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Java is a programming language designed exclusively for use in the distributed environment of the Internet. Speed, security and reliability are the major pluses of Java. Complete applications for a single computer or for distribution amongst servers and clients in a network, a small application module or applets, Java can help build them all. In simple terms, Java can be used to develop applications and share them across platforms. The popularity and the necessity of Java can be gauged from the fact that numerous applications and websites will not work without installing Java. Java can safely be called the major force enabling technologies within enterprises.

Therefore, hiring a candidate with proven Java developer skills is an important but difficult proposition. To compound the problem, recruiters and hiring managers may not have worked in Java or don't have any knowledge on Java. A series of programming tests may be the answer to this issue. Then there are core Java interview questions that interviewers may put forth during a face-to-face interview with the candidate to assess his/her knowledge and skills.

Frequently Asked Core Java Interview Questions


Q1. What are the features in JAVA?

Ans: The various features of Java are Inheritance, Object-oriented, Encapsulation, Polymorphism and Abstraction. The features can also be described as platform-independent, High Performance and Multi-threaded.


Q2. What makes Java high performance?

Ans: It uses Just In Time compiler that converts instructions to bytecodes to deliver high performance.


Q3. What are the differences between Serialization and Deserialization in Java?

Ans: Serialization is a process where objects are converted to byte streaming by writing it in ObjectOutputStream. On the other hand, Deserialization is the opposite process where byte stream is converted to objects by reading it from ObjectInputStream.


Q4. Define  SerialVersionUID

Ans: When an object is being serialised, it is stamped with a SerialVersionUID based on the object class. This ID is referred to while verifying if the sender and receiver are compatible with the serialisation.


Q5. What is the Java IDE’s?

Ans: Eclipse and NetBeans are the IDE's of JAVA.


Q6. What do you call the process of defining method in a sub class that has the same name and type signature as a method in its superclass?

  1. a)   Method overriding
  2. b)   Method overloading
  3. c)   Method hiding
  4. d)   None of the above

Ans: a) Method overriding


Q7. What will be the output of the following program?

class Main {

    public static void main(String args[]) {  



    int fun()


      return 20;



  1. a)   Return 20
  2. b)   20
  3. c)   0
  4. d)   Compiler error


  1. d) Compiler error

Explanation: In Java, it is not allowed to call a non-static function inside a static function

Find the Right Developer Skills for Your Organisation with Coding Assessments

If you want to hire a good developer, you will have to forgo a pen-and-paper assessment and go for computer-based coding assessments. The performance of the candidates in the coding assessments will determine their knowledge, skills and capabilities to a large extent. The results will help recruiters select the candidates whom they would like to call for a face-to-face interview. Armed with a list of core Java interview questions, recruiters will find making the right choice of candidates for the job role becomes a breeze. In the case of lateral hiring, recruiters should prepare a list of core Java interview questions for experienced candidates for ready reference. Basically, choosing the right Java assessment that will help measure the relevant coding and programming skills of the candidates is important for efficient recruitment process.

Applications of MeritTrac Assessment Solutions

Recruiters will find MeritTrac’s impressive range of technology-driven assessments quite useful. MeritTrac has assessment solutions not only for recruitment drives but for workforce development as well.  

We have numerous domain assessments to help you measure a wide variety of industry skills and hire candidates suitable to the job role. Our Java coding assessments will help you select the Java programmer and developer with the necessary skills. The results of the Java assessments will help recruiters select the relevant candidates for a face-to-face interview. With a list of core Java interview questions in hand, hiring managers can assess the candidates for their knowledge and skills in core Java. A list of core Java interview questions for experienced candidates will help during lateral hiring.

The learning and development department can make use of MeritTrac’s assessment solutions to gauge the strengths and weaknesses of existing Java team members. They can make use of the performance results to design a training program for workforce development.

MeritTrac Platform for Core Java Programmer Assessment

MeritTrac offers complete support to its clients in their mission to create an efficient workforce. Be it recruitment or workforce development, we have the right assessment solution. From designing the suitable Java test based on your requirement to complete exam administration and the result compilation and analysis at the end of the process, we are there with you at every step.

The assessments are delivered on highly adaptive MeritTrac platforms that are easy to set up and use. Merittrac’s CodeTrac can be used to administer online tests on Java. It is a performance-based coding platform with real-time feedback mechanism that allows recruiters to assess the candidates’ coding skills for performance benchmarking and effective recruitment.

CodeTrac helps companies:

  • Design an efficient developer recruitment cycle
  • Assess skill gaps in the existing workforce
  • Come up with tailor-made coding scenarios to pick the right candidates for the unique business needs
  • Come up with specific setup to suit their pre- and post-training requirements.

Some of the salient features of CodeTrac are given below:

  • Unified assessment platform allows for building, compiling and testing stages
  • The all-inclusive software development feature allows full-stack software development assessment
  • Auto evaluation presents the results quickly
  • With an extensive programming language library, conducting assessments in a wide range of coding languages is possible
  • Candidates are assessed on projects rather than standalone programs which is beneficial to gauge their capabilities in a broader perspective.