Interview Questions for a Java Developer

Interview Questions for a Java Developer

Interview questions for a Java developer are different from those for a programmer specializing in another language.

Once you have sent your CV for the vacancy you want, and you have already had the first interviews, a definitive stage arrives: the technical interview .

Starting because each programming language has its own syntax, furthermore, problem solving can be done in many ways, and it is the recruiter’s job to analyze the candidate’s way of working.

Here we show you some of the most frequent questions that are asked to a Java developer , their possible answers and some tips so that you arrive full of confidence to your next stage of recruitment.

What is object-oriented programming?

Object Oriented Programming (OOP) is a programming model that works with the concepts of classes and objects. This model is used to structure software programs into simple, reusable pieces or classes, so that individual instances of objects are created.

This paradigm stops proposing a logic for programs and focuses on the creation of objects.

What is an object?

It is defined as an instance of a class. The object can have a state and a behavior. It is created with “new()”.

What is a class?

Within a class the data and the code that acts on them are defined, therefore, by defining the nature of an object, the classes with the base on which they are built and define the elements to create the entire program.

What are the 4 pillars of object-oriented programming?

  • Polymorphism
  • Abstraction
  • Inheritance
  • encapsulation

What is inheritance?

Inheritance indicates that one class can extend another class, so that the code can be reused in the next class. The class that extends your code is known as a superclass; the class that inherits the code for reuse is called a subclass.

What is abstraction?

Abstraction occurs when the essential data of an object is selected to be displayed, and hides other elements that are less relevant to the use that is being given to the object.

What is polymorphism?

Polymorphism is the ability of an object to have a different shape depending on how it is called in code.

What is encapsulation?

It is to maintain the security of the code, protecting the objects and hiding their attributes. It is common to encapsulate classes, and that information can only be accessed by operations defined during their encapsulation.

Why is Java portable and independent?

It is portable because the code can be read on any device or machine and at the same time it is independent, because it does not need a specific operating system or modifications to be executed. It has its own build platform.

How many types of variables are there in Java?’

local variables

They are the variables defined inside a block, method or constructor.

Instance Variables

They are non-static variables that are declared outside of any block, method, or constructor.

Static variables

They are also known as class variables and are declared using “static”. You can only have one copy of these per class.

What are the differences between vectors and matrices?

Arrays are static so they have fixed and defined sizes and types. Vectors, on the other hand, are dynamically assigned, and contain dynamic lists of references to other objects.

These may be very basic theory questions in the application of the Java language, but there are other questions that could be asked to get to know your way of working, such as the following:


  • From what approach would you solve a given problem?
  • Why would you do it this way?
  • What would be your reaction if at a certain moment someone criticizes your way of working?
  • How would you resolve an error in code? They might give you some options here.
  • How would you resolve a situation in which your way of working was correct and your colleagues proposed another?

These are just a few of the questions IT recruiters can ask Java developers, but once you’ve got your technical skills in place, all you have to do is work on how you collaborate with others.

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