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Friday, September 30, 2022

Difference between HashMap vs IdentityHashMap in Java? Example

The IdentityHashMap is one of the lesser known Map implementations from JDK. Unlike general purposes Map implementations like HashMap and LinkedHashMap, it is very special and its internal working is quite different than HashMap. The main difference between IdentityHashMap and HashMap in Java is that the former uses the equality operator (==) instead of the equals() method to compare keys. This means you need the same key object to retrieve the value from IdentityHashMap, you cannot retrieve values by using another key that is logically equal to the previous key. 

Sunday, September 25, 2022

How to set the logging level in Spring Boot - Example Tutorial

Hello guys, if you are wondering how to set the logging level on spring boot then you have come to the right place. In the past, I have shared the best Spring Boot courses and free courses to learn Spring MVC and in this article, I will share how to set logging levels like DEBUG and INFO in Spring Boot.  How do we configure the logging level of our Spring boot application is one of the questions that arise when developing a large application. Because we need to trace errors, warnings, informational data when running our application and to this, Spring has introduced Spring boot logging configurations. 

Friday, September 23, 2022

How to use @ResponseBody and @RequestBody in Spring MVC and REST? Example Tutorial

Hello guys, if you are wondering what is @RequestBody and @ResponseBody annotation in Spring MVC and Spring Boot then you have come to the right place. Earlier, I have told you about the @RestController annotation and in this article, I am going to explain to you what is RequestBody and ResponseBody annotation, how to use them, and when to use them with simple examples. While working with REST API, we may need to bind HTTP requests and response bodies with the domain object. To bind this, we use we can use the @ResponseBody and @RequestBody annotations in Spring MVC. 

Monday, September 19, 2022

Difference between Binary Tree, Binary Search Tree (BST), and Balanced Tree (AVL and Red Black Tree)?

Hello guys, if you are preparing for technical interview for Software Development job then you must prepare well for Data Structure and Algorithms. It is often the difference between selection and non-selection and when it comes to Data Structure, binary search tree is one of the tough topic to master. In the past, I have shared 100+ data structure questions and 40+ binary tree questions and today, I am going to share one of the popular theory or concept questions related to binary tree data structure.  The Tree data structure is one of the essential data structures, but unfortunately, many programmers don't pay enough attention to learning Trees, particularly advanced tree data structures like balanced trees like AVL and Red-Black tree. 

Saturday, September 17, 2022

Top 50 Core Java Interview Questions and Answers for Beginners

Hello guys, If you are preparing for your next Core Java interview and looking for some common questions to practice or check your knowledge, then you have come to the right place. In this article, I'll share 50 Core Java Interview Questions from various companies. I have already discussed the answers to these questions in this blog or Javarevisited, so I have just put the link and given hint or mentioned the key point you need to know to answer these questions. First, you should try to answer it yourself, and if you cannot then go to the link and find the answer. You can also compare your answer with mine and learn a few things here and there.

Friday, September 16, 2022

Top 20 Linux and SQL Interview Questions for Java and IT Professionals

Hello guys, If you have worked as a software developer or Java programmer then you know that SQL, Linux, and Networking fundamentals are essential skills for any Java developer, especially for server-side Java programmers. It actually doesn't matter whether you are applying for the job as a Java developer or C++ developer, Python developer or Ruby programmer, SQL and UNIX always have some role to play in your career. It's even essential for people who have less to do with programming like application support guys, business analysts, project managers, and subject matter experts.  Hence, it's imperative for any programmer or IT professional to prepare both SQL and UNIX well before going for any job interview.

Thursday, September 15, 2022

21 Frequently Asked Java Interview Questions Answers for 2 to 3 Years Experienced Programmers

If you have been to a couple of Java interviews then you know that there are some questions that keep repeating like the difference between == and equals() method and many of its popular cousins like HashMap vs Hashtable, ArrayList vs LinkedList, the difference between equals() and hashCode(), or difference between Comparator and Comparable in Java. I call them frequently asked Java interview questions, and I suggest every Java developer make a list of them for their own reference and revision. I am sure many Java programmer already has such a list of questions handy if you don't have then this is a good time to find and make your own list, or if you are in rush then you can also buy my book Grokking the Java Interview, which contains many such questions. 

Saturday, September 10, 2022

Top 12 Servlet JSP Interview Questions for Java JEE Developers

Hello guys, Servlets and JSP Interview Questions are the core of any Java JEE Interview and why not they are the back bone of Java Web technology. While the industry have moved from JSP and JSF to React based frontend there are still millions of applications which are using JSP and Servlet in backend. They are also the underlying technology for any web framework on Java like Spring MVC or Spring Boot and It's expected from candidates to have good knowledge of Servlet, JSP, EJB, Struts, or Spring in any JEE interview. That's why Servlets and JSP Interview Questions are very common in any JEE Interviews along with some questions from core Java, Some interview Questions from Spring, and Some EJB interview questions

Thursday, September 8, 2022

Top 20 Java Web Service Interview Questions with Answers

Java Web Services Questions and Answers
Web Services interview questions are part of J2EE interviews for jobs which are looking for some experience in Java web services Space. Most of the Web services questions come from two different ways of implementing Web Services like SOAP and REST. SOAP is standard and mature way of calling Web Services which uses XML while REST is a new way of implementing Web Services which is based on HTTP protocol. In fact REST Web Service interview questions are getting more and more popular on the web services interviews in Java, So if you are going for any Java J2EE interview which require some web service experience, be prepared with both SOAP and REST Web services questions.

Thursday, September 1, 2022

13 Spring Boot Actuator Interview Questions Answers for 3 to 5 Years Experienced Java Developers

If you have used Spring Boot, you may know that Spring Boot is all about convenience, and the Spring Boot actuator is one of such features that provides a convenient way to interact with your app using HTTP and JMX. It's also essential from the Spring Boot interview point of view. While I did include some Spring Boot Actuator questions in my earlier post about frequently sked Spring boot interview questions, many of you asked for more questions to cover Spring Boot Actuator in depth, so I decided to write a separate article. In this article, we will see some popular Spring boot Actuator interview questions and, along the way, learn more about this helpful Spring boot Feature