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# How to Find Missing Number in a Sorted Array in Java [Solved]

Today's coding problem is not very new, it's an age-old classic Programming interview Question. You have a sorted array containing n - 1 unique number starting from 0 to n - 1. There is only one number missing in this range and you need to find that out. I mean you need to write a Java method to find the missing number and print its value in the console. Some of you might have seen this question before, but if you have not been asked this question before, what is the first approach comes into your mind to solve this question? Since only one number is missing, many programmers come up with the approach of iterating over the array, and comparing each element with the expected one like the first element should be 0, the second element should be 1, and so on.

# 5 Free Microservice Courses for Java Programmers [Spring Boot + ReactiveJ/RxJava]

Hello guys, if you want to learn Microservice architecture and looking for free Microservice resources like free online courses then you have come to the right place. Earlier, I have shared the best Microservice courses for Java programmers to build Microservice using Java and the Spring framework, and today, I am going to share some free courses to learn Microservice in Java using Spring Boot and the Spring Cloud framework. If you don't know, Microservices is a modern architecture that goes along nicely with cloud computing and makes deployment, scaling, and even development easier.

# 2 Ways to Find Duplicate Elements in a given Array in Java [Solution]

Hello guys, today, you will learn how to solve another popular coding problem. You have given an array of objects, which could be an array of integers and or an array of Strings or any object which implements the Comparable interface. How would you find duplicate elements from an array? Can you solve this problem in O(n) complexity? This is actually one of the frequently asked coding questions from Java interviews. There are multiple ways to solve this problem, and you will learn two popular ways here, first the brute force way, which involves comparing each element with every other element, and other which uses a hash table-like data structure to reduce the time complexity of the problem from quadratic to linear, of course by trading off some space complexity.

# Top 5 AWS Cloud Practitioner Certification (CLF-C01) Courses, Practice Tests, and Exam Dumps - Best of Lot

Hello guys, If you are preparing for AWS Certified Cloud Practitioner and looking for some affordable awesome online training courses and practice tests to start your preparation then you have come to the right place. Earlier, I have shared free AWS Cloud Practitioner courses, and in this article, I am going to share the best AWS Certified Cloud Practitioner certification online training courses for beginners and anyone who want to learn about AWS and Cloud Computing and also want to earn a certification. In this list, I have selected some of the finest courses from Udemy, Whizlabs, and other places that are both tried and trusted and helped thousands of people to pass these prestigious AWS and Cloud certifications. They are also very affordable and you can take all these AWS Cloud practitioner training tests online.

# 40+ Java IO and Files Interview Questions with Answers

Good knowledge of Java IO API is important for any Java developer but many of them barely pay attention to Java IO and NIO API, and that's why they often struggle during Java interviews when a question related to Input-Output operation is asked. In the past, I have shared many Java interview questions on topics like Collections, Concurrency, JVM internals, Garbage Collection, OOP, Design Patterns, and Data structure based coding problems, which received good feedback and helped many Java developer on their Java Interview preparation. Consequently, many of my readers were also asking about Java IO and File-based interview questions and this was one of the pending items on my TODO list for quite some time.

# Top 5 Free Core Spring, Spring MVC, and Spring Boot Courses for Beginners to learn Online

I have been sharing a lot of resources e.g. books and courses recently and when I published my list of Top 5 courses to learn Spring and Hibernate, many of my readers asked about a similar list of free courses to learn Spring Framework like Core Spring, Spring MVC, Spring Security, and Spring Boot. That request was always back in my mind but I couldn't get time to put together a list, which I can share with you guys, but today is the day. In this list, I have compiled some of the best online free courses to learn Spring Framework from scratch, online at your own pace. You can not only learn core Spring like the framework which provides dependency injection, but also Spring MVC, the most important framework for a Java Web Developer, Spring Security, and Spring Boot to take your career to next level.

