Top 7 AWS Solution Architect Associate Certification Practice Test and SAA-C03 Exam Dumps in 2025

Hello guys, if you are preparing for the AWS Certified Solutions Architect Associate (SAA-C03 and SAA-C03) certification exam and looking for challenging practice tests to assess your preparation then you have come to the right place. In this article, I am going to share the best Practice test and questions to prepare for the AWS Solution Architect Associate  (SAA-C03) exam from Udemy, Whizlabs, and other portals, totaling more than 2000+ practice questions. These practice tests are created by AWS experts and certified developers and Solution architects like Stephane Maarek and Cloud guru Ryan Kroonenberg. Mock simulators play an important role in any certification and the AWS Solution Architect Associate-level exam is no different.

Top 5 AWS Certified Cloud Practitioner Exam (CLF-C02) Practice Questions & Dumps in 2025

As I have said before, Practice tests and exam dumps play an important role in not just passing the AWS Certified Cloud Practitioner certification (CLF-C02)  but also achieving a high score, which can truly set you apart from your competition. There are multiple benefits of going through practice tests and solving problems on an exam simulator before actual example. For example, it will help you find your strengths and weakness in advance so that you can understand your weaker areas better. They also help you to develop speed and accuracy, which is key to pass the time-bound exam like the AWS Certified Cloud Practitioner (CLF-C02) certification from Amazon.

Top 5 Practice Tests for AWS Certified Developer Associate DVA-C02 Certification in 2025 - Best of Lot

Hello guys, time and again I have said that practice questions and mock tests are an integral part of passing AWS certifications be it AWS solution architect or this AWS developer associate exam. They not only help you to prepare in an exam-like environment with time constraints but also reinforce and solidify whatever you have learned from online courses, books, tutorials, and white papers. It doesn't matter whether you have joined AWS developer courses like Neal Davis' AWS course on Udemy or Stephane Maarek's DVA-C02 course, unless and until you have practiced enough problems, you are not really ready for the exam.

Top 5 Course to Crack AWS Solution Architect Professional (SAP-C02) Certification Exam in 2025 - Best of Lot

Hello guys, today, I am going to talk about the toughest AWS certification and probably one of the toughest Cloud certifications as well, yes, you guessed it right. I am talking about the AWS Solution Architect - Professional certification. This is not just the toughest but also most desired and reputed cloud certification and not many developers and system admin can pass it. It's slightly easier to pass the AWS Solution Architect- Associate exam but this one is a completely different nut to crack. You would need an in-depth knowledge of not just cloud computing but also many essential AWS services to crack this coveted certification. 

Top 5 Online Courses to Crack AWS Certified Developer Associate Exam (DVA-C02) in 2025 - Best of Lot

Hello guys, you might have heard about AWS certifications and if you, as a Programmer, Software Developer, or DevOps Engineer, wondering which certification to pursue in 2025, I would suggest going for AWS Developer Associate Certification by Amazon Web Service. The AWS Certified Developer - Associate examination is intended for Software Developers and Programmers who have one or more years of hands-on experience developing and maintaining an AWS-based application. Since the future of Software Development is in Cloud it makes sense for Software Developers to get certified for their cloud development skills and given that AWS is the most popular and biggest Cloud platform it makes sense to go for AWS Developer Associate certification.

Top 5 Udemy Course to Crack AWS Certified DevOps Engineer Professional Exam DOP-C02 in 2025 - Best of Lot

Do you want to become a DevOps engineer for cloud platforms like AWS but don't have a target, then you have come to the right place because today, I am going to talk about AWS Certified DevOps Engineer Professional Exam and share the best online courses to prepare well for this prestigious exam. While being a good developer is great and writing scalable codes is an asset, delivery time is very important in all IT projects as well, and that was what prompted the first DevOps day. DevOps is a combination of word development and operations which is the operations that lead to faster software development. Getting a certificate in DevOps enables professionals in IT to display their skills and qualifies them to be part of DevOps leaders.

Top 7 Books and Udemy Online Courses to Crack the PMP Certification Exam in 2025 - Best of Lot

If you are in the Project management and People management area, then you might have heard about PMP certifications, one of the most reputed and sought-after IT certifications for project managers and people aspiring to start their career in project management. PMP is a short form of Project Management Professional and is offered by the Project Management Institute (PMI). As I said, it's one of the most reputed certifications for project management professionals. There is an immense global demand for project managers. Several leading and best companies hire certified project managers to manage their projects. According to a PMI report, over 2 million project management roles need to be filled every year.

Top 7 Udemy Courses for CompTIA A+ Certification in 2025 (with Practice Test) - Best of Lot

Hello guys, CompTIA A+ is a famous certification among beginners who wants to start a career as an IT professional and learn information technology in general. This IT certification doesn't have any requirement to take it and it is recognized in all companies around the world and includes some topics such as information security, network administrator, computer repair, operating systems, and many more computer fundamental topics. If you don't know what is CompTIA let me give you a brief overview. CompTIA stands for Computer Technology Industry Association.

20 Best Coursera Professional Certificates for IT Professionals in 2025 [UPDATED]

Hello guys, If you are thinking of a career in Information Technology and Software Development in 2025 but lack a Computer Science degree or a Professional degree then you don't need to disappoint. Coursera's professional certificates can give you all the knowledge and credential to start a career in Information Technology. If you don't know, Coursera launched Professional Certificates recently which can help you get job-ready for an in-demand career field in less than a year. You can earn a career credential, apply your knowledge to hands-on projects that showcase your skills for employers and get access to career support resources.

Top 50 Free Spring Certification Practice Questions Answers for Java Developers

Hello guys, if you are preparing for Spring Professional certification in 2024 and looking for free Practice questions then you have come to the right place. I have an excellent update to share with you from 5th April 2024 onward, you don't need to complete any mandatory training or Spring Pro courses to become eligible for Spring certification, its free like it was before VMware acquired and now you just need to buy voucher to give this exam.  Earlier, I have shared best spring books and courses and today, I am going to share 50+ spring boot practice questions for this certification. To be honest, preparing for IT certification like Oracle's Java certification or VMware's Spring Certification required a lot of hard-work. I have seen many experienced Java developers failing these certifications and losing money and time due to overconfidence and lack of preparation. 

Does Vmware's Spring Professional Certification help Java Programmers in Jobs and Career Growth?

