15 Technical Core Java Interview Questions Answers for Experienced Developers

When the experience of a Java Programmer grows in the years e.g. when it goes from beginner years ( 2 to 4) to more experience or sort of senior level ( 5 to 7 years), Core Java Interview Questions also change a bit. Of course, basics like data structure, algorithms, and object-oriented programming remains the same, but types of questions will become more advanced and their answers will definitely need to be more detailed and accurate. I often receive queries about core Java questions asked to a senior developer with 5 to 6-year experience, or, sometimes, I am going for an interview of a senior Java developer, what kind of questions I should expect. 

Top 10 Tough Core Java Interview Questions Answers for Programmers

tough core Java interviews questions and answers
What is a tough core java interview question? Why do people look for tough Java questions before going for an interview? well, I don't think I need to answer these tough questions because it's pretty natural to prepare for tough questions even if you are not expecting tough questions from core Java. If you are prepared for the tough and tricky Java interview question then you feel more confident and answer other Java interview questions with confidence. 

Top 5 Big Data, Spark, and Hadoop Courses for Beginners in 2025 - Best of Lot

Hello Java programmers, if you want to learn Big Data and related technologies like Apache Hadoop, Spark, Hive, Flume, etc in 2025 and looking for the best resources like books, tutorials, and online courses then you have come to the right place. Earlier, I have shared the best free Big data courses and best courses to learn Spark but a lot of you asked me about the more comprehensive and up-to-date Big data course recommendations. So, I have come up with this list which contains the best-paid courses you can join to learn Big Data in 2025. Although the courses are not free, they are very affordable, particularly Udemy courses which you can get for just $10 on Sales. They are also very comprehensive, up-to-date, and trusted by millions of developers and probably the best resources to learn Big Data online in 2025. 

Top 5 Free Apache Spark Course for Beginners to Learn Online in 2025 - Best of Lot

Hello guys, if you are thinking of learning Apache Spark to start your Big Data journey and looking for some excellent free resources, e.g., books, tutorials, and courses, then you have come to the right place. This article will share some of the best free online Apache Spark courses for Java, Scala, and Python developers. If you don't know what is Apache Spark? And Why it's so crucial in the Big Data world, then let me give you a brief overview first. Apache Spark is another cluster computing framework like Hadoop, which analyzes a vast data set. Still, it's much faster than Hadoop, which makes it ideal for today's high computing needs, like processing a massive amount of data.

Top 6 Free Courses to Learn Ethical Hacking and Penetration Testing in 2025 - Best of Lot [UPDATED]

Hello folks, if you want to learn Ethical Hacking and looking for free online courses, then you have come to the right place. Earlier, we have shared the best Cyber Security Courses, best CompTIA Security+ exam courses, and today, we are doing share free Ethical hacking courses for you. Most of us have even a little bit of knowledge about the subject or industry that would be ideal if you start a career in that field, but the problem for most people is finding the right course or program that help you master these skills and become professional in the field and click on this article likely shows that you are interested in ethical hacking.

Top 10 Programming Languages to Learn in 2025 [UPDATED]

Hello guys, we're just one week away from 2025. This is when most of us start making our goals like physical goals, educational goals, and financial goals. As a programmer, one of our goals is to learn new technologies and programming languages, but which languages should you learn? Since acquiring a programming language requires both time and patience, you should learn a language worth the effort; I mean., it can reward you with a better job and career growth. In this article, I will share with you the top 10 programming languages you can learn in 2025 to get a job in your favorite companies like Google, Microsoft, and Facebook.

Top 10 Books Java Developers Must Read

Hello guys, If you are a Java developer and wondering what to read, then you have come to the right place. In this article, I will share 10 books on Java, Spring, and related technology a Java developer can read. I have included books for both experienced Java developer who is more inclined to learn about architecture stuff,  developing for Cloud, Microservice, Java 9 to Java 21 features, and Spring 6 features and thinking of learning Kotlin to improve their productivity. Still, I have not forgotten junior and less experienced Java developers or some thinking of starting their journey into the Java world

Top 5 Free Apache Maven eBooks for Java Developers

If you are working in Java for a couple of years, you surely know about Maven, the most popular tool to build Java applications. Recently I had shared 10 things about Maven Java developers should know, (if you have read it yet, you can read it here) and I receive a lot of good feedback about how useful those plugins and Maven, in general, are for Java developers. This motivated me to write more stuff about Apache Maven, and then I thought about sharing some of the free Maven courses and eBooks Java developers can use to learn Maven. 

Top 5 Free Courses to learn Django for Beginners in 2025 - Best of Lot

Hello guys, if you want to learn Django and looking for some free online Django courses to start with, then you have come to the right place. In the past, I have shared the best Python courses and best Django courses, and today, I am going to share free Django courses you can join online to learn this useful full-stack Python framework. There is no doubt that Python is the king of a Programming language at this moment, and one main reason for that is the huge number of powerful frameworks and libraries it has for different purposes like automation, data science, machine learning, scripting, data analysis,  and Web development is no different.

Top 5 Free Courses to Learn Deep Learning and Artificial Intelligence in 2025 - Best of Lot

Hello guys, if you are interested in learning about Artificial Intelligence and how to build AI and looking for free online resources, you have come to the right place. Earlier, I have shared free Machine Learning and Free Data Science courses, and in this article, I am going to share free Artificial Intelligence and deep learning courses for beginners. These free courses are created from Udemy, Coursera, edX, and Pluralsight and designed by experts and trusted by thousands of people who want to learn Artificial Intelligence. Clicking on this article link shows that you are very interested in learning more about artificial intelligence but wait! Learning artificial intelligence is not that easy and never will be. 