# A Simple Example to Check if File is Empty in Java

One of the readers of my blog Javarevisited emailed me yesterday about how to check if a file is empty in Java and that's why I am writing this post to show that using an example. The common approach for checking if a file is empty or not is to first check if the file exists or not and then check if it contains any content, but Java has done that hard work for you. Well, it's pretty easy to check emptiness for a file in Java by using the length() method of the java.io.File class. This method returns zero if the file is empty, but the good thing is it also returns zero if the file doesn't exist. This means you don't need to check if the file exists or not.

# Top 5 Spring Security Online Training Courses for Java Developers

Security is one of the most important aspects of a modern web application, be it a Java web application, .NET, or writing using any other web technology. In the Java world, Spring Security rule the security space. It's one of the rare frameworks which provided many security features, like authentication, authorization, session management, remember me, and several other useful features out-of-the-box. Since there was no competition for Spring security and it does its job very well, it soon becomes the de-facto standard for implementing security in both Java web applications, REST APIs, and core Java applications. The rise of the Spring framework certainly helps it to cement its place as well.

# Top 25 Examples of ConcurrentHashMap in Java [Tutorial]

The java.util.ConcurrentHashMap is one of the most important classes of JDK. It was introduced in JDK 1.5 along with other concurrent collection classes like CopyOnWriteArrayList and BlockingQueue. Ever since then, it has been a workhorse in concurrent Java applications. It won't be an exaggeration If I say there is hardly any concurrent Java application that has not used ConcurrentHashMap yet. The class was another implementation of Java .util.Map and a popular hash table data structure with concurrency inbuilt. This means you can also pass a ConcurrentHashMap to a method that is expecting a java.util.Map object. It was made scalable by dividing the whole map into a different segment, known as concurrency level, and then allowing threads to modify segments concurrently.

# 5 Free Linux Courses for Programmers and IT Professionals to Learn Online [2021]

Linux is one of the most popular operating systems to run server-side applications. I have seen almost all Java applications running on Linux, barring a couple of them, which run on Windows as a service. If you take out standalone apps like IDEs or tools, most of the real-world Java applications run on Linux, like payment gateways, trading systems, and other financial applications. That's why it's essential for any programmer, IT professional, or developer to learn and understand Linux, both the operating system, as well as the command line.

Someone asked me the other day,  what are the difference between Polymorphism and Overriding in Java and the similar difference between Polymorphism and Overloading. After explaining to him personally, I thought to write a blog post about it and here we are. Well, they are not two different things, Polymorphism is an object-oriented or OOP concept much like Abstraction, Encapsulation, or Inheritance which facilitates the use of the interface and allows Java program to take advantage of dynamic binding in Java. Polymorphism adds flexibility to your code which makes it more extensible and maintainable.

# 10 Best JavaScript Online Courses from Udemy, Coursera, Pluralsight, and CodeCademy in 2021

Hello guys, JavaScript is one of the most powerful programming languages and if you want to learn JavaScript then now is the best time. If you are looking for the best and advanced JavaScript courses then you have come to the right place. Earlier, I have shared free JavaScript courses and in this article, I am going to share some of the best courses to learn JavaScript in 2021. I have compiled this list by collecting a lot of recommending JavaScript courses from online learning platforms like Udemy, Coursera, Pluralsight, Educative, CodeCademy, edX, Udacity, and others. This is a decent collection of different types of JavaScript courses from different platforms. While you don't need to join all these courses, joining one or two will be enough.

# Default Methods and Multiple Inheritance in Java 8

Ever since Java 8 introduced default and static methods in JDK 8, it's become possible to define non-abstract methods in interfaces. Since Java, one class can implement multiple interfaces and because there can be concrete methods in interfaces, the diamond problem has surfaced again. What will happen if two interfaces have methods o the same name and a Java class inherit from it? Many Java programmer also asks me the question that, is Java 8 is also supporting multiple inheritances of classes? Well, it's not but the doubt is genuine because the interface with methods is similar to an abstract class or in that any Class in Java.