One of the frequently asked questions among Java and Spring developers is whether Spring certification is valuable? Or does Spring Professional Develop Certification help you in Job and Career? These questions are not very different from what a Java developer asks about Oracle's Java certification (see here). The short answer to these question is Yes, Spring Professional Certifications (VMware EDU-1202  are valuable, as it's not just provides Industry recognition for your knowledge, experience, and skill but also improves your knowledge about Spring Framework, Spring Boot, Spring Data JPA and Spring Ecosystem which sets you apart from the millions of Java and Spring developer who are not certified. Of course, as with any certification, the most valuable part apart from recognition is the learning process, and this is true for Spring certifications as well.

Top 5 Free AWS Solution Architect Associate Certification (SAA-C03) Practice Tests, Mock Exams, and Dumps

Hello guys, It seems everyone is over the cloud nowadays. Wherever I go people talk about Cloud computing and cloud platforms like AWS, Azure, Google Cloud, Digital Ocean, etc. And, there is no better way to learn cloud than preparing for certifications. I know so many people who are preparing for the AWS solution Architect exam for learning AWS and that's why I have started sharing my tips for learning AWS and passing the AWS solution architect certification exam. You might have noticed a couple of my posts related to AWS certifications like in the past I shared best online courses to crack AWS solution architect associate exam. But, I have said this multiple times that without practice tests and mock exams, your preparation for AWS certification be it solution architect or cloud developer is not complete.

Top 5 Course to Crack Google's Associate Cloud Engineer Certification Exam in 2025 - Best of Lot

Hello guys, If you are looking to pursue a career as a Google Cloud Engineer or merely just want to acquire a cloud certificate to add to your colorful resume, then taking the Google Cloud Engineer exam might be just the right thing for you. Google Cloud Platform or GCP is one of the top 3 public cloud providers along with AWS and Microsoft Azure and the demand for certified Google cloud professionals is growing exponentaitonal because of increased adoption of the Google Cloud Platform. If you already have a fair amount of experience, then you may want to go for the Professional Cloud exam. But if you are a newbie, or looking to add more certifications to add your CV then the Associate Cloud Engineer exam is the way to go.

Top 5 Practice Tests & Courses to Crack Azure IoT Certification AZ-220 Exam in 2025 - Best of Lot

Hello guys, if you are preparing for the AZ-220 exam or Azure IoT certification in 2025 and looking for the best AZ-220 certification courses then you have come to the right place. In the past, I have shared the best AZ-900 courses, best AZ-104 courses, and best AZ-204 courses and in this article, I am going to share the best online courses to crack Azure IoT certification or AZ-220 exam. These are the best resources to prepare for this exam and curated from popular sites like Udemy, Coursera, and Pluralsight.  Before we get to the best certification courses that you can use to clear the IoT AZ-220 certification exam, let me tell you what exactly is this AZ-220 Certification. 

Udemy vs Pluralsight Review 2025? Which is better to Learn to Code and Programming?

Hello guys, how are you doing? I am again back with answering one of the familiar doubts among online learners, Pluralsight, or Udemy? Which are the better websites for learning code and leveling up your programming skills? As a Java blogger and editor of a Medium publication, I often receive questions like this from my readers. Earlier I have answered questions like Pluralsight vs. CodeCademy and Udemy vs. CodeCademy but never explained about Pluralsight vs. Udemy, which many of my readers have been asking for a long time. Since Pluralsight and Udemy are two of the most popular online learning platforms and I also spend considerable time every day on each of them, I felt to write my review of Udemy and Pluralsight and explain the pros and cons of both Udemy and Pluralsight so that you can make an informed decision when it comes to learning tech skills online.

Top 7 DataCamp Courses to learn Python, SQL and Data Science in 2025 - Best of Lot

Hello guys, if you are looking for the best Datacamp courses to learn Python and SQL and become a Data Scientist in 2025, then you have come to the right place. In the past, I have shared the best udemy courses to learn Python and the best courses for data science. In this article, I will share both free and best Datacamp courses for Python developers and Data Science learners. Yes, you read it write, Datacamp also offers free courses and they are quality courses which you can take to learn at the skill on your own. If you don't know, Datacamp is a great platform to learn Data skills, and it has the best courses to learn Data skills like SQL, Data Science, and Python. 

Top 6 CompTIA Cloud+ Certification (CV0-002) Courses and Practices Tests in 2025 - Best of Lot

Hello guys, if you are preparing for the CompTIA Cloud+ (CV0-002) Certification exam and looking for the best online courses and practice tests to pass this exam then you have come to the right place. In the past, I have shared the best online courses to pass various CompTIA certifications like CompTIA A+, IT Fundamentals, Linux+, and Security+  exams and In this article, I am going to share the best CompTIA Cloud+ certification courses and practice tests to crack the CompTIA Cloud+ (CV0-002) Certification exam in 2025. These courses have been created by experts and trusted by thousands of developer who has passed this in-demand exam and you can also join them to prepare better for this CompTIA certification. 

Top 5 Courses to learn Amazon (AWS) QuickSight in 2025 - Best of Lot

Hello guys, If you want to learn AWS Quicksight and looking for the best online courses then you have come to the right place. Earlier, I have shared the best AWS courses and in-depth courses to learn essential AWS services like EC2 and DynamoDB and In this article, I am going to share the best online training courses and classes to learn AWS Quicksight in 2025. If you are working in AWS then you may have heard about the AWS Quicksight tool. The Amazon AWS Quicksight is a cloud-based fast business intelligence tool that can do analysis and make dashboards and graphs out of your data as well as the AWS resource that is used by your application so it combines them into one dashboard to get more insight into your data. 

Top 7 Figma Online Courses for UI and UX Design in 2025 - Best of Lot

Hello guys, if you want to learn Figma in 2025, one of the most popular UI and UX design tools, and looking for the best resources like tutorials and online courses, then you have come to the right place. Earlier, I shared the best web design courses and best web development courses, and in this article, I will share the best courses to learn Figma for U.I. and UX design in 2025. Having a good-looking website is not only beneficial but also necessary in today's world, and that's why U.I. and UX design skill is in high demand. There are a lot of jobs in both big and small companies for expert designers, and knowledge tools like Figma are going to improve your U.I. design skill for sure. 

