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Java is an object-oriented, class-based programming language that is used for developing applications. It was developed by James Gosling, Patrick Naughton, Mike Sheridan and their green team for Sun Microsystems in 1995. Java was then acquired by Oracle Corporation. The original purpose of developing this language was for digital devices such as televisions and set-top boxes.

Currently, the applications created by Java programming language are not just for digital devices, but a host of other services too. Java applications are used in banking, retail, stock market, big data analytics, financial services, information technology, android development and scientific research. Organisations are continually on the lookout for skilled Java programmers for building effective and efficient tools and applications.

Recruiters hiring skilled programmers cannot just rely on traditional recruitment methods based on a resume or Java interview questions to filter out the right talent. Online assessment with Java programming interview questions can help identify candidates with the requisite domain knowledge and expertise from a huge pool of candidates. These assessments will have multiple choice questions, find the output and subjective questions that will help evaluate a candidate’s Java programming expertise. The next section gives you an idea of questions that could be asked in a Java online assessment test.

Basic questions to ask in Java interviews

Are you preparing for a Java technical interview and wondering about the different types of basic Java interview questions you should ask?

Listed below are a few of the most commonly asked questions in your Java interviews:

  1. What is meant by the Local variable and the Instance variable?
  2. What are the differences between Heap and Stack Memory in Java?
  3. Will the program run if we write static public void main?
  4. What is the default value stored in Local Variables?
  5. Why is Java not completely object-oriented?
  6. What happens when the main() isn't declared as static?
  7. What is JDK? Mention the variants of JDK?
  8. What are Brief Access Specifiers and Types of Access Specifiers?
  9. Why is the delete function faster in the linked list than an array?
  10. Briefly explain the concept of constructor overloading
  11. What are the observer and observable classes?
  12. What is the purpose of a Volatile Variable?
  13. How is an infinite loop declared in Java?
  14. Write a Program to remove duplicates in an ArrayList.
  15. Write a program to find the Second Highest number in an ArrayList
  16. Why is Java not a pure object oriented language?
  17. How is Java different from C++?
  18. Pointers are used in C/ C++. Why does Java not make use of pointers?
  19. What are the default values assigned to variables and instances in java?
  20. What do you mean by data encapsulation?

Frequently Asked Java Interview Questions

Java interview questions and assessment tests can include simple algorithmic challenges and coding challenges as well as subjective questions. 

Q1. How to serialise an object in Java?

Ans: In Java, serialisation is used to convert an object to byte stream by implementing an interface named Serializable by the class.

Q2. Find out the output of the following program

class Test  

public static void main (String args[])  

     System.out.println(10 + 20 + "Javatpoint");  

        System.out.println("Javatpoint" + 10 + 20); 

}

Ans: 30Javatpoint and Javatpoint1020

Explanation:

Case 1: 10 and 20 are considered as numbers. Their sum 30 is treated as a string and on concatenation with string Javatpoint, gives output 30Javatpoint.

Case 2: String Javatpoint is concatenated with 10 to form string Javatpoint 10, which on concatenation with 20 results in Javatpoint 1020.

Q3. What is the output of the below program?

class Test  

int test_a, test_b; 

Test(int a, int b)  

test_a = a;  

test_b = b;  

public static void main (String args[])  

     Test test = new Test();  

     System.out.println(test.test_a+" "+test.test_b); 

Ans: Compiler error

Explanation: The call to the default constructor in the main method is not added in the class. Also, the class test has only one parameterized constructor. So, no defaulter constructor is involved by constructor, leading to a compiler error.

Q4. What is the default value of int variable?

  1. Null
  2. 0
  3. 0.0
  4. Not defined

Ans: a. 0

Q5. Choose the correct syntax that can be used for the main method of a Java class?

  1. public static void mainString[]args
  2. public static int mainString[]args
  3. public int mainString[]args
  4. None of the above

Ans: a. public static void mainString[]args

Q6. What do you call the wrapping up of data and functions into a single unit?