# Top 5 Free Data Science and Data Analysis Courses for Beginners in 2021 - Best of Lot

Hello folks, Data Science and Data Analysis are two of the most in-demand skills in the current technology world and all kinds of companies need them to improve their sales, profit, and overall business process. If you want to learn Data Science and Data Analysis and looking for some free online training courses to start your career then you have come to the right place. Earlier, I have shared the best Data Science courses and In this article, I am going to share free Data Science courses from Udemy and Coursera for both beginners and experienced programmers. You can join these courses to learn Data Science from scratch. They are also good to fill gaps in your knowledge if you already doing Data Analysis, and the big point, they are completely FREE.

# Difference between Set, List and Map in Java - Interview question

Set, List and Map are three important interfaces of the Java collection framework, and the difference between Set, List, and Map in Java is one of the most frequently asked Java Collection interview questions. Sometimes this question is asked as When to use List, Set and Map in Java. Clearly, the interviewer is looking to know that whether you are familiar with the fundamentals of the Java collection framework or not. In order to decide when to use List, Set or Map, you need to know what are these interfaces and what functionality they provide. List in Java provides ordered and indexed collection which may contain duplicates.

# 5 Best Django Online Courses for Beginners to Learn in 2021

Hello guys, if you want to become a Python web developer and looking for the best online courses to learn Django, Flask, and Python web development then you have come to the right place. In the past, I have shared the best Python courses and the best Flask courses and today, I am going to share the best course to learn everything about Python web development. you may know that Python is a multi-purpose programming language meaning that you can use it in different fields such as GUI application, artificial intelligence, and web application, and much more, just to name a few.

# 3 Examples of for loop in Linux and Bash Script [Tutorial]

Hello guys, if you want to learn how to use for loop in bash or Linux then you have come to the right place. Earlier, I have shared free Linux courses and free bash scripting courses, and today, I am going to share three simple examples of using for loop in Linux.  If you are a Programmer, Software Engineer, or System Administrator working in a UNIX or Linux environment, then you will probably find the shell 'for' loop to be a handy tool for automating simple command-line tasks. This is the single command which has helped me a lot while doing production support and performing operational tasks.

# Right way to check if String is empty in Java

What do most of us Java Programmers do while using String in Java? checking whether String is null or empty right? I am sure you know a couple of ways to test whether String is empty or not, but do you know the right way to do it? When we talk about Strings in Java, we can imagine them as arrays of characters, and they are, but in Java, they also object. An empty Java String is considered as the not null String that contains zero characters, meaning its length is 0. However, a Java String that might only contain the white-space character is not considered empty, it is considered to contain one character and its length is equal to 1.

# Top 5 courses to learn Docker for Java and Spring Developers - Best of Lot

Hello Java programmer, if you want to learn Docker and looking for the best Docker Courses from Java and Spring Boto developer point of view then you have come to the right place. Earlier, I have shared free Spring Boot courses as well as free Docker courses and in this article, I am going to share the best Docker courses for Java and Spring developers. Java is one of the most popular and widely used programming languages. It is an evergreen programming language. For Java developers, Docker is a game-changer. Docker is emerging at a rapid speed and it's now one of the most important tools for all kinds of programmers and there are reasons for it like Docker makes both development and deployment easier.

# 12 Advanced Java programming Books for Experienced Programmers - Part 2

This is the second part of 12 must-reads advanced Java programming books for intermediate and experienced Java programmers. In the first part, I have shared books to learn and master concurrency, performance, design patterns, and Java collection framework, which is essential for every Java developer irrespective of experience. On the other hand, In this article, I will talk about more advanced concepts, like security, Java 8, best practices, etc., which are more important for senior Java developers. As an experienced Java developer, a lot is expected of you. Junior developers look at you for guidance, and project managers look at you to solve problems and bail them out at critical junctures.

# Is it Possible to add static or private methods in Java interface?

Can you add a static or private method in an interface in Java? or is it possible to add a private or static method in Java interface? or can you add a non-abstract method on an interface in Java? are a couple of popular Java interview questions which often pop up during telephonic interviews. Well, prior to Java 8, it wasn't possible to add non-abstract methods in Java but nowadays you can add non-abstract static, default, and private methods in the Java interface. The static and default methods were supported as part of interface evolution in Java 8 and you can add private methods on an interface from Java 9 onwards.

