3i Infotech Associate Engineer Interview Questions and Answers

Round duration - 60 Minutes
Round difficulty - Medium

In this round, I was first asked about the projects that I worked on in my previous company. I was also asked about the various tech stacks that I was familiar with and then the interviewer started asking me questions around Java and some basic OOPS concepts.

Q1. What are the advantages of using Packages in Java?
Ans. 
Packages in Java help organize code, prevent naming conflicts, and provide access control.
• Organizes code into logical groups for easier maintenance and readability

• Prevents naming conflicts by allowing classes with the same name to coexist in different packages

• Provides access control by using access modifiers like public, private, protected, and default

• Facilitates reusability by allowing classes in one package to be acc...read more
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Q2. Why is Java considered platform independent, while the Java Virtual Machine (JVM) is platform dependent?
Ans. 
Java is platform independent because it compiles code into bytecode that can run on any system with a JVM, which is platform dependent.
• Java code is compiled into bytecode, which is platform independent

• The JVM interprets the bytecode and translates it into machine code specific to the underlying platform

• This allows Java programs to run on any system with a JVM installed, making Java platform independent
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Q3. Why are Java Strings immutable in nature?
Ans. 
Java Strings are immutable to ensure thread safety, security, and optimization.
• Immutable strings prevent accidental changes, ensuring data integrity.

• String pool optimization reduces memory usage by reusing common strings.

• Thread safety is guaranteed as strings cannot be modified concurrently.

• Security is enhanced as sensitive information cannot be altered once set.
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Q4. What do you know about the JIT compiler?
Ans. 
JIT compiler stands for Just-In-Time compiler, which compiles code during runtime instead of ahead of time.
• JIT compiler improves performance by compiling code on-the-fly as it is needed

• It can optimize code based on runtime conditions and platform specifics

• Examples include Java's HotSpot JIT compiler and .NET's RyuJIT compiler
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Q5. Can you differentiate between ArrayList and Vector in Java?
Ans. 
ArrayList is non-synchronized and faster, while Vector is synchronized and slower.
• ArrayList is not synchronized, while Vector is synchronized.

• ArrayList is faster than Vector due to lack of synchronization.

• Vector is thread-safe, while ArrayList is not.

• Example: ArrayList<String> list = new ArrayList<>(); Vector<String> vector = new Vector<>();
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Round duration - 60 Minutes
Round difficulty - Medium

This round had questions revolving around OOPS , Spring Boot and Docker. The questions were preety decent and standard and can be answered if one has prior experience in the given tech stack.

Q1. Can you explain the SOLID principles in Object-Oriented Design?
Ans. 
SOLID principles are a set of five design principles in object-oriented programming to make software designs more understandable, flexible, and maintainable.
• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable...read more
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Q2. What is the garbage collector in Java?
Ans. 
Garbage collector in Java is a built-in mechanism that automatically manages memory by reclaiming unused objects.
• Garbage collector runs in the background to identify and remove objects that are no longer needed.

• It helps prevent memory leaks and optimize memory usage.

• Examples of garbage collectors in Java include Serial, Parallel, CMS, and G1.
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Q3. What does the @SpringBootApplication annotation do internally?
Ans. 
The @SpringBootApplication annotation is used to mark a class as a Spring Boot application.
• It combines @Configuration, @EnableAutoConfiguration, and @ComponentScan annotations.

• It enables the auto-configuration feature of Spring Boot.

• It starts the Spring application context, which is the core of the Spring Framework.

• It scans the current package and its sub-packages for components to register.

• It serves as the entry point...read more
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Q4. What is dependency injection?
Ans. 
Dependency injection is a design pattern where components are provided with their dependencies rather than creating them internally.
• Allows for easier testing by providing mock dependencies

• Promotes loose coupling between components

• Improves code reusability and maintainability

• Examples: Constructor injection, Setter injection, Interface injection
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Q5. What are the basic annotations that Spring Boot offers?
Ans. 
Spring Boot offers basic annotations for various functionalities like mapping requests, handling exceptions, defining beans, etc.
• 1. @RestController - Used to define RESTful web services.

• 2. @RequestMapping - Maps HTTP requests to handler methods.

• 3. @Autowired - Injects dependencies into a Spring bean.

• 4. @Component - Indicates a class is a Spring component.

• 5. @Service - Indicates a class is a service component.

• 6. @Reposi...read more
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Q6. What are the most commonly used instructions in a Dockerfile?
Ans. 
The most commonly used instructions in a Dockerfile include FROM, RUN, COPY, and CMD.
• FROM: Specifies the base image for the container

• RUN: Executes commands in the container

• COPY: Copies files and directories from the host to the container

• CMD: Specifies the default command to run when the container starts
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Q7. What command can be run to import a pre-exported Docker image into another Docker host?
Ans. 
The command to import a pre-exported Docker image into another Docker host is 'docker load'
• Use the 'docker load' command followed by the file path of the exported image tarball to import it into the Docker host

• For example, 'docker load < my_image.tar.gz' will import the image from the file 'my_image.tar.gz'

• Ensure that you have the necessary permissions to access the file and import images on the target Docker host
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Q8. Can you describe the lifecycle of a Docker container?
Ans. 
The lifecycle of a Docker container involves creation, running, pausing, restarting, and stopping.
• 1. Creation: A Docker container is created from a Docker image using the 'docker run' command.

• 2. Running: The container is started and runs the specified application or service.

• 3. Pausing: The container can be paused using the 'docker pause' command, which temporarily halts its processes.

• 4. Restarting: The container can be...read more
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Round duration - 30 Minutes
Round difficulty - Easy

This was a Technical Cum HR round where I was first asked some basic Java related concepts and then we discussed
about my expectations from the company , learnings and growth in the forthcomig years. I would suggest be honest and
try to communicate your thoughts properly in these type of rounds to maximise your chances of getting selected.