Sunday, July 21, 2024

Java Full Stack Developer Interview Questions

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How Null Is Different From Undefined In Javascript

Full stack developer interview questions and answers – Part 1 | ARC Tutorials

Null: Null means a variable is assigned with a null value. If we use it with typeof operator it gives result as an object. We should never assign a variable to null because the programmer uses it to represent a variable that has no value. Note that JavaScript will never automatically assign the value to null.

Undefined: Undefined means the variable is declared but not assigned any value to it. It may be a variable itself does not exist. If we use it with typeof operator it gives the result undefined. It is not valid in JSON.

Note: Null and undefined both are primitive.

Let’s understand it through an example.

When we execute the above code, it generates the following output:

From the above output, we can observe that the value of var1 is undefined also its type is undefined. Because we have not assigned any value to the variable var1. The value null is assigned to the variable var2. It prints its type as abject. Since null is an assignment value and we can assign it to a variable. Therefore, JavaScript treats null and undefined relatively equally because both represent an empty value.

What Are The Main Differences Between Graphql And Rest

Here are the main differences between GraphQL and REST:

  • REST is an architectural style that places a set of constraints on how web applications are built. GraphQL is a server-side technology used to obtain data by executing queries.
  • REST is executed using a series of endpoints whereas GraphQL takes the form of a schema.
  • GraphQL mutations need to be in the string message format. There are no restrictions on the message format for REST mutations.

What Do You Mean By Observer Pattern

If several objects are tied together in one-to-many relationships, the observer pattern is used. Every time one object is modified, then all of its dependent objects are automatically notified and updated. It falls under the behavioural pattern category. It describes the coupling between the objects and the observer and provides support for broadcast-type communication. The object that observes the state of another object is known as the observer, and the object that is being observed is known as the subject as shown below:

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Java Developer Interview Questions

In some respects even the most technical role demands qualities common to strong candidates for all positions: the willingness to learn qualified skills passion for the job.

Even college performance, while it helps you to assess formal education, doesnt give a complete picture. This is not to underplay the importance of a solid background in computer science. Some things to look for:

Understanding of basic algorithmic concepts Discuss basic algorithms, how would they find/think/sort Can they show a wider understanding of databases? Do they have an approach to modelling?

Do they stay up to date with the latest developments? If so, how? Probe for their favourite technical books. Who are they following on Twitter, which blogs do they turn to?

Are they active on Github? Do they contribute to any open source software projects? Or take part in Hackathons. In short, how strong is their intellectual interest in their chosen field? How is this demonstrated? Ask for side projects . Committed, inquisitive candidates will stand out.

Q8 What Purpose Do The Keywords Final Finally And Finalize Fulfill

Full Stack Java Developer: Role, Career Opportunities and Salary


Final is used to apply restrictions on class, method, and variable. A final class cant be inherited, final method cant be overridden and final variable value cant be changed. Lets take a look at the example below to understand it better.

class FinalVarExample 


Finally is used to place important code, it will be executed whether the exception is handled or not. Lets take a look at the example below to understand it better.

class FinallyExample catch finally }}}


Finalize is used to perform clean up processing just before the object is garbage collected. Lets take a look at the example below to understand it better.

class FinalizeExample public static void main}

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Q44 What Is A Map In Java

In Java, Map is an interface of Util package which maps unique keys to values. The Map interface is not a subset of the main Collection interface and thus it behaves little different from the other collection types. Below are a few of the characteristics of Map interface:

  • Map doesnt contain duplicate keys.
  • Each key can map at max one value.

  • Q7 Can You Explain The Java Thread Lifecycle

    The java thread lifecycle has the following states-


    When a thread is created, and before the program starts the thread, it is in the new state. It is also referred to as a born thread.


    When a thread is started, it is in the Runnable state. In this state, the thread is executing its task.


    Sometimes, a thread goes to the waiting state, where it remains idle because another thread is executing. When the other thread has finished, the waiting thread again comes into the running state.

    Timed Waiting

    In timed waiting, the thread goes to waiting state. But, it remains in waiting state for only a specified interval of time after which it starts executing.It remains waiting either till the time interval ends or till the other thread has finished.


    A thread is said to be in this state once it terminates. It may be because the thread has completed its task or due to any other reason.

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    Q16 What Are The Latest Trends In Full Stack Web Development

    Ans According to industry experts, a candidate who is passionate about full-stack development should be aware of the following trends:

  • The rise of Vue JS Functional, real-time web apps, progressive apps, and mobile web development.
  • Programming benefits from JavaScript improvements
  • The emergence of more compatible extensions.
  • Q9 What Are Some Of The Important Spring Annotations Which You Have Used

    Full Stack Developer Interview Questions 2022 | Web Development Interview Questions | Simplilearn

    Some of the Spring annotations that I have used in my project are:

    @Controller for controller classes in Spring MVC project.

