Sequence Diagram/ Event Diagram?

Sequence diagrams give an overview of an application’s flow in a runtime, and the interviewer wants to know whether you are aware of what they are, and their purpose.

Tip #1: Explain the purpose of a sequence diagram

Tip #2: Be precise and direct to the point

Sample Answer

A sequence/event diagram shows the interactions, messages sent, and values returned between objects and the order in which they are sent. This provides an overview of the runtime flow of the system.

9. What’s the Aim of the Daily Stand-Up Meeting In Agile Software Development?

Scrums are very crucial in agile software development, and the interviewer wants to know whether you are aware of their purpose and importance.

Tip #1: Briefly explain the importance of the daily stand-up meetings

Tip #2: Be precise and straight to the point to be convincing to the interviewer.

Sample Answer

The daily stand-up meetings aim at keeping the team up to the speed as they describe what they have done so far, and what they plan on doing next, as well as any real or potential hindrances to their progress. The stand-up meeting works in such a way that each member of the team addresses the following three parts one after the other: 1.) What I did yesterday, 2.) What I will do today, 3.) What impediments I have discovered that may hinder our progress

10. What are the Pros and Cons of Paper Prototyping?

Paper prototyping is very crucial in system development, and the interviewer wants to know whether you are aware of the advantages and disadvantages of paper prototyping.

Tip #1: Briefly state the advantages and disadvantages of paper prototyping

Tip #2: Be clear and precise with your answer

Sample Answer

The main advantage of paper prototyping is that it is fast and relatively cheap. It also allows the whole team to easily participate in the design process.

The major disadvantage of paper prototyping is that it does not emulate the actual feeling of a system and some specific functionality, such as scrolling, data entry, and dynamic elements. The paper prototypes are only capable of showing the general outline and a few specific functionalities of the system.

11. Explain the Meaning of Modularization

The interviewer wants to know whether you know the purpose of modularization is, especially when it comes to maintenance of a system.

Tip #1: Explain briefly what modularization is.

Tip #2: Be direct to the point.

Sample Answer

This is the technique whereby software is subdivided into modules that can work without depending on each other. This makes the maintenance of the system easier.

12. Describe the Model-View-Controller Architecture.

This question prompts you to describe the MVC architecture, and the interviewer can easily deduce whether or not you are familiar with the different interface model architectures.

Tip #1: Be brief while giving the description

Tip #2: Be straight to the point

Sample Answer

The MVC architecture is widely used in GUI applications and implies separating data from the user interface. Data is held by the model layer, while the view layer outputs the processed data for the user, and the necessary changes are made to the model by the controller based on user output.

13. Describe what a Directed Acyclic Graph is.

Through this question, the interviewer seeks to know whether you understand what a DAG is.

Tip #1: Be precise while explaining what a DAG is.

Tip #2: be convincing to the interviewer by avoiding long explanations that may bring confusion in your explanation.

Sample Answer

A DAG is a finite directed graph (the edges have direction) that has no directed cycles. It depicts the assumptions of the relationship between variables (nodes) in the form of lines (edges) that join the nodes.

14. What is the Difference Between a Queue and a Stack?

Both the queue and the stack are both used in the execution of system jobs, yet they work differently. The interviewer wants to know what you understand how they both work.

Tip #1: State the principles that they are based on.

Tip #2: Be clear and straight to the point.

Sample Answer

A queue is based on the First In First Out (FIFO) principle which implies that the items that are first to enter the queue will be the first to be removed, while on the contrary, a stack is based on Last In First Out principle (LIFO) which implies that the last item to enter into the stack will be the first on to be removed.

15. What is a Recursive Function?

The aim of this question is for the interviewer to find out whether you understand the various types of functions.

Tip #1: Briefly explain what a recursive function is

Tip #2: Give the impression that you know what you are talking about

Sample Answer

A recursive function is a function that does not necessarily require to be called, but rather calls itself. In each call of the function, at least one parameter is changed. The recursion may continue until a base case is reached, and the recursion is resolved.

16. Explain the difference between Black Box and White Box Testing?

The interviewer seeks to know whether you are aware of the different types of testing methods.

Tip #1: Avoid mulling as it may cause question on the answer that you give

Tip #2: Be confident while giving your answer

Sample Answer

Black box testing only tests for the correct output of a function, given an input. On the other hand, white box testing tests for a correct implementation.

17. Describe Your Daily Routine as a Software Developer

The interviewer wants to know whether you understand the daily duties of a software developer.

Tip #1: Mention the duties that may be expected of you

Tip #2: Keep your answer straight to the point.

Sample Answer

My duties would include coding, researching new coding methods, identifying and fixing software bugs, and system testing. Besides, I would create documentation for new software and monitor them to ensure they are operating optimally and in conformance with specifications.

18. What Does Inner and Outer Join Do In Sql Using Unique Keys?

This question aims at finding out whether you are aware of the operations of an SQL database.

Tip #1: Demonstrate your knowledge in SQL database

Tip #2: Be clear while giving your answer

Sample Answer

The two operations are used in joining two tables. The inner join intersects between the tables, thus only the keys that exist in the two tables that will be kept in the joined table. The outer join functions as the union between the two tables, thus all rows are included in the joined table.

19. How Does the A* Algorithm Work?

The interviewer seeks to know whether you are conversant with the working of algorithms.

Tip #1: Demonstrate your familiarity with algorithms

Tip #2: Be clear while giving your answer

Sample Answer

A* is a path-finding algorithm that works on weighted graphs with a heuristic function that estimates the cost of travelling from node n to the goal node. The nodes considered in each step are stored in a priority queue. At the start, it adds every adjacent node to the start node into the queue with the estimated total cost, based on the formula f(n)=g(n)+h(n), where g(n) is the actual cost from the start node to node n, while h(n) is the heuristic function. In each iteration, the node with the least estimated cost f(n) is expanded. A path is only found when the goal node is the one chosen for expansion. But if the queue becomes empty, no path is chosen.

20. Explain What an SQL Injection is, and How to Prevent It

In this question, the interviewer wants to find out if you know how to solve SQL related problems.

Tip #1: Ensure that you are confident enough while answering

Tip #2: Avoid mulling

Sample Answer

An SQL injection means the entering of SQL statements into data fields stored in an SQL database. They are prevented by use of techniques such as parameterized statements, escaping characters with special meaning in SQL, checking patterns, and database permissions limitation.

Conclusion

Before walking into an interview, it is important to take some time to learn as much as possible. This includes understanding the common questions and the right answers. This improves the chances of landing the job since you can customize your answers according to what the interviewer is looking for.

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