How to setup JNDI Database Connection pool in Tomcat - Spring Tutorial Example

Setting the JNDI Database Connection pool in Spring and Tomcat is pretty easy. Tomcat server documentation gives enough information on how to set up a connection pool in Tomcat 5, 6, 7, 8, or 9. Here we will use Tomcat 7 along with the spring framework for creating a connection pool in the Tomcat server and accessing them in Spring using JNDI code. In our last article, we have seen how to set up a database connection pool in Spring for a core Java application that doesn't run on a web server or application server and doesn't have a managed Java EE container.

How to create PDF File in Java - iText Example

Hello guys, generating PDF files in today’s enterprise applications is quite common. Doing this with Java is not an easy task as Java does not gives default api’s to handle PDF files. No worries, iText jar is for you. Earlier, I have shared about iText vs Apache FOP, two of the most popular libraries to create PDF files and today, I will show you an example of how to create a PDF files using the iText library in Java. If you are not familiar,  iText is a free Java-PDF library that allows you to generate PDF files on the fly (dynamically). iText is an ideal library for developers looking to enhance web- and other applications with dynamic PDF document generation and/or manipulation.

How to add new columns to an existing table in SQL Server database? Example tutorial

Hello guys, adding a new column to an existing table with data is always tricky and if you don't pay enough due diligence then you risk of corrupting or deleting existing data. You need to know what data is there, how much data is there, to gauge how long your query is gonna take to complete in production. Also, you cannot add NOT NULL columns into an existing table if they are not empty and you don't have a default value specified. If you know SQL then you probably know that you can add columns to an existing table in SQL Server using the ALTER command. It not only allows you to add a column but to drop columns as well.

How to dynamically create a div in jQuery? Example

Many times you need to create an HTML element and dynamically add that into DOM without reloading the page. The traditional way of doing this is by using JavaScript's innerHtml() function but jQuery provides better ways to achieve the same effect. You can use jQuery DOM manipulation methods like append(), appendTo() or html() to add new HTML elements like div, paragraph, headings, image into DOM without reloading the page again. In this tutorial, I will show you how to dynamically create a div and add that into a page by using pure jQuery.

Binary Tree PreOrder Traversal in Java - Recursion and Iteration Example

Unlike a linked list and array which are linear data structure and can only be traversed linearly, there are several ways to traverse a binary tree because of its hierarchical nature. The tree traversal algorithms are mainly divided into two types, the depth-first algorithms, and breadth-first algorithms. As their name suggests, in a depth-first algorithm, the tree is traversed downwards (towards the depth) before the next sibling is visited, the Pre Order, InOrder and PostOrder traversal of a binary tree is actually depth-first traversal algorithms. On the breadth-first algorithm, also known as level order traversal, the entire breadth of the tree is traversed before moving to the next level, hence it is also known as level order traversal.

How to convert Result of SELECT Command to Comma Separated String in SQL Server? Example

Sometimes, you need the result of the SQL SELECT clause as a comma-separated String e.g. if you are outputting ids of white-listed products. By default, the SELECT command will print each row in one line and you get a column of names or ids. If you need a comma-separated String then you probably need to use a text editor like Notepad++, Edit Plus, or a tool like Microsoft Excel to convert that column of values into a big CSV String. I often use a text editor like editplus to replace the \n to comma (,) to create such CSV string because it supports regular expression-based find and replaces operation.

What is Strangler Pattern in Microservices? How to use it?

As organizations embrace the microservices architecture style, the need to modernize legacy systems and seamlessly transition to microservices becomes crucial. However, undertaking a complete system overhaul can be daunting and risky. This is where the Strangler Pattern comes into play. The Strangler Pattern offers a structured approach to incrementally transform monolithic applications into a more flexible and scalable microservices architecture. In the past, we have understood about  Database Per Microservices, CQRS, Event Sourcing, Backend for Frontend, and Circuit-breaker pattern and in this article, we will explore what the Strangler Pattern entails and how to effectively employ it to ensure a successful migration.