  1. Abstraction
  2. Data Hiding
  3. Encapsulation
  4. Polymorphism

Ans: c. Encapsulation

Q7. Choose the right sequence of the major events in the life of an applet?

  1. start, init , stop , destroy
  2. init, start, stop, destroy
  3. destroy, start, init, stop
  4. init, start, destroy

Ans: b. init, start, stop, destroy

8. Which of the following is not a Java features?

  1. Dynamic
  2. Architecture Neutral
  3. Use of pointers
  4. Object-oriented

Ans:Dynamic

9. What is the return type of the hashCode() method in the Object class?

  1. Object
  2. INT
  3. Long
  4. Void

Ans: INT

10. What does the expression float a = 35 / 0 return?

  1. 0
  2. Not a Number
  3. Infinity
  4. Run time exception

Ans: Infinity

11. Which of the following creates a List of 3 visible items and multiple selections abled?

  1. new List(false, 3)
  2. new List(3, true)
  3. new List(true, 3)
  4. new List(3, false)

Ans: new List(3, true)

12. Which of the following is true about the anonymous inner class?

  1. It has only methods
  2. Objects can't be created
  3. It has a fixed class name
  4. It has no class name

Ans: It has no class name

13. Which of these classes are the direct subclasses of the Throwable class?

  1. RuntimeException and Error class
  2. Exception and VirtualMachineError class
  3. Error and Exception class
  4. IOException and VirtualMachineError class

Ans: Error and Exception class

14. What do you mean by chained exceptions in Java?

  1. Exceptions occurred by the VirtualMachineError
  2. An exception caused by other exceptions
  3. Exceptions occur in chains with discarding the debugging information
  4. None of the above

Ans: An exception caused by other exceptions

15. What is the use of the intern() method?

  1. It returns the existing string from memory
  2. It creates a new string in the database
  3. It modifies the existing string in the database
  4. None of the above

Ans: It returns the existing string from memory

16. Out of these statements, which ones are incorrect?

  1. The Brackets () have the highest precedence
  2. The equal to = operator has the lowest precedence
  3. The addition operator + and the subtraction operator – have an equal precedence
  4. The division operator / has comparatively higher precedence as compared to a multiplication operator

Ans: The division operator / has comparatively higher precedence as compared to a multiplication operator

17. Out of these methods of the String class, which one can be used for testing the strings for equality?

  1. isequals()
  2. isequal()
  3. equals()
  4. equal()

Ans: equals()

18. Which of these interface handle sequences?

  1. Set
  2. List
  3. Comparator
  4. Collection

Ans: List

19. Which of this interface must contain a unique element?

  1. Set
  2. List
  3. Comparator
  4. Collection

Ans: Set

20. Which of the following is true about primitives?

  1. You can call methods on a primitive.
  2. You can convert a primitive to a wrapper class object simply by assigning it.
  3. You can convert a wrapper class object to a primitive by calling valueOf().
  4. You can store a primitive directly into an ArrayList.

Ans: You can convert a primitive to a wrapper class object simply by assigning it.

21. How do you force garbage collection to occur at a certain point?

  1. Call System.forceGc()
  2. Call System.gc()
  3. Call System.requireGc()
  4. None of the above

Ans: None of the above

22. What do you mean by >>> operator in Java?

  1. Left Shift Operator
  2. Right Shift Operator
  3. Zero Fill Right Shift
  4. Zero Fill Left Shift

Ans: Zero Fill Right Shift

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Essential Programming Skills to be Evaluated while Hiring Java Programmers

Get the best talent onboard by using the online assessment tests and Java coding interview questions based on the required domain skills and knowledge. The list of the essential coding skills that you should evaluate while hiring Java programmers are:

  • Core Java concepts
  • OOPS concepts
  • Static – keywords
  • Network APIs
  • Garbage collection
  • Multi-threading
  • Lambda expressions
  • Streams
  • Frameworks like Hibernate and Spring
  • JVM Architecture

Apart from these, the candidate should also have hands-on experience on the latest version of the programming language or the version that your project requires. Recruiters can also check to see if the candidates have the relevant certification in Java coding based on the job profile.

