The @RequestMapping annotation is one of the most important annotation of Spring MVC which provides mapping of HTTP requests to controller methods, I mean Java methods on Controller class for processing. If you wonder, how Spring handles a particular request and which method from controller class is called for a particular request, answer lies on @RequestMapping annotation. This annotation maps web request to methods on controller class. You can apply @RequestMapping on class or method level of your controller. This is a powerful annotation and give you a lot of option to sophistically map a w ..read more

Hello guys, if you are a beginner looking for a job as Java developer but not sure you should know then you have come to the right place. I get fresh computer engineers from colleges, interns, and new hires, so for the kids fresh out of school, here are some of the things I wish/hope they know. This is not just true for Computer science engineers and IT graduates but also to self-taught developers who have learned coding by themselves by following any YouTube video or joining an online course.  Java, Unix, Tibco RV and FIX Protocol Tutorial ..read more

I know how frustrating is to see "Exception in thread "main" java.lang.NoClassDefFoundError" while running your Java application. This is one of the dreaded problem in Java  which is also a manifestation of NoClassDefFoundError in Java. I have seen it a couple of times and spent quite a lot of time initially to figure out what is wrong, which class is missing etc. The first mistake I did was mingling java.lang.ClassNotfoundException and NoClassDefFoundError, in reality, are totally different, and my second mistake was using the trial and error method to solve this java.lang.NoClassDe ..read more

Hello friends, in last a couple of years, I have seen an increase in coding problems where interviewer expect you to solve using functional programming concepts and particularly map() and flatMap(). They do this because they want to know whether you know about these methods or not and whether you can use them in real world scenarios like solving coding problems. I have been collecting such coding problems and today, I am ready with 10 such map and flatMap related coding questions which I am going to share with you. The beauty of these coding interview questions is that you can easily solve the ..read more

Hello guys, Cloud Computing is a great skill to learn in 2024 as more and more companies are moving to Cloud. and Azure is a cloud computing offered by the gain Microsoft for deploying your website or a web application as well as developing testing and managing your application with more than two hundred different services in eighteen categories ranging from computing to databases and others for IoT services. Java, Unix, Tibco RV and FIX Protocol Tutorial ..read more

In some cases while using Hibernate for object-relational mapping, you will encounter the N+ 1 select problem. That is, Hibernate will execute (n+1) queries to populate a list of records of size n, I mean 5 SELECT queries will be required to populate 4 records. This happens when each object contains reference of another object which needs to be populated. For example, suppose you have list of authors and you want to print out title of books written by each other. A naive ORM will first do a SELECT query to load all authors and then execute another N SELECT query to load book for each auth ..read more

The Apache Tomcat is one of the most popular web server used to deploy Java web application comprising HTML, JavaScript, Servlet and JSP. If you have ever worked in a Java web application you might have found yourself using Tomcat everywhere, from test environment to production. It is the defacto standard for deploying Java Web applications without EJB because using application server like WebSphere or WebLogic is both costly and superfluous for such web application. As a Java developer, working in Java and Spring based web applications, you should know some basic and advanced detail of Tomcat ..read more

A good knowledge of HTTP protocol is must for a RESTful Web Service developer because REST uses HTTP principles and a good portion of its popularity is due to HTTP itself. One of the important part of HTTP is the status code, which gives useful information related to client request. They are also known as HTTP response code because they are sent in header on HTTP response by Server to indicate what happened with client's request. The status codes ranges from 100 to 500 but not all of them are valid and useful. Instead the first number e.g. 1xx or 2xxx denotes the class of status codes.  J ..read more

The Gson library is a gift from Google to Java developers. It provides the simplest but powerful mechanism to deal with JSON documents in Java. By using Gson library, you can parse JSON String to generate Java objects, serialize a Java object to create a JSON document. You can even pretty print JSON String by setting some option to the Gson class, which is the main helper class to interact with Gson library. It also provides mechanism to deal with nulls e.g. you can include null on JSON String or you can omit them. By default Gson print JSON in compact format where null fields are not exported ..read more

Servlet and Filter are two of the essential concepts defined in Servlet specification. They are core of any web application because most of the request will pass through them. This is why they are also very popular on Java Web developer interviews. What is the difference between a Servlet and a Filter is one of the most common and interesting interview question related to Servlet. If you can explain the difference clearly, you improve your chance of hiring a lot. In order to understand and explain the difference, you must understand what is the purpose of Servlet and Filter, How they work and ..read more