Top Java Interview Questions

In the initial interview, the hiring managers evaluate candidates’ fundamental concepts of Java Programming language. As the discussion between interviewers and interviewee progresses, the candidate may require to discuss particular details about the subject.

 To qualify the interview, you need to be well-versed in the basic concepts of Java. You may expect the following questions during your interview for Java programming. The paper also provides answers to the questions. Try to be precise and concise while answering the questions.

Java Interview Questions

Following are the common Java interview Questions:

1. Express your knowledge about Java?

Java is an advanced programming language; Sun Microsystems are the pioneers of this language developed in 1995. Java uses several platforms like MAC Operating Systems, Windows, and different types of UNIX. 

2. Name any Five Features of Java?

Java is a dynamic programming language. Some of its main features are Object Oriented, Multi-threaded, System compatible, Platform Independent, and Interpreted. 

3. What makes Java Architectural Neutral?

The compiler of Java creates the architecture-neutral object file type. As a result, the compiled code can execute on several processors through the Java runtime system. 

4. How Java gives High Performance?

Java employs a Just-In-Time compiler that is high-performing. This complier serves as a system that leads to Java bytecode. It carries instructions that require decoding so that processor can directly receive them. 

5. What makes Java a Dynamic Language?

The purpose of designing Java was to adapt to modern trends. Java programs tend to carry a huge amount of runtime data. The users can resolve access to objects during runtime. 

6. Tell us About the Concept of Virtual Machine from Java’s platform perspective?

The compilation does not occur in the platform-specific machine, instead of in the platform-independent bytecode. Subsequently, the bytecode spreads across the web, and Virtual machine (JVM) decodes it irrespective of the platform. 

7. What are the two Java IDEs?

Eclipse, Netbeans, and others. 

8. What are some of the Java Keywords (other than C++, C keywords)?

A few Java keywords are super, import, finally, and others. 

9. What does Object mean?

Object refers to the runtime unit, and fields store its form, and behaviour and displays them through methods. Methods function on the internal form of the item and work as the core system for Object to object communication. 

10. What is the Concept of Class?

The class is a basic layout which helps the creation of individual objects. The class may comprise methods and fields to interpret the behaviour of the Object. 

11. What Type of Variables Can a Class Have?

The class comprises instance variables, Local variable, and class variables. 

12. How Do You Define a Local Variable?

The variables that are defined within methods, blocks or constructors are the local variables. The system initializes and declares variable inside the method and removes that once the process is complete. 

13. How Do You Define Instance Variable?

These are variables inside a class and outside the method. These variables get representation during class loading. 

14. What is a Class Variable?

The variables inside the class, but outside the method are class variables. A static keyword defines these variables. 

15. What Is the Concept of Singleton Class?

Singleton class is in charge of object formation, and it restricts the number to 1. Also, it gives the flexibility to make more objects according to the situation. 

16. What is the concept of Constructor?

Constructor comes into play after the creation of the new Object. Every class is with a constructor. If a user does not explicitly mention a constructor for a class, the java compiler creates a default constructor for such class. 

17. What Are the Three Steps for Object Creation of a Class?

The first step is the declaration of the Object, the next step is instantiation, followed by the initialization. 

18. Do You Know What the Default Value of the Byte Data Type Is?

“0” is the default value of byte datatype.

19. Tell us about the default value of double data type and float in Java?

The default value of double data type and float are not the same. The double data type has a default value 0.0d, and the default value for float is 0.0f.

20. What Is the Use of Byte Datatype?

The purpose of the byte data type is to store space in large arrays; in fact, a byte is four-times smaller than the int. 

21. Define a Static Variable?

Class variables are also the static variables; a static keyword defines them in a class, but out of a method, block or a constructor. 

22. How Do You Define Access Modifier?

Java allows Access Modifiers to adjust access stages for variables, classes, constructors, and methods. A member has default access when there is no specification of Access Modifier. 

23. Define the Concept of Protected Access Modifier?

Methods, constructors, and Variables that are stored in a superclass can only be accessible by the subclass in a different package or any class inside the package of a protected class of members. 

24. What Is the Concept of Synchronized Non-access Modifier?

Java enables these modifiers to function more than the Access Modifiers. The term synchronized refers to the method accessible by a thread at a single time. 

25. From the Perspective of Java Operator Precedence, Which Operator Has the Highest Precedence?

Postfix operators, i.e., () [] hold the highest precedence. 

26. Which Datatypes Can Be Used with the Variables in the Switch Statement?

Variables of a switch statement are just a string, byte, enum, short, char, or int. 

27. What Is the Use of Parseint () Method?

The purpose of this method is to obtain a primitive data type of a particular String. 

28. What Is the Concept of Immutable String Class?

No one can change the String Object after its creation, and that is why the String class is immutable. Due to this particular feature of String, several threads can share it, and it is vital in case of multithreaded programming. 

29. What is the Concept of Exception?

The Exception refers to a problem, which occurs at the time of program execution. The handlers intercept the exceptions as their position is alongside the innovation stack of the thread’s method. 

Final Word 

The article discusses the common questions that are part of many Java interviews. To make an impression in the interview for Java programming, you need to demonstrate vital basic concepts. Also, good presentation skills will enable you to explain Java programming features.