How to create and call stored procedure in MySQL with IN and OUT parameters? Example Tutorial

It's hard to remember the exact syntax of, how to create a stored procedure in MySQL until you are creating and working on stored procedure frequently, simply because the syntax is not a one-liner. You need to remember the exact syntax if you are using the MySQL database from the command line. What help, in this case, is, quick examples. In the last couple of MySQL tutorial we have seen How to find the second highest salary and How to join 3 tables in one query; In this MySQL tutorial we will see a couple of examples of creating stored procedure and calling stored procedure using IN and OUT parameters. A

Difference between application/x-www-form-urlencoded and multipart/form-data in HTTP/HTML?

Recently in one of the Java web developer interview, one of my readers asked about the difference between x-www-form-url-encoded and multipart/form-data MIME types. In HTTP, there are two ways to send the HTML form data to the server either by using ContentType application/x-www-form-urlencoded or by using multipart/form-data. Even though both can be used to send both text and binary data to the server there is a subtle difference between them. In the case of x-www-form-urlencoded, the whole form data is sent as a long query string.

How to find Length of String in SQL Server? LEN() Function Example

One of the most common task while writing SQL queries or stored procedure is to find the length of String. Since most of the columns are VARCHAR, you often need to find the length before taking any action. In Java, you can find the length of String by using the length() method but how about SQL Server? How will you find the length of String in Microsoft SQL Server in general and Microsoft SQL Server 2016 in particular? Well, you can use the LEN() function to find the length of a String value in SQL Server, for example, LEN(emp_name) will give you the length of values stored in the column emp_name. This method exists from SQL Server 2008 onwards which means you can use this function in SQL Server 2012, 2014, 2016 and latest version of Microsoft SQL Server i.e. SQL Server 2017.

How to read and write Images in java using ImageIO Utility

Writing an Image file in Java is very common scenario and in this article we will see a new way to write images into file in Java. javax.imageio.ImageIO is a utility class which provides lots of utility method related to images processing in Java. Most common of them is reading form image file and writing images to file in java. You can write any of .jpg, .png, .bmp or .gif images to file in Java. Just like writing, reading is also seamless with ImageIO and you can read BufferedImage directly from URL.

Maven JAR Artifiact Dependency Search Not Working in Eclipse - Solved

Recently I face a strange issue while using Maven in Eclipse via M2Eclipse plugin. I have created a Maven Java project in Eclipse and subsequently tried to add Spring framework as a dependency, to my surprise, nothing was happening. Eclipse was not able to search dependency in Maven central repository. I was surprised because I have never faced this issue while I was using the M2Eclipse plugin for a long time. After some trial and error, I realized that this is my brand new workspace and I am running with Eclipse Luna, the newest version of Eclipse which I had just downloaded a couple days of the back. My first hunch was that Eclipse might not able to connect to the Internet, and to verify that I tried connecting the Eclipse market place, and boom it was working fine.

How to enable/disable an element using jQuery and JavaScript? Example

Sometimes we need to enable and disable input elements like text box, radio buttons, or checkboxes, but every time you make a change you need to reload the HTML? The question is, how can we do it dynamically without loading the page? Well, we can use JavaScript, particularly jQuery to do this. An element can be disabled in HTML by setting disable property to true and enabled again by setting disabled=false. By using jQuery, you can grab the element you want to enable or disable and change this property by using the prop() or attr() function, depending upon the version of jQuery you are using.

What is Abstract Class and Method in Java? Examples and Frequently asked Questions

Both abstract class and abstract methods are very important concepts in core Java and every Java developer should have good understanding of what they are, when to use them and how to use them. They are also very popular on core Java job interviews as well as on Oracle Java certifications e.g. OCAJP or OCPJP.  You will often find a lot of code based questions testing essential core Java concepts based upon abstract class and methods in the real exam. All good mock exam simulators e.g. Whizlabs and Certification-questions also contains a lot of questions testing and explaining these key concepts, which shows how important they are for Java developers. 

How To Use The JSON Web Token (JWT) In Spring Boot And Spring Security Project

Hello guys, In the world of web application security, JSON Web Tokens (JWTs) have gained significant popularity. JWTs provide a secure and efficient way to handle authentication and authorization in modern web applications. In this article, we'll explore the ins and outs of using JWT in a Spring Boot and Spring Security project. From generating tokens to verifying and handling them, we'll cover everything you need to know to leverage JWT effectively in your applications.