Top 5 Courses to Learn Servlet and JSP for Java Web Developers in 2025 - Best of Lot

Hello guys, if you want to learn Servlet and JSP and look for the best Servlet courses, you have come to the right place. In the past, I have shared the best Servlet and JSP books and free Servlet and JSP courses and today, I will share the best Sevelt and JSP online courses from websites like Udemy Coursera and Pluralsight. These courses have been created by experts and trusted by thousands of developers to learn Servlet and JSP. You can also join them to learn these key technologies online from your home or office. Servlet and JSP are two of the most important web technologies for Java developers. In the framework age, you may not directly work with Servlet and JSP but knowing fundamentals like this always helps. 

Top 10 Pluralsight Courses for React Developers in 2025 - Best of Lot

Hello guys, if you are looking for the best React courses on Pluralsight, then you have come to the right place. Earlier, I have shared the best Pluralsight methods for Java developers, and today, I will share the best courses to learn React.js, one of the most in-demand skills for both Java and Fullstack developers. Pluralsight is one of my favorite learning websites because you can learn from subject matter experts and their courses are also well designed. They don't have giant classes of 50 hours, plus they have multiple courses where you can learn valuable skills in a couple of hours. That's what I like most because I never have that much time. 

Top 5 Course to Crack Google Cloud Professional Data Engineer Certification in 2025 - Best of Lot

Hello guys, If you are looking for a Cloud certification, then let me tell you that the Google Cloud Professional Data Engineers are currently in demand for their ability to maintain the process of accumulating, converting, and publishing data with a certain level of expertise on Google Cloud Platform. When I published my list of 10 Cloud Certifications for 2025, I have included a couple of Google Cloud certifications because there are not many Google Cloud certified compared to certified AWS and Azure Professionals. They are mostly known for putting machine learning models into operation, creating and structuring data processing systems to work accurately, and ensuring that the data is secure and scalable.

Top 5 Courses to Crack Docker Certified Associate Certification Exam in 2025 - Best of Lot

Hello guys, if you are thinking about the Docker Associate exam or want to become a Certified Docker associate and looking for the best online courses to start your preparation then you have come to the right place. In the past, I have shared the best courses to learn Docker and Kubernetes and today, I am going to share the best online courses to crack the Docker Certified Associate Exam in 2025. These are the best Docker courses from Udemy, Coursera, Pluralsight, and Whizlabs and are very useful for this Docker certification. They are created by experts like Nigel Poulton who is Docker Captain himself and they have also trusted ty thousands of Docker developers around the world.

Top 5 Online Courses to Learn Modules and Java 9 Features in 2025 - Best of Lot

The last couple of years was the year of releases for Java developers. With versions of JDK 9 to JDK 15, Spring 5, Spring Boot 2.0, and Spring Security 5.0, there was so much to learn for Java developers and all at once, but like many others, I didn't make a good process, and I am looking to turn it around this year. One of my top priority goals for this year is to learn new Java features as quickly as possible to write more about them. It's also essential for you to learn modern Java features to write better code and improve your day-to-day productivity with Java. The Java 9 release intends to change the way Java developers used to write code. It introduces a modular JDK so that developers can only include the modules that they need.

Top 5 DialogFlow Online Courses to build Chatbots using Python in 2025 - Best of Lot

Do you want to learn how to build chatbots? the darling child of Artificial Intelligence? If yes, then you have come to the right place. Earlier, I have shared the best Data Science and Machine Learning Courses and in this article, I am going to share the best Chatbot courses for beginners. I have helped many of my readers who wanted to build chatbots but didn't know where to start? I think joining an online course is a good idea, and if you are looking for some online courses, then you will find some good ones here, but before that, let's talk about chatbots. If you are not living under the rocks, you might have seen several applications of chatbots like in your online banking portal or any other website.

Top 5 Online Courses to Learn Flask for Web Development in Python in 2025 - Best of Lot

If one of your resolution this year is to learn web development with Python, then I must congratulate you on making the right choice. Python is the king of a programming language at the moment, and it has many frameworks and libraries to create a robust and scalable web application. One of the most notable of them is Flask, which is known for its simplicity and ease of learning. It allows you to create a web application with a tiny amount of code and work, because of that it's one of the most popular web application frameworks in the Python community and an ideal framework to learn for web development whether you are a beginner or someone with years of experience.

Top 5 Courses to learn Regular Expression in Java, PHP, and JavaScript in 2025 - Best of Lot

You might know that a Regular expression is a powerful tool for pattern matching and searching text. As a programmer, you often need searches like error messages in log files or particular information. Good knowledge of regex can help you to do your job more efficiently. Almost all programming languages support regular expressions. You will find APIs for creating and applying regex in Java, Python, Perl, JavaScript, C++, and others. Similarly, many tools and commands in Linux like grep, awk, and sed also support regex. This really helps while analyzing data in text files. Knowledge of regular Expression is also often a difference between a beginner and an experienced programmer. It certainly makes you a better programmer by expanding your knowledge and giving you a powerful tool for searching and troubleshooting.

Top 5 Online Courses to learn Firebase for Beginners in 2025 - Best of Lot

Hello guys, if you have tried creating a web application or mobile app, then you know that it's not always simple, especially if you're not a full-stack developer with years of experience. The good news is that if you don't want to invest time in setting up a full-fledged backend, which is often not required for small apps, then Firebase can really help you. If you don't know, Firebase is an online service from Google (also available via Google Cloud), which provides a real-time database, authentication service, and several other standard backend functionalities. This means you don't need to create a backend of your own, and you can leverage Firebase to quickly ship your mobile apps or web applications.

Top 20 IT Support Interview Questions with Answers for 2 to 3 Years Experienced

Hello guys, if you want to start your career as IT support engineer and  preparing for IT support interview and looking for frequently asked IT support questions from interviews then you have come to the right place. Earlier, I have shared UNIX Interview Questions, SQL Interview Questions as well as Java support engineer interview questions and in this article, I am going to share common IT support questions for 3 to 5 years experienced professionals. If you have worked as IT support engineer then most likely you can answer all of these questions but if you struggle to answer them then I suggest you to first go through a comprehensive IT support course like Google's IT support Professional certification on Coursera to learn and revise key concepts required for IT support engineers. Even beginners can join this course to start their career as IT support engineers. 

