How HashMap works in Java?

Hello guys, if you are looking for an answer of popular Java interview question, how HashMap works in Java? or How HashMap works internally in Java then you have come to the right place. In this article, I will not just answer those question but also many related questions like How get() and put() method works in Java? what role equals() and hashcode() play in HashMap, How HashMap resize itself, and why key object of HashMap should be Immutable in Java. Let's start with the basics first. HashMap in Java works on hashing principles. It is a data structure that allows us to store object and retrieve it in constant time O(1) provided we know the key. Also this is one of my most popular article with more than 6 million views and I have now updated it to include latest information like how HashMap now uses a balanced tree instead of linked list for storing collision objects and new diagrams on HashMap working which provide visual explanations. 

Top 12 SQL Query Problems for Coding Interviews (with Solutions)

Hello guys, if you are looking for SQL query examples from interviews or SQL Query Practice questions to improve your SQL skill or just to prepare for tech interviews  then you have come to the right place. Earlier, I have shared best websites to learn SQL and Practice Query online and in this article, I am going to share 12 popular SQL query questions from interviews. SQL is an important skills for both programmers and data scientist, even people from QA and BA stream also need to know SQL to do their job well in this era or data driven world. That's why SQL queries are also quite popular on interviews. 

Top 50 Java Programs from Coding Interviews

Coding problems are an integral part of any programming job interviews, and Java development interviews are no exception. I would even suggest you should never hire anyone without testing their coding skill, but coding is also an art, and more often than a good coder is also an excellent developer. If you look at tech giants like Amazon, Facebook, and Google they thoroughly test the coding skill of any developer they hire, notably Amazon who first send online coding exercises to filter Java programmers who can code from those who can't code. This online test usually gives you requirements and ask you to write a program in a limited time, usually 2 to 3 hours. The application should meet the output provided by the exercise itself. These type of tasks are very tough to crack if you don't have excellent coding skill.

42 Programming Interview Questions for 1 to 3 Years Experienced Programmers (with Answers)

Hello guys, if you are preparing for programming job interviews and looking for previous asked questions or popular questions to get idea what topics are important for interviews then you have come to the right place. In the past, I have shared system design questions, SQL questions, UNIX questions and Java questions and in this article, I am going to share 42 programming interview questions for 1 to 3 years of experienced programmers. Though, its also useful for programmers up to 5 years of experience and we will start with programming questions from telephonic round of interviews. Due to COVID and work from home culture, in the last few years, phone interviews also known as the telephonic round has become the single most popular way to screen candidates in a programming job interview. It's easy for both parties to gauge each other, the candidate doesn't need to travel to the prospective Employer's premises and the Interviewer also doesn't need to make any unnecessary arrangements.