Every time you apply for a software developer job in a small or big company, you can’t get that job until you thoroughly prepare frequently asked Java Interview questions. In this post, I’m going to highlight ten questions that almost every other recruiter asks when you in an interview for a software development job. The purpose of all these questions is to test your skill and understanding level. Therefore, it is vital to go through those questions and refreshes your concepts before you get ready for your next interview call.

Top 10 Most Commonly Asked Java Interview Questions

The fact is that every interview is unique, and you might encounter tons of questions in just one sitting. But I intend to give you a chance to prepare the best answers in your mind. It’s not possible that your interview contains all the below-mentioned questions. But some of these could be asked by your recruiters, so let’s check them out quickly.

1. What is Java?

It is a programming language used to create applications. This language is designed to offer a feel of C++ programming language. However, it is simple to use and revolves around object-oriented programming model. This language is used to create an application that can be used on a computer, servers, or clients in a network.

2. What is the Difference between JVM, JRE?

JVM stands for Java Virtual Machine, which is an abstract machine that offers a runtime environment where you can execute Java bytecode. Oracle and other companies render the implementation of JVE. This platform-dependent machine is available for various hardware and software platforms. Three notions of the JVM are specification, implementation, and instance. The implementation of JVM is known as JRE.

JRE is an acronym for Java Runtime Environment. It unlocks a set of software tools. Developers used these tools for Java application development.  

3. What is a multi-catch block in Java?

Multi-catch block is available in Java 7; this option makes codes short and clean, especially when every catch block has a similar system. A multi-catch block is one where we can catch multiple exceptions in just one catch block. With the mean of a pipe (|), numerous exceptions can be separated in a catch block.

4. What is the difference between abstract Class and interface?

It is among the commonly asked Java Interview questions. Therefore, you should prepare it right away. A developer can use the abstract keyword for creating abstract Class. Check this tutorial for creating abstract class in Java. In the same manner, the interface keyword let him develop the interface. You can do method implementation in abstract classes, but it’s not possible in interfaces. In a class, you can have only one abstract, but you can extend multiple interfaces in it. If an abstract class has a primary () method, then we can run it, but we can’t run an interface.

5. Where you store Java Compiler? In JDK, JRE or JVM?

A Java compiler converts java program into bytecode with the mean of javac executable. JDK is where we store Java compiler. There is no need to store in JRE, while JVM is nothing but the specifications.

6. What is System class, and how you use it?

It is among the core classes. It is a final class where we can’t have a subclass. Even we can’t override its behavior with the use of inheritance. No public constructors are provided by system class; there we can’t instantiate this Class. Given all those facts, all of the methods in System class are static. Generally, software developer utilizes this Class for some utility methods such as getting the current time, know about environment variables, or having an array copy.

Note: The basic concept of variable and Class is must be on your finger-tips because many recruiters only want to test your idea in the first interview. And therefore, they go with one of the standard Java Interview questions like 

• what is Class?

•  What do you know about the object in Java?

•  How do you define variables?

7.  What is the use of static methods and variables?

All objects of the Class commonly share static methods and variables. Static variables are stored in the Class, and they are part of a class, not an object. There are some variables and methods which are common to all the objects in a class; we can define them through static. For example, there is a class showing the collection of students in a university. The name of the university is common to attribute among all students. So, we can define it via static for that particular Class.

8. What are constructors in Java?

A Constructor means a block of code that a developer typically uses to kickstart with an object. The name of the construct must be similar to that of the Class. Also, it shouldn’t have any return type. In Java, we use two types of constructors. One is named as Default Constructor, while the other is recognized as a Parameterized constructor.

Note: Some other Java interview questions which you should prepare: What is the default constructor? How you use a Parameterized constructor?

9. What is meant by the association in Java?

It describes a relationship where all objects come with their lifestyle, and they don’t have any owner. For example, there is an association between university students and professors. Multiple students take a class of a single professor. In the same way, one student learns from various professors. There is no owner in this specific association. There are different forms of associations, such as one to one, one to many, many to one, or many to many.

Note: When you are going to answer some basic Java Interview questions, make sure you quote some real-life examples to create an extraordinary impression.

10. What is Polymorphism in Java?

It is among the significant building blocks of OOP. Polymorphism is an ability that allows a developer to develop functions of reference variables in a way that they behave differently in a diverse programming context.

Conclusion:

If you want to get success in your software developer interview, then you should duly prepare not only the basic Java Interview questions but also some advanced ones.

Some Useful Links:

Check Common PHP Interview Questions and Answers

Popular JQuery Interview Questions

Simple and Advanced Programming Interview Questions