Top 5 Courses to learn Linear Algebra in 2025 - Best of Lot

Hello guys, if you want to learn Linear Algebra in depth and looking for best resource slike tutorials and online courses then you have come to the right place. In the past, I have shared best Maths courses and best Statistics courses and in this article, I am going to share best online courses to learn Linear Algebra in depth . Linear algebra serves as a foundational pillar of mathematics and plays a crucial role in various fields, including computer science, physics, engineering, and data analysis. Its applications are vast, ranging from understanding complex systems to solving optimization problems. 

I Took 7 Apache Kafka Courses Online - Here’s Top 5 Which Actually Helped Me?

Hello guys, you might have heard about Apache Kafka, the next generation, Big Data messaging system which is handling billions of messages per day on companies like LinkedIn, Uber, Airbnb, Twitter, etc. It's a revolutionary technology and perfect for today's mission-critical application which has so much data to process and analyze. Since last year, I have been taking a lot of resources like books, courses, and tutorials to learn these sunrise technologies like Apache Kafka so that you can aware of these and learn them to make yourself more valuable or jump into some exciting career path. For example, In the past, I have shared some awesome courses on Big Data, Spark, and Hadoop and many of my readers requested me to share similar suggestions for Apache Kafka.

10 Java Exception and Error Interview Questions Answers

You will always see some interview questions from Exception and Error handling in core Java Interviews. Exception handling is an important aspect of Java application development and its key to writing robust, stable Java programs, which makes it natural favorites on interviews. Questions from Error and Exception in Java mostly based on the concept of Exception and Error in Java, How to handle Exception , best practices to follow during Exception handling etc. Though multithreading, garbage collection, JVM concepts and questions from object oriented design rules these interviews, you should always expect and prepare some questions on effective error handling.

10 Examples of SED Command in UNIX and Linux

SED command in UNIX stands for stream editor and it can perform lots of functions on file like searching, find and replace, insertion or deletion. Though the most common use of SED command in UNIX is for a substitution or for find and replace. By using SED you can edit files even without opening it, which is a much quicker way to find and replace something in the file, than first opening that file in VI Editor and then changing it. In this SED command tutorial, we will see some practical examples of SED commands in UNIX based systems e.g. Linux. I must say having a good grip on the find, grep, sort, vi editors and SED can take you next level of UNIX and Linux working experience.

Why Avoid Comparing Integers in Java using == Operator? Integer Cache Example

Java 5 introduced auto-boxing which automatically converts int to Integer and because of that many Java developers started writing code for comparing int variable to Integer object and Integer to Integer using == operator. You should avoid that because it can create subtle bugs in your program because it only works for a particular range of integers and not for all. There is another problem as well when you compare the int variable to the Integer object using == operator, the Integer object is converted to a primitive value. This can throw a null pointer exception if the Integer object is null, which can crash your program.

How to Create, Update and Remove Soft link in Linux and UNIX - Example

Symbolic links, Symlink or Soft link in Unix are a very important concept to understand and use in various UNIX operating systems e.g. Linux, Solaris, or IBM AIX. Symlinks give you so much power and flexibility that you can maintain things quite easily. I personally feel that along with find, grep and other UNIX commands, the command to create a soft link and update soft link i.e. ln -s is also a must for anyone working in the UNIX machine. Whenever I do scripting or write any UNIX script I always write for symlinks rather than pointing to the absolute path of directories in UNIX.

How to Reverse an Array in Java? Integer and String Array Example Tutorial

This Java tip is about, how to reverse an array in Java, mostly primitive types e.g. int, long, double and String arrays. Despite of Java’s rich Collection API, use of array is quite common, but standard JDK doesn’t have great utility classes for Java. It’s difficult to convert between Java Collection e.g. List, Set to primitive arrays. Java’s array utility class java.util.Arrays, though offers some the critical functionalities like comparing arrays in Java and support to print arrays, It lacks a lot of common features, such as combining two arrays and reverse primitive or object array. 

Top 21 final modifier (keyword) Interview Questions and Answers in Java

The final modifier is one of the important keywords in Java. You can use this with a class, method, and variable as well. Good knowledge of the final keyword is not only essential for writing good, performant, and secure Java programs but also to clear any  Java interview. The interviewer pays special attention to the final keyword and expects candidates to know how and when to use the final modifier with variables, methods, and classes. In this article, I have collected Java interview questions that are based upon the concept of the final modifier. You might have seen many of these questions on both telephonic and face-to-face rounds. 

How to format Decimal Number in Java? DecimalFormat Example

We often need to format decimal numbers in Java like formatting numbers up to 2 decimal places or 3 decimal places or we want to introduce leading zeros in front of numbers. Thankfully Java programming language provides many different ways to format numbers in Java like either using Math.round() or setScale() from BigDecimal but the caveat is that they also do rounding of numbers i.e. 1.6 will be rounded on 2.0 if we use Match.round(). If we are just interested in formatting decimal numbers up to n decimal digits then DecimalFormat is the way to go. java.text.DecimalFormat descends from NumberFormat and provides a dynamic way of formatting numbers in Java.

Introduction to Tibco Hawk for Beginners? Tutorial

Tibco Hawk
This is another short  TIBCO tutorial from my TIBCO tutorial series. in this i am gonna discuss what is TIBCO hawk , Where do we use TIBCO hawk , What are components of TIBCO hawk , what benefit TIBCO hawk offers and how Tibco hawk works.  if you are interested to know more about TIBCO  Rendezvous , TIBCO EMS and there fundamental concept  or if you are looking for some TIBCO Interview questions you may find this link interesting TIBCO Tutorial

What is Repeating groups in FIX Protocol? Example

FIX Protocol repeating group
In this FIX protocol tutorial, I am going to share my experience about FIX repeating block or group. This is a fundamental concept of FIX protocol and used to carry repeating data. A correct understanding of various available FIX repeating groups e.g. PartyID block, Allocation repeating group etc is very important for writing FIX based software. In this FIX tutorial, I will explain about how to parse a repeating group, how to prepare a repeating group and how to understand a repeating group. If you like to know more about basic concepts in FIX protocol then you may find my FIX Protocol tutorial interesting.