# 5 Free Cloud Computing Courses for Beginners to Join in 2021 [Best of Lot]

Hello guys, if you want to learn Cloud computing in 2021 (which is really great!!) and looking for the best free resources like online courses to kick start your Cloud Computing journey then you have come to the right place. In the last, I have shared free courses to learn AWS, Google Cloud, and Microsoft Azure, and today, I am going to share free Cloud Computing courses for beginners. Cloud Computing is an essential skill for the modern developer as most of the new development is happening on Cloud and will happen in the cloud. If you are not familiar with how the cloud works and with essential Cloud concepts and terminology like IaaS, PaaS, SaaS, compute, storage, network, etc then you are at risk of left behind.

# Top 10 Cloud Certification (AWS, Azure, and GCP) You can Aim in 2021 - Best of Lot

Hello guys, if you are aiming for cloud certifications in 2021 but not sure which cloud certification should you go for then you have come to the right place. Earlier, I have shared a list of the best IT certifications for Java developers, and today, I am going to talk about the best cloud certification to aim for in 2021. You can go through this list of cloud certifications and choose the best one depending upon your skills and experience. I have shared the best cloud certifications for beginners, developers, system admins, and solution architects from Amazon AWS, Microsoft Azure, and Google Cloud Platform.

# 70+ Java Interview Questions for Beginners [1 to 2 Years Experienced]

Java Developer Interviews are very different than traditional software developer interviews. You can clear a Java interview without even writing a single line of code, Yes, this is true, you can become a Java developer without someone asking you to write a function in a Java interview. Though it's not the case everywhere and many companies are increasingly including a coding test in their Java developer interview process, but there are many companies and start-ups where you can get a Java job without writing a single line of code. All you need to do is learn those popular Java questions, which have been asked for ages, and mostly test whether a candidate is familiar with essential Java concepts or not like abstract class and interface.

# 13 Best Java Serialization Interview Questions and Answers for Beginners

There is no doubt that Java is vast and there are some Java topics which many Java developers rarely explore in work but they are important from a Java interview point of view. Serialization is one of them which is rarely used in practice but quite popular during Java interviews. It's also one of the difficult topics to master and that's why I am going to share some frequently asked Java Serialization interview questions in this article.  I don't know why people ask so many questions from Selrization if not everyone uses it but I have always seen some questions from Java realization. These are also the toughest and confusing questions to answer and more likely cannot be answered by an average Java developer.

# 5 Free Ethical Hacking courses for Beginners to Join in 2021

Hello folks, if you want to learn Ethical Hacking and looking for free online courses then you have come to the right place. Earlier, we have shared the best Cyber Security Courses, and today, we are doing share free Ethical hacking courses for you. Most of us have even a little bit of knowledge about the subject or industry that would be ideal if you start a career in that field but the problem for most people is finding the right course or program that help you master these skills and become professional in the field and click on this article likely shows that you are interested in ethical hacking.

# Java Serialization Example and Tutorial for Beginners [Guide]

Serializing an object in Java is never easy and many Java developers often get confused. There are so many rules, interfaces to implement, and then always a chance of data loss or an error during the Serialization or deserialization process.  In the past, I have posted a detailed guide of Serliazing Object in Java which is very liked by my readers and they asked for more information like what should Java developer remember while using Serializable and Externalizable interface in Java. This encouraged me to write this post where I have put together 10 important points related to Serializing an Object in Java. This is a to-the-point article that is full of information and I have also shared a core example to demonstrate the point I have mentioned in this article.

# How to use DROP command to remove tables in Oracle, MySQL and SQL Server

Hello guys, if you want to learn about DROP command in SQL then you have come to the right place. Earlier, I have shared the best free SQL and Database courses and several tutorials to learn SELECT, GROUP BY, and other important commands, and in this article, I will show you to use the DROP command in SQL. DROP is one of the basic SQL commands, which is used to DROP database objects. Since it's part of ANSI SQL, the DROP command is supported by all major database vendors, including Oracle, MySQL, and Microsoft SQL Server. A SQL DROP TABLE statement is used to delete a table definition and all data from a table, but DROP can also be used to drop index, view, trigger, or any other database object.