Top 6 Courses to learn Web Development and Web Design in 2025 - Best of Lot

Hello guys,  web development is one of the most lucrative fields of Software development, and demand for web developers is always increasing. It's also one of the exciting fields as you create web applications that are used by real people and you can also make an impact on millions of lives if you got a chance to work on the next unicorn or big tech companies like Amazon, Google, or Facebook. if you want to learn web development in 2025 and become a web developer or looking for a web development job then you have come to the right place. Earlier, I have shared the best free web development courses and in this article, I am going to share the best web development courses for beginners. 

Top 5 Free Courses to learn Design Patterns in Java and TypeScript in 2025 - Best of Lot

No matter how good or experienced a programmer is, they will run across issues when programming. As a number of problems arise in code, you may see some commonalities, and when you try to address them, you may detect certain patterns. The term "Design pattern" comes into play here. Design patterns, in basic words, are tried-and-true solutions to common programming problems. For instance, creational design patterns address object creation issues.

Top 5 Courses to Learn Cyber Security Online in 2025 - Best of Lot

Hello folks, if you want to learn Cyber Security in 2025 and looking for the best online courses to learn Cyber Security to start your career, then you have come to the right place. Earlier, I have shared free Cyber Security courses and websites, and in this article, I am going to share the best Cyber Security online courses anyone can join to learn security essentials. These are also the best courses from popular online platforms like Udemy, Coursera, and Pluralsight and great resources to learn about Cyber Security, Ethical Hacking, Information Security, and much more. If you want to become a Cyber Security specialist, you should definitely check out these courses. 

Top 15 Courses to Learn System Design and Software Architecture in 2025 - Best of Lot

Software design or System design is one of the tricky concepts to master. You can quickly learn a programming language like Java or Python, but creating software using that programming language is a totally different thing. That's where software design and coding skills come to the rescue. It's actually an art to structure your program, design your modules, specify boundaries and interactions with other parts of the system so that they are easier to read, maintain, and flexible to change. It's one of the most essential skills for a software developer but often gets ignored. If you look for an online course to learn Software design and architecture, you won't find many, forget about good ones.

Top 10 Online Courses to Learn Data Structure and Algorithms in 2025 - Best of Lot

Hello guys, In the past, I have shared a lot of useful resources like books and tutorials to learn Data Structure and Algorithms for both beginners and experienced programmers. I have also shared a lot of Data Structure and Algorithmic interview questions like this and their solutions in Java. Still, I have got continuously queries about excellent online courses to learn Data Structure and Algorithms in Java. Even though the topics are completely independent with the programming language, Java developer definitely likes the online courses which teach Data Structure and Algorithms in Java, and that's why my recent post about best algorithms courses, which includes algorithms courses from JavaScript and Python didn't impress my readers.

Java Program to find Armstrong numbers with Example

Armstrong number Example in Java
How to check if a number is an Armstrong number or not? or write a Java program to find Armstrong's number? This is a common Java interview question asked on-campus interviews and fresher-level interviews. This is also a popular Java programming exercise on various schools, colleges, and computer courses to build programming logic among Students. An Armstrong number is a 3 digit number for which the sum of cube of its digits is equal to the number itself. 

How to Find Missing Number in a Sorted Array in Java [Solved]

Today's coding problem is not very new, it's an age-old classic Programming interview Question. You have a sorted array containing n - 1 unique number starting from 0 to n - 1. There is only one number missing in this range and you need to find that out. I mean you need to write a Java method to find the missing number and print its value in the console. Some of you might have seen this question before, but if you have not been asked this question before, what is the first approach comes into your mind to solve this question? Since only one number is missing, many programmers come up with the approach of iterating over the array, and comparing each element with the expected one like the first element should be 0, the second element should be 1, and so on.

How to check if strings are rotations of each other in Java? String Rotation Example Solution

String-based algorithmic questions are very popular in Java interviews e.g. checking if two String is the anagram of each other (see), or checking if given String is a palindrome (see), or just finding permutations of given String (see). One of such popular String-based interview questions is about to check if two Strings are a rotation of each other in Java. In order to solve this question, you should know what is String rotation? Well, A string is made of characters and you just rotate the String around any character like "programming" will become "ingprogramm" if we rotate the String on the trailing character 3 times.

How to check if Array contains given Number or String in Java [ Linear Search vs Binary Search]

Hello guys, one of the common coding questions from Java interviews is how to test if an Array contains a certain value or not? This is a simple question, but sometimes interview pressure makes candidates nervous. In this article, you'll learn how to solve this problem using different approaches. Since an array in Java doesn't have any inbuilt method for searching values, interviewers prefer to ask this question, to see how a candidate deals with such a situation. If you have good knowledge of Java API, then you will immediately come to know that there are alternatives available like using the binarySearch() method of Java Java .util.Arrays class or taking advantage of ArrayList contains method by first converting your array to ArrayList.

Top 6 Courses to Learn Google Cloud Platform or GCP in 2025 - Best of Lot

Hello folks, if you want to learn Google Cloud Platform in 2025 and looking for the best resources like online courses, books, websites, and tutorials then you have come to the right place. Earlier, I have shared the best free Google Cloud platform courses and best websites to learn GCP, in this article, I am going to share the best online courses to learn Google Cloud Platform in 2025. The Google Cloud Platform, or GCP, is similar to Amazon Web Services and is a public cloud vendor catering to businesses and enterprises. Customers can use the Google Cloud Platform to access the computer resources in Google's data centers present across the world. It is offered either as a free addition or on a pay-per-use basis.