Java.net.BindException: Address already in use: JVM_Bind:8080 [Solved]

java.net.BindException: Address already in use: JVM_Bind is a common exception in Java with applications trying to connect on a particular port and some other processes either Java or non Java is already connected on that port. You can get "Address already in use: JVM_Bind" error while doing remote debugging in Java in Eclipse, when Eclipse trying to connect to remote Java application when you are starting tomcat and another instance of tomcat is listening on port 8080 you will get java.net.BindException: Address already in use: JVM_Bind:8080.

10 Examples of chmod command in UNIX Linux

chmod command in UNIX or Linux is used to change file or directory permissions. This is one of many UNIX basic commands which a UNIX or Linux user must be familiar with. In this UNIX command tutorial we will see how to change file permissions using the chmod command, what are file permissions in UNIX, how to change permissions of directory and sub-directory using UNIX chmod command and finally how to create executable files in UNIX using the chmod command. Before going directly into examples of chmod command let's spend a few minutes on understanding file permissions in UNIX and why do we need to change file permissions etc.

Java Tips and Best practices to avoid NullPointerException in Java Applications

A NullPointerException in Java application is the best way to solve it and that is also key to write robust programs that can work smoothly. As it said “prevention is better than cure”, same is true with nasty NullPointerException. Thankfully by applying some defensive coding techniques and the following contracts between multiple parts of an application, you can avoid NullPointerException in Java to a good extent. By the way, this is the second post on NullPointerException in Javarevisited, In the last post, we have discussed the common causes of NullPointerException in Java and in this tutorial,  we will learn some Java coding techniques and best practices, which can be used to avoid NullPointerException in Java.

Insertion Sort Algorithm in Java with Example and Explanation

The Insertion sort is another simple sorting algorithm, which can be used to sort any linear data structure like an array or linked list. On simplicity, this is next to bubble sort, and it’s also pretty close to how humans manually sort something (for example, a hand of playing cards). As the name suggests, the Insertion sort is based upon the insertion of an element in a sorted list. To start, we assume that the first element is already sorted. Then we pick the next element and put it in second place, we compare this number with the first element and if they are not in sorted order, we swap them. This gives a new sorted list of 2 elements.

How to Execute Native Shell commands from Java Program? Example

How to execute native shell commands from JAVA
Though it’s not recommended some time it’s become necessary to execute a native operating system or shell command from Java, especially if you are doing some kind of reporting or monitoring stuff and required information can easily be found using the native command. This is not advised though because then you will lose platform independence which is why we mostly used Java. Anyway, if you have no choice and you want to execute native commands from Java then it's good to know that how we can do it, many of you probably know this but for those who don't know and have never done it, we will see through an example.

TIBCO Rendezvous or TIBCO RV Messaging? Example Tutorial

TIBCO Tutorial:  TIBCO RV messaging
When I started working with a big investment bank I come across a new messaging technology called TIBCO Rendezvous or commonly called as TIBCO RV, I have heard Java Messaging Service (JMS) before but never heard about this TIBCO Rendezvous and it was so extensively used in my application that most of the support issue was caused by this mysterious TIBCO RV. We had several TIBCO Topics also called TIBCO Subjects separate for both Production and Non PRODUCTION environment but still since I don’t have a basic knowledge of this technology I was afraid to do some experiments because there was always a risk to affect the production environment.

10 FIX Protocol Tutorials for Beginners and Experienced Developers and Business Analysts

I have been writing FIX Protocol Tutorial from last few months and today I thought about doing a revision on all those tutorials. It’s very easy to read and forget about anything you have learn so periodic revision is very important and I see its important here as well. In this article I will put summary of each of my previous FIX Protocol Tutorials and give a link back to original article for further reading. This will allow any beginner or new comer to get an idea of what topics from FIX has been already covered in these tutorials and helps them to quickly navigate between those. 

Top 10 Servlet Interview Question Answers for Java JEE Developers

This time its servlet interview questions, I was thinking about what to pick for my interview series and then I thought about J2EE and Servlet is my favorite in that space. Servlet is an important part of any J2EE development and serves as a Controller on many web MVC frameworks and that’s why it’s quite popular on J2EE interviews. These Servlet questions are based on my experience as well as collected by friends and colleague and they are not only good for interview practice but also shows a new direction of learning for anyone who is not very familiar with servlet technology.

How to close telnet terminal in Linux and Windows (quit, exit not working)? Example

The telnet is one of the most useful Linux networking commands, which is used to check if a server is listening on a particular port and it's whether up and running or not, but it's a little bit tricky to use, especially, if you are not using it on daily basis. Though I have used telnet before, when I use it after a long time, I actually forgot how to close the telnet terminal and how to get out of it. I tried every possible  Linux commands I can think of which is used to close, cancel a command, or exit from VIM editor in UNIX, like  Ctrl + C, quit, exit, q! and even the escape character '^]', only to realize that nothing is working. It may sound silly that an experienced developer cannot even come out of a telnet terminal but this is a true story. 

10 Examples to Read a Text file in Java [UPDATED]

The Java IO API provides two kinds of interfaces for reading files, streams and readers. The streams are used to read binary data and readers to read character data. Since a text file is full of characters, you should be using a Reader implementations to read it. There are several ways to read a plain text file in Java e.g. you can use FileReader, BufferedReader or Scanner to read a text file. Every utility provides something special e.g. BufferedReader provides buffering of data for fast reading, and Scanner provides parsing ability. 

Why use PreparedStatement in Java JDBC? Example Tutorial

PreparedStatement in Java is one of several ways to execute SQL queries using JDBC API. Java provides Statement,

PreparedStatement and CallableStatement for executing queries. Out of these three, Statement is used for general-purpose queries, PreparedStatement is used for executing a parametric query, and CallableStatement is used for executing Stored Procedures. PreparedStatement is also a popular topic in java interviews. Questions like Difference between Statement and PreparedStatement in Java and How to prevent SQL Injection attacks in Java are popular java interview questions.

How to encode decode String in Java base64 Encoding? Example Tutorial

Encoding and Decoding of String in Java using base64 are extremely easy if you are using Apache commons code open source library. it provides convenient static utility methods Base64.encodeBase64(byte[]) and Base64.decodeBase64(byte []) for converting binary data into base64 encoded binary Stream and then decoding back from encoded data in base64 encoding mechanism. Many times we need to encode sensitive data be it binary String format transferring over a socket or transferring or storing data in XML files. Though there are other open-source libraries available that provide support to encode any String into base64 like MimeUtil from javax.mail package but Apache commons-codec package is really handy and doesn't add a lot of extra stuff. Its API is also very neat and clean. In this article, we will see how to encode and decode String into base64 encoding.