# How to Pass AWS Certified Solutions Architect: Associate SAA-C01 & SAA-C02 Exams [Resources]

Hello guys, If you are preparing for the AWS Certified Solutions Architect Associate Exam then you can find several articles online about the AWS Solutions Architect Associate exam and preparation. But it's not easy to keep all the good content or bookmark them all. However, it takes time to find all the right content and keep it safe for reading and learning more. We understand the value of your time and effort at the time of the exam, so here we present all the content related to the Associate AWS Solutions Architect exam in one place so that you can start your preparation in a structured way.

# Top 5 Free Google Cloud Platform Courses for Beginners in 2021 - Best of Lot

Hello guys,  If you also want to learn Google Cloud Platform in 2021 and looking for some free online Google Cloud training courses and materials to start your GCP journey then you have come to the right place. Earlier, I have shared the free Google Cloud Developer certification courses, and today, I am going to share free online courses from Udemy and Coursera which you can join to learn Google Cloud platform. If you don't know, Google Cloud Platform is the massive Cloud platform for Google which is one of the three biggest public cloud platforms along with AWS and Microsoft Azure

# How to Schedule Spring Professional Certification Exam (VMware EDU-1202) Online?

Hello folks, even since Pivotal made the mandatory training optional for Spring certification, I have been writing a lot about Spring 5.0 Core Professional exam here. In the past, I have written about general preparation tips, books, coursesmock tests. So, after months of hard work and preparation, you are finally ready for the day. In order to schedule for the Spring certification exam, you first need to buy an exam voucher from Vmware's website. If you have taken their training course like the Core Spring training course, then you also receive a free voucher for 1 attempt.

# How to use InstanceOf keyword in Java [Example Tutorial]

The Java programming language and JVM are full of hidden gems and even though I am using Java for more than a decade I still get surprised by features that I didn't know for quite some time e.g. shutdown hook, covariant method overriding, and JVM option to refresh DNS cache.  The instanceof operator is also one of the rarely known features of Java, It is used to check if an object is the instance of a particular class or not. It returns true if the object is an instance of the class, otherwise, returns false. You might have seen usages of the instanceof keyword in Java while overriding the equals() method. Since for checking equality of two instances, the first step is to verify whether they are the instance of the same object or not, you can use the instanceof operator there.

# Top 5 Online Courses to learn Responsive Web Design in 2021 - Best of Lot

Hello folks, Responsive web design is one of the essential skills to become a front-end web developer, a web designer, and even a full stack developer. If you are interested in learning Responsive web design and looking for the best online training courses then you have come to the right place. In the last few articles, I have shared the best courses to learn UI/UX design, HTML 5, CSS 3, and Photoshop for FREE and in this article, I am going to share the best online courses to learn Responsive web design.  These courses have been created by experienced web designers and developers and thousands of programmers and developers have trusted this course to learn responsive web design you can also join them to learn this in-demand skill from your home.

# 5 Advanced Books for Experienced Java, C++, Python, Ruby and JavaScript Developers

It's one thing to know about the syntax and semantics of a programming language and other things to use it effectively. If you are a programmer and want to take your programming skill to next level in your choice of programming language, and looking for the best resources then you have come to the right place. Earlier, I have shared the best online courses to learn Python, Java, JavaScript, and C++, and today, I am going to share advanced programming books for experienced Java, C++, Python, Ruby, and JavaScript developers. To be honest, there are several books that will be taught you about the syntax and grammar of a programming language, but there are really few books that will teach you the customary and effective ways to use it, also known as idiom and usages.