    @RequestMapping for configuring URI mapping in controller handler methods. This is a very important annotation, so you should go through Spring MVC RequestMapping Annotation Examples

    @ResponseBody for sending Object as response, usually for sending XML or JSON data as response.

    @PathVariable for mapping dynamic values from the URI to handler method arguments.

    @Autowired for autowiring dependencies in spring beans.

    @Qualifier with @Autowired annotation to avoid confusion when multiple instances of bean type is present.

    @Service for service classes.

    @Scope for configuring the scope of the spring bean.

    @Configuration, @ComponentScan and @Bean for java based configurations.

    AspectJ annotations for configuring aspects and advices , @Aspect, @Before, @After, @Around, @Pointcut, etc.

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    Explain Event Loop In Nodejs

    The event loop in JavaScript enables asynchronous programming. With JS, every operation takes place on a single thread, but through smart data structures, we can create the illusion of multi-threading. With the Event Loop, any async work is handled by a queue and listener. Consider the diagram below:

    Therefore, when an async function needs to be executed, the main thread relays it to another thread, allowing v8 to continue processing or running its code. In the event loop, there are different phases, like pending callbacks, closing callbacks, timers, idle or preparing, polling, and checking, with different FIFO queues.

    Guide To Interviewing: How To Screen Java Developer Skills

    A team is a core of any software project. Are you, as the employer, just giving lip service to this concept or affirming these words indeed? Surely, you would like to have the best developers in your team. You will have a job to find the right candidates. This calls for strong interviewing and recruiting competencies. Lets figure out how to screen Java developer skills not to be sorry about your choice.

    First off, you should think about a comprehensive and accurate job description that will communicate your Java project goals to potential employees. So, a good job description must contain the following points:

    • Some words about the companys culture

    These are just main aspects you should definitely include into your description to avoid initial misunderstanding and a bunch of irrelevant CVs sent to you.

    You might be interested in reading about Java outsourcing companies

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    Are You Planning To Be A Full Stack Developer

    With so many firms vying for the finest engineers, finding the right talent in the IT industry is difficult. And knowing who your fellow applicants are and asking proper questions during the interview are essential to stand out as good developers.

    Let’s get started on all you need to know about cracking interviews for full-stack development jobs. This blog guides you with full stack developer job interview questions and answers.

    Backend Frontend Development Skills

    Full Stack Java Developer Required

    Backend development knowledge is the remaining knowledge that defines a developer as fully stacked. Competency in programming languages such as those below are key full stack developer skills:

    5. Web Architecture

    Web architecture knowledge is key for full-stack developers. Understanding how the structure of a website is constructed and utilized allows websites to respond to demand and makes it easier to integrate new functionalities.

    6. Database Management Systems

    Database Management Systems are essentially computerized data management systems. Full-stack developers write code that performs relational mapping to fetch data from the database.

    7. Design Fundamentals

    This is an area where you can really show your versatility with working knowledge of the fundamentals of web design, youre showing your eye for detail at the service user end as well as the technical backend code side of things.

    8. REST and SOAP

    Knowledge of these web service communication protocols is key to showing you up-to-date with web development.

    The original approach to web interface, SOAP , has been taken over by REST , with the latter now representing over 70% of public APIs .

    9. HTTP and Rest

    Knowing the difference between HTTP and REST could set you apart from the rest while the two terms are used interchangeably, HTTP is a well-defined protocol that exhibits REST features.

    10. NPM

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    What Keeps You Motivated

    To prepare for this question, reflect on your own motivations, especially those related to previous projects and work experience. What gave you the greatest sense of accomplishment? What kind of experiences do you try to have again and again? Here are some of the things that commonly drive professionals:

    • Working on big, important projects
    • Helping a company outdo its targets
    • Learning new things

    What Approaches Do You Use For Website Optimization To Ensure Maximum Scalability And Efficiency

    The interviewer will want to know how you apply your problem-solving and critical thinking skills to ensure optimum performance of the applications you develop. Use examples from your past experience to describe your process for optimizing and monitoring a website’s performance.

    Example:There are many different approaches to optimizing a website for maximum scalability. Several approaches I immediately take for this process include placing all of the assets in separate, cookie-free domains using a CDN, avoiding inline JavaScript and CSS, enabling gzipping and reducing the number of HTTP requests to load only necessary external resources.

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    Q8 How To Handle Exceptions In Spring Mvc Framework

    Spring MVC Framework provides the following ways to help us achieving robust exception handling.

    Controller Based:

    We can define exception handler methods in our controller classes. All we need is to annotate these methods with @ExceptionHandler annotation.

    Global Exception Handler:

    Exception Handling is a cross-cutting concern and Spring provides @ControllerAdvice annotation that we can use with any class to define our global exception handler.

    HandlerExceptionResolver implementation:

    For generic exceptions, most of the times we serve static pages. Spring Framework provides HandlerExceptionResolver interface that we can implement to create global exception handler. The reason behind this additional way to define global exception handler is that Spring framework also provides default implementation classes that we can define in our spring bean configuration file to get spring framework exception handling benefits.