How to fix DATALOSS Advisory in Tibco Rendezvous or Tibco RV? Example

Understanding DATALOSS Advisory in Tibco Rendezvous
While working with TIBCO rendezvous you guys must have been faced the problem of DATALOSS and might be aware of its severe consequences and in the worst case how it can cause TIBCO Storm (A situation where TIBCO publisher bombards network with publishing so many messages and exhaust all network bandwidth of WAN links resulting in a complete breakdown of network lines and communication).  This Tibco Tutorial is in continuation of my Tibco Tutorial series and in this short TIBCO tutorial I will explain what is DATA LOSS in Tibco and How we can minimize or prevent DATALOSS in Tibco RV.

15 Financial Information Exchange (FIX) Protocol Interview Questions Answers for Experienced

Financial Information Exchange (FIX) Protocol Interview Questions and Answers
Some more Fix protocol interview question , I will put answer along when I'll get some time for now just questions :)  Now I have updated it with answer, Please let me know if you have any doubt, or you have other questions, you can also contribute by any question asked during any FINANCIAL INFORMATION EXCHANGE (FIX)  protocol interview.

How to add or list certificates from keystore or truststore in Java? Keytool Example Tutorial

How to add certificates on keystore in Java is the primary question when you start working on SSL connection and a simple answer is keytool utility in Java is used to add or list Certificates into keystore. SSL is the industry standard for secure communication between two parties e.g. client and server. SSL offers two benefits, it encrypts data transferred between client and server to make it hard for someone to access and understand in between and SSL also verifies the identity of two parties in communication, and certificates are used for that purpose. SSL Setup in Java comes during various processes e.g. Setting up SSL on tomcat, configuring messaging over SSL, or JDBC over SSL are some examples of tasks where you need to deal with keyStore, certificates, and trust stores.

How to Format and Display Number to Currency in Java - Example Tutorial

Displaying financial amounts in the respective currency is a common requirement in Java-based E-commerce applications. For example, if you are selling products on-line globally, you will show price of products in their local currency rather than USD or some other currency. Storing price in every currency is not a good option because of maintenance, and more realistically fluctuation in exchange rates. That's why many of these applications prefer stores price of books, electronic goods, or whatever product they are selling in USD, and the responsibility of converting that price to local currency and displaying is left to client-side code. If your client is a Java-based client e.g. Swing GUI, Java FX client, or a JSP web page, you can use java.text.NumberFormat class to format currency in Java.

5 Example of sort command in UNIX or Linux - Tutorial

Sorting is one of the essential tasks we always need to perform and UNIX or Linux has great support for sorting by using sort command. No matter what kind of shell script you are writing or you are looking for some information or reports many times you need to sort the output of one command or a set of line, with a combination of the sort with find command and grep in UNIX you can handle support request and report quite easily. In this UNIX sort command tutorial, we will see how we can use sort command in UNIX to achieve our sporting goal. This tutorial contains some of the practical example of sort command for sorting data in UNIX. With the use of “unique” and “sort” command, you can remove duplicates and present a sorted data in UNIX.

How to Fix "The system cannot find the path specified." Error in Command Prompt? Example

Recently I was trying to run the Apache Tomcat server from the command prompt to test my Java web application on localhost, only to find the "The system cannot find the path specified" error in command prompt. I haven't seen this error before so I was wondering whether tomcat is throwing or something is wrong with my system's PATH environment variable.  In order to start the tomcat server, I was running the catalina.bat file as tomcat/bin/catalina.bat start and it wasn't starting the Tomcat at all, instead, it was keep throwing "The system cannot find the path specified." error as shown below:

How to Convert char to String in Java? Example Tutorial

There are multiple ways to convert char to String in Java. In fact, String is made of a Character array in Java, which can be retrieved by calling the String.toCharArray() method. Char is a 16 bit or 2 bytes unsigned data type in java mainly used to store characters. You can convert a single character into a String for any purpose in Java in more than one way. I thought about this article while writing how to convert Integer to String in Java but t it took a little longer to get this post completed. In this Java tutorial, we will see different ways to convert a character into a String in java with code Examples.

Difference between TIBCO RVD and RVRD? Rendezvous daemon vs Rendezvous Routing Daemon

RVD (Rendezvous daemon) vs RVRD (Rendezvous Routing Daemon)
RVRD (Rendezvous Routing Daemon) are simply process owned by middleware or network teams which listens to multicast traffic locally and transmit it to another RVRD counterpart (another host) using TCP. This remote host than re multicast this traffic to their own network. So essentially it used to bridge two different regional networks e.g. London and New York etc.

What is FIX Engine in FIX Protocol? Examples

FIX Engine is in the heart of any  FIX protocol-based electronic trading application. W, whenever we discuss FIX protocol we talk about FIX engines, the performance of different Fix engines, support of different FIX versions on FIX engine etc. but on a basic level, we definitely like to know what is an FIX engine and what does FIX Engine do in FIX protocol. In this article, we will try to touch base on such questions with an independent view on FIX engines e.g. What is an FIX engine? Why you need FIX engines? 

Can You Overload or Override Static methods in Java? Example

Can a static method be overridden in Java, or can you override and overload static method in Java, is a common Java interview questions mostly asked to 2 years experienced Java programmers. The answer is, No, you can not override static method in Java, though you can declare a method with the same signature in a subclass. It won't be overridden in the exact sense, instead, that is called method hiding. But at the same time, you can overload static methods in Java, there is nothing wrong with declaring static methods with the same name, but different arguments. Some time interviewer also ask, Why you can not override static methods in Java? The answer to this question lies in the time of resolution.

Error: Could not find or load main class in Java [Solved]

Error: Could not find or load main class HelloWorld comes when you are trying to run your Java program using java command with the main class as HelloWorld but Java is not able to find the class. In order to solve this error, you must know how Java find and loads the classes, that's a little bit complex topic for beginners, but we will touch the same base here. For the curious reader, I would suggest reading my post How Classpath works in Java, a must read for a beginner. For now, you just remember that there is an environment variable called CLASSPATH which includes directories where Java looks for all class files and if it doesn't find your main class there then it throws "Error: Could not find or load main class XXX", where XXX is the name of your main class.