Applications of MeritTrac Assessment Solutions

MeritTrac’s online assessment solutions with updated Java programming interview questions can be used for hiring both beginner level and experienced programmers. These online assessments prove useful during campus hiring and walk-ins when hundreds of candidates need to be evaluated in a short span of time. Our assessment solutions can also be customised for lateral hiring for senior positions. When you have a new project that requires Java expertise, you can use these online tests to evaluate the workforce and select the right talent for the new project. Also, these tests help L&D teams identify skill gaps in the workforce, which can help them plan the training program.

MeritTrac Platform for Java Programmer Assessment

MeritTrac offers a simple and effective solution for administering Java programming tests. Our platform CodeTrac is custom-designed to deploy programming tests. MeritTrac has helped administer more than 3 lakh assessments for both hiring and training requirements. The platform is built-in with domain-based online coding tests that are designed by subject-matter experts and experienced programmers. These assessments help recruiters evaluate a candidate’s knowledge in Java programming as well as expertise in coding programs based on language version or project requirements. The salient features of MeritTrac’s coding platform are:

  • Full-stack software development assessment
  • Integrated programming environment
  • Includes a vast library of programming languages
  • Enables project-based testing
  • Consistent coding structure for standardized submissions
  • Auto evaluation

Recruiters who don’t have programming or technical background can also effectively use this user-friendly platform that doesn’t require any installation. The platform authenticates and verifies candidates based on the instructions given. The remote proctoring option ensures that there are no malpractices when the test is being taken. After the test is completed, the tool digitally evaluates the answers and gives you the results. It will also create a rank-based list based on predetermined threshold performance metrics. Based on the analytics reports, recruiters can filter out qualified candidates for the next round of the hiring process.

JAVA Interview Questions

1. What is Java?

Java is a platform-independent, high-performance, multithreaded, and portable high-level, object-oriented, resilient, and secure programming language. It was created in June 1991 by James Gosling. Because it comes with its own JRE and API, it's also known as the platform.

2. What do you understand by Java virtual machine?

A virtual machine that allows a computer to run a Java programme is known as a Java Virtual Machine. The JVM functions as a run-time engine that calls the main method in Java programming. The Java Virtual Machine (JVM) is a specification that must be implemented in a computer system. JVM compiles Java code into Bytecode, which is machine agnostic and similar to native code.

3. What is JIT compiler?

JIT (Just-In-Time) compiler: It is employed in order to enhance performance. JIT compiles bits of the bytecode with similar functionality at the same time, reducing the amount of time it takes to compile. The term "compiler" refers to a translator from a Java virtual machine's (JVM) instruction set to the instruction set of a specific CPU.

4. What are the advantages of Packages in Java?

The benefits of defining packages in Java are numerous.
The package makes it easier to manage access.
We can also have hidden classes that are not accessible outside of the package but are used by it.
It's a lot easier to find the classes that are linked.

5. What are the advantages of Packages in Java?

The benefits of defining packages in Java are numerous.
The package makes it easier to manage access.
We can also have hidden classes that are not accessible outside of the package but are used by it.
It's a lot easier to find the classes that are linked.

6. What is an object?

The Object is a real-time entity that has a state and behaves in some way. In Java, an object is a class instance with instance variables that represent the object's state and methods that represent the object's action. The new keyword can be used to construct a class object.

7. What is the constructor?

The Object is a real-time entity with a state and a set of behaviors. An object in Java is a class instance with instance variables representing the object's state and methods representing the object's actions. A class object can be created with the new keyword.The Object is a real-time entity with a state and a set of behaviors. An object in Java is a class instance with instance variables representing the object's state and methods representing the object's actions. A class object can be created with the new keyword.

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