    Q1 What Is Polymorphism

    Cognizant | Full Stack Developer | Real-time Java Interview Series | interview 28

    Polymorphism is briefly described as one interface, many implementations. Polymorphism is a characteristic of being able to assign a different meaning or usage to something in different contexts specifically, to allow an entity such as a variable, a function, or an object to have more than one form. There are two types of polymorphism:

  • Compile time polymorphism
  • Run time polymorphism
  • Compile time polymorphism is method overloading whereas Runtime time polymorphism is done using inheritance and interface.

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    Give An Example Of A Poorly

    Questions related to coding practice and architecture help determine the knowledge of a Java developer in the field. As an interviewer, you will notice an experienced developer if they can recall apps they encountered that are terribly developed.

    Candidates who fail to name one may not have dealt with failure. This may be a sign of inexperience, or they may have only worked with exceptional teams. However, a Java developer must know what a good and bad application is.

    The applicant may start by mentioning how the faulty UI or poor coding practice led to a bad user experience or how poor code documentation and organization led to a nightmare code base. If the applicant is more enthusiastic, they may explain how the application may be improved.

    Ques 8 What Is Callback Hell

    It is a must to know about callback hell when appearing for java full stack interview questions and answers. Most interviewers ask this as one of the first questions.

    Ans. The asynchronous function demands callbacks as a return parameter. However, when multiple asynchronous functions get clubbed together, it results in a callback hell situation.

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    Java Full Stack Interview Questions For Preparation

    Do you like developing web apps? If yes, you can consider applying for the role of a full-stack Java developer. Just make sure to prep well for java full stack developer interview questions well in advance.

    A full stack web developer employs Java, a prominent computer programming language, and holds extensive expertise and knowledge in full stack frameworks and tools that work with Java. They can take care of both server and client end needs. They write the code in the triple layers of the web-based apps the database layer, the frontend, and the backend. Their technology suite comprises core java, working with servlets, REST API, and several tools that make app development seamless. It is an excellent career choice.

    The best plausible way to be a Java full stack developer is by working with a tech giant. For this, you have to appear for an interview. The questions you find in the interview may be tough and challenging.

    To help you ace that interview, we will discuss some top-asked java full stack interview questions.

    Faqs On Full Stack Developer Interview Questions


    1. Why are Full Stack Developers in demand?

    Full stack developers are in high demand across the tech industry due to their vast knowledge and versatility. Full stack developer interview questions are designed to choose the most skilled candidates who can work in various divisions.

    Their deep understanding of technical concepts enables them to cope with challenging environments. They prove valuable assets for both budding startups and thriving organizations.

    2. What skills are required to crack full stack developer interview questions?

    Full stack developer interview questions are aimed at analyzing your frontend and backend coding abilities. Interviewers seek whether you are adept in designing user interfaces on websites, developing servers and databases for website functionality, and implementing codes for mobile platforms or not.

    3. Is a Java developer a full stack developer?

    They can be. Full stack development includes simultaneously developing the frontend and backend of web applications. A web developer who uses Java to develop the entire technology stack is called a Java full stack developer.

    4. What skills do I need to crack full stack developer interview questions?

    Competency in HTML, CSS, SQL, etc. expertise in Front-end Frameworks like BootStrap and AngularJS experience in Backend Frameworks like NodeJS and Django proficiency in databases knowledge of Git, Machine Learning, SSH, Data Structures, Linux Command, Character encoding.

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    How To Prepare For A Full

    Research and preparation are key if you want to ace your interview. full-stack developer skills are very diverse and youll need a thorough understanding of all aspects of the role. As the demand for such skilled developers is high, the competition will be tough. Were here to help you fulfill your potential.

    Remember that you have to fit the company as much as the company fits you. Do the research, be true to yourself and be confident that the job and work culture is right for you.

    Most companies wont be seeking 100% perfection but at the very least someone ready to hit the ground running. Make sure you give yourself every edge over other candidates that you can.

    Common Full Stack Web Developer Interview Questions And Answers

    There are always some full stack web developer interview questions and answers that would be very common to ask. And to make this post exhaustive in order to give the maximum benefit to the user, we have researched them as well. Here are the top commonly asked full stack web developer interview questions.

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    What Is A Continuous Integration And Continuous Delivery

    CI/CD is a best practice to develop applications in which code changes more frequently and rapidly. Sometimes, it is also known as CI\CD pipeline. It is widely used in DevOps and also an agile methodology.

    Continuous integration is a coding philosophy or deployment practice in which developers integrate their code in a shared repository several times a day. Because modern application requires developing code in different platforms. The goal of continuous integration is to establish an automated mechanism that builds, test, and package the application.

    Continuous delivery starts where CI ends. It automatically delivers the application to the selected infrastructure. CD ensures the automated delivery of code if any changes are made in the code.

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