3 Ways to Solve "No JVM installation found. Please install a 64-bit JDK" - Android Studio Example

You are an enthusiastic Java programmer who just learned about developing Android apps in Java. To start with you have installed Android Studio, which is the official Integrated Development Environment (IDE) for Android app development, based on IntelliJ IDEA, but as soon as you click on the Android Studio Desktop Icon to start Android Studio you are getting "No JVM installation found. Please install a 64-bit JDK" error? How do you solve this problem? Well, even though the error message is the same, every problem is different depending upon your machine, the Java version, whether your desktop or laptop has 32-bit or 64-bit OS e.g. Windows 10 or Windows 11. Whether you have installed 32-bit Java or 64-bit JDK e.g. JDK 21.0 and what is the value of the JAVA_HOME environment variable or whether you have defined it or not.

How to find and kill a Process Listening on a port in Linux? netstat and lsof command examples

In Linux, many times, you want to find out the PID of a process that is listening on a port e.g. if multiple tomcat servers are running on a host and you have to kill that process, but in order to kill that process you need the process id, how do you find the PID of the tomcat listening on port 8080? There are many Linux commands to find the process using a specific port, but I'll share what I use. I always use the netstat command with -p option, which displays the process id of the process listening on a port. Btw, netstat is not the only command to find all processes using a particular port, you can also use the lsof command for the same purpose.

2 Ways to Combine Arrays in Java? Integer, String Array Copy Example

There are multiple ways to combine or join two arrays in Java, both for primitive like int array and Object e.g. String array. You can even write your own combine() method which can use System.arrayCopy() to copy both those arrays into the third array. But being a Java developer, I first looked in JDK to find any method which concatenates two arrays in Java. I looked at java.util.Arrays class, which I have used earlier to compare two arrays and print arrays in Java, but didn't find a direct way to combine two arrays. Then I looked into Apache Commons, ArrayUtils class, and bingo, it has several overloaded methods to combine int, long, float, double, or any Object array.

How TIBCO Certified Messaging works? Example Tutorial

This is in continuation of my previous Tibco tutorial. Tibco RV is the most widely used middleware in the enterprise world heavily used in banking and many global investment banks rely on Tibco RV for their high-speed messaging requirements. it's used by many trading applications to receive high-speed data e.g. Market data. in reliable mode Tibco provides reliable delivery of data but not guaranteed means if the sender sends data to the receiver via Tibco multicast network, Tibco tries best to deliver that data to the receiver but there is no guarantee, data could be lost if the receiver is too busy to receive it if the receiver is not running or a receiver is hung. In some cases, it's possible to recover lost data by sending "Resend Request".

How to Replay Messages in FIX Protocol? Example Tutorial

Replaying messages in FIX protocol
In FIX Protocol, two FIX engines communicate with each other using FIX messages and every FIX messages is assign with unique sequence number denoted by tag 34. Apparently every FIX engine has two sequence numbers Incoming Sequence Number (which FIX engine is expecting from a counter party) and Outgoing Sequence Number (which FIX engine is sending to counterparty). This sequence numbers along with rules specified in FIX protocol technical specification ensures that no FIX engine should lose any FIX messages in the event of any disconnect.

Why Catching Throwable or Error is Bad Idea in Java?

We often hear advice that catching Throwable or Error is bad practice and Java developer should avoid catching these, but have you thought Why? If the language allows you to catch anything which is an instance of java.lang.Throwable, then what is the problem of catching them or their subclass java.lang.Error? If they are bad, shouldn't Java itself has prohibited them from catching?  Well, this all looks good on theory, but not in real-world programming. As I said before in Java Exception best practices post, Ideally you should never catch Throwable or in particular Error. 

File permissions in UNIX Linux with Example >> Unix Tutorial

Whenever we execute ls command in UNIX you might have observed that it list file name with lot of details e.g.

stock_options:~/test ls -lrt

total 8.0K

-rw-r--r-- 1 stock_options Domain Users 1.1K Jul 15 11:05 sample

If you focus on the first column you will see the file permissions as "-rw-r--r--" this is made of three parts user, group, and others. The user part is permission relate to user logged in, group is for all the members of the group and others is for all others. also each part is made of three permissions read, write and execute so "rw-" means only "read and write" permission and "r--" means read-only permission.

3 Tips to Fix java.lang.ArrayindexOutOfBoundsException: 1 in Java Programs - Example Tutorial

The error ArrayIndexOutOfBoundsException: 1 means index 1 is invalid and it's out of bounding i.e. more than the length of the array. Since the array has a zero-based index in Java, this means you are trying to access the second element of an array which only contains one element. The ArrayIndexOutfBoundsException comes when your code, mostly for loop tries to access an invalid index of the array. If you have worked in C, C++ then you will notice this difference between array in C and Java. You simply cannot access invalid array index in Java i.e. indexes which are less than zero and more than the length of the array.

How to Check or Detect Duplicate Elements in Array in Java? Example Tutorial

Detecting duplicate elements in Java array is another programming interview question I like. There could be a lot of ways you can check if your array contains duplicate elements or not and sometimes you discover a unique way of checking duplicates by asking this question on Java interview. The beauty of this question is that it has an endless number of follow-up question so if interviewee gets through this question you can ask to him about time complexity and space or to improve his algorithm to make it fast .you can even ask to find those duplicate elements in Array which even can go from one duplicate to many repeating elements in Array. As I said you can really test programming skills around an array of a Java programmer.

How to create and execute JAR file in Java – Command line Eclipse NetBeans Example

Creating JAR file in java from the command prompt is always been little tricky for many of us even if IDE like Netbeans and Eclipse provide support to export java program as JAR file simply because we don’t create jar often and not familiar with manifest file or jar command as a whole. JAR file in Java is a kind of zip file that holds all contents of a Java application including Class files, resources such as images, sound files, and optional Manifest files. JAR stands for Java Archive and provides a platform-independent deliverable for java programs, libraries and frameworks. you can execute the same jar file in any operating system e.g. Windows 7, Windows 8, Macintosh, or Linux.

Difference between Tibco EMS and Tibco RV? Answer

Both of them are products from Tibco and are used extensively across global investment banks for the front end to back end communication or server to server communication. though they have differences in the manner they have designed and the specification they are based upon. Tibco RV stands for Tibco Rendezvous which is based on proprietary Tibco protocol (TRDP/PGM) developed by the company. They have provided API in almost all major programming languages and this is a preferred choice if you need high-speed communication e.g. publishing market data updates etc. 

What is FIX Session and Admin Messages in FIX Protocol? Tutorial

FIX Protocol Session or Admin messages tutorial
I have been working on FIX protocol for almost 5 years when I started working on FIX protocol I looked upon internet for some good tutorial which could supplement or complement lengthy FIX protocol specification there was nothing at that time so when I started my blog I thought to write about my own experience in FIX protocol as short, clear and concise tutorial format. Since I like question-answer type of knowledge sharing too I have written some blog post on FIX protocol Interview questions you may find it interesting. 

What is GET and POST method in HTTP and HTTPS Protocol? Answer

GET and POST method in HTTP and HTTPS are two most popular methods used to transfer data from client to server using  HTTP (Hyper Text Transfer Protocol)  protocol. Both GET and POST can be used to send requests and receive response but there are significant differences between them. The difference between GET and POST in HTTP or HTTPS is also a popular interview question in JSP and any web programming interview. Since HTML is independent of any web server technology like Java, ASP or PHP and HTTP is core protocol in space of the internet, the importance of a clear understanding of GET and POST method can not be ignored.

How to Fix javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException in Java? Example

If you are working in a Java web or enterprise application that connects to any other web server using HTTPS you might have seen the "javax.net.ssl.SSLHandshakeException". This is one of the particular cases of that error. If you know how SSL and HTTPS work that when a Java client connects to a Java server the SSL handshake happens. In these steps server return certificates to confirm its identity, which the client validates against the root certificate he has in its truststore. If Server returns a certificate that cannot be validated against the certificates a browser or Java client holds in its truststore then it throws the "sun.security.validator.ValidatorException: PKIX path building failed:
sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target".

10 Examples of Vim or VI editor in UNIX and Linux

Vim or VI editor tutorial in UNIX 
VI Editor is like notepad in UNIX but it’s extremely powerful and has a sophisticated feature to work as complete IDE. No matter which version of UNIX you are working or which flavor you are using you always find either VI editors or VIM there. VI is a very large topic and I am not covering every aspect of it what I am sharing here is some examples of using VI editor in UNIX or Linux. most of the time we use only 10% of VI editor and never know 90% of it, to be frank, I also don't know many of VI features by heart but I always search for it, see people working in VI and learn from their experience as well.

5 JSTL Core IF Tag Examples in JSP - Tutorial

<c:if>  or if the tag of JSTL core tag library in JSP is one of the most versatile and useful tags. JSTL if tag allows you  to test for a condition, like checking for a particular parameter in requestScope, sessionScope, or pageScope. You can also check any parameter in request parameters and headers or can check for a variable in JSP page using <c:if> tag. JSTL if tag helps a lot to reduce the amount of Java code from JSP  page and if used, along with expression language JSTL core tag library, can remove almost all Java code from JSP files. Earlier we have seen examples of JSTL foreach tag and JSTL core set tag and this JSP JSTL tutorial is based on if the tag of the JSTL core tag library.

Difference between URL-rewriting URL-encoding in Servlet JSP? Answer

URL-rewriting vs URL-encoding in Servlet JSP

The main difference between URL-rewriting and URL-encoding is that URL-rewriting is a technique to maintain user session if cookies are not enabled on the client browser or browser doesn't support cookie while URL-encoding is a way to pass a string to the server containing special characters by converting special characters like space into some other characters like +. People often confuse between URL encoding and URL rewriting because of there names which sound quite similar for new guys but functionality wise they are totally different to each other, Also servlet encodeURL() method adds more confusion because its sounds like its used for URL Encoding but indeed used for URL Rewriting.

Tibco RV Tips and Commands with Examples

This is the third post on series of "Tibco tutorials" , In this article, I am posting some of the most useful commands which I used while working in tibco rv in many application , they are extremely useful and must be in developers top of head who is working in tibco rv.  Before writing these "tibco tutorial" series I looked for some introductory simple TIBCO tutorial which explains concept of tibco rv in simple word and give us working knowledge of TIBCO but I did not found any. TIBCO is most heavily used middleware solution on enterprise world and form backbone of many large enterprise including global banks.

How to deal with Common FIX Session Connection Issues? Solutions

FIX Protocol Session Connectivity
Hi guys, in this post I would like to share my experience with financial information exchange (FIX) Connections which is essential to set up FIX connectivity for trading purposes. Financial information exchange (FIX) Connections are used in both Client Connectivity and Exchange connectivity space (in case exchange supports financial information exchange (FIX) Protocol or you are connecting to any broker via FIX  Protocol).

InOrder traversal of Binary tree in Java using Recursion and Iteration - Example Tutorial

This is the second article about tree traversal algorithms using Java. In the first part, we have seen the pre-order algorithm for visiting all nodes of the binary tree and today we'll learn about the InOrder traversal. As I told you before, unlike array and linked list, the binary tree has several ways of traversal. The traversal algorithms are broadly divided into depth-first and breadth-first traversal algorithms depending upon how the algorithm actually works. As the name suggests, depth-first explores binary tree towards depth before visiting sibling, while breath first visits all nodes in the same level before going to next level, hence it is also known as level order traversal. 

How to Print all Leaf Nodes of Binary tree in Java - Recursion and Stack Examples

Binary tree based questions is very common in Java or any other programming job interviews. One of the frequently asked binary tree questions is "write a program to print all leaf nodes of a binary tree". In order to solve this problem, you must know what is a leaf node? A leaf node in a binary tree is a node whose left and right child is null. They are actually the last nodes of any binary tree. In a typical programming interview, you would be given a binary tree and asked to write a program to print all leaf nodes. Usually, all binary tree related questions can be solved easily using recursion because a tree is a recursive data structure, but you should also know how to solve them without recursion.

Top 10 Maven Plugins Every Java Developer Should Know

In the last couple of years, Maven has become the de-facto build tool for Java applications. Though there are challenges that exist from tools like Gradle, I think the dominance of Maven will help it to win the final battle. When I started with Maven, I was happy with just dependency management but then I come to know about maven plugins which let you customize your build-up to the level you can do with ANT. These plugins provide true power to Maven to automate most of the build-related tasks like compilation, testing, packaging, deployment, and even committing the source code into the remote source repository.