# Difference between 32-bit vs 64-bit JVM in Java?

Hello Java Programmers, if you want to learn Java virtual Machine in-depth and wondering what is the difference between a 32-bit and 64-bit JVM and which one should you use and why? then you have come to the right place. Earlier, I have shared the best JVM books and online JVM courses and in this article, I am going to talk about 32-bit vs 64-bit JVM and their pros and cons. This is also a common Java interview question for beginners and intermediate Java programmers. I have tried to answer this question to the point that's why this article is a short but informative one. You will find out what they are, how they are different, how much heap size, and the pros and cons of each of them.

# Top 5 Books and Courses to learn C and C++ Programming in 2021 - Best of Lot

Hello there, If you want to learn C or C++ and looking for the best books and online courses then you have come to the right place. Earlier, I have shared free C programming courses and free C++ courses and today, I am going to share the best books and online courses to learn C and C++ programming language from scratch. If you are just starting out with computer programming but not sure which programming language to choose then you are not alone, we have all faced this problem before and new programmers are facing it every day. That's why starting with a basic programming language like C Programming language is the best decision you can make and I am saying this with my 15+ years of experience in C, Java, and software development.

# Top 5 Free Courses to learn Salesforce in 2021 - Best of Lot

Hello there, If you want to learn the Salesforce platform and looking for some free online Salesforce courses then you have come to the right place. Earlier, I have shared the best online courses for  Salesforce DeveloperAdministrator, and App Builder certification, and today, I am going to share free Salesforce courses beginners can use to learn this highly useful platform and add an in-demand skill to their resume. The Salesforce platform is a unique platform for custom application design, analytics features, and new features.

# 7 Top Paying Programming Languages You Can Learn in 2021 for Higher Salaries

Since last a couple of the week, I have been doing some research about which programming languages beginners and experienced developers can learn in 2021 to increase their pay and packages when I stumbled about StackOverflow's Developer Survey. If you have seen them before and it's one of the best surveys for software developers, which provides useful insights about programming and the IT world. One of the things I really like about this survey was its several lists like the list of top 10 programming languages and the most loved frameworks by programmers. Still, the one I found most useful was the list of high-paying technologies. This is a great list and allows you to choose what you can learn in 2021 to go to the next level in your career in terms of both financial and career growth.

# Coursera's Applied Data Science with Python Certification Review - Is it worth it?

If you are thinking to join Data Science with Python Specialization on Coursera but thinking whether it's worth your time and money or not then you have come to the right place. Earlier, I have shared the best Coursera courses for Data Science, and today, I will review one of the most popular Data Science specializations on Coursera. If you have been learning online then you may know that  Coursera is one of the giant platforms out there that offers courses in many different industries from web development and IoT to business and self-development and all those courses are created by major universities such as Michigan University and some companies like IBM which means you are in good hands when enrolling in some of their courses.

# ContextLoaderListener - Spring MVC Tutorials for Beginners [UPDATED]

The ContextLoaderListner is one of the essential components of the Spring MVC framework, probably the most important after the DispatcherServlet itself. It is used to create the root context and responsible for loading beans, which are shared by multiple DispatcherServlet like beans related to the service layer and data access layer. In general, When you develop Spring MVC based web applications and also using Spring in the services layer, you need to provide two application-contexts. The first one is configured using ContextLoaderListener, and the other is set using DispatcherServlet. The DispatcherServlet is responsible for loading web component-specific beans like controllers, view resolvers, and handler mappings while, as I said before, ContextLoaderListener is accountable for loading middle-tier and data-tier beans which forms the back end of Spring applications.

# Top 5 Next.js and React.js Framework Courses to learn in 2021 - Best of Lot

If you are using JavaScript and React or follow web development news then you may know about Next.js, a popular React framework that helps in server-side rendering which improves the user experience of page load ties. Using Server-side rendering also gives you an edge on SEO with a more easily indexable and crawlable website out of the box. The Next.js is touted as the next big thing in the web development world and 2021 may be a good time to learn Next.js. If you want to learn Next.js and looking for some excellent resources like books, tutorials, courses, and guides then you have come to the right place. In the past, I have shared the free React courses and books for beginners and In this article, I am going to share some of the best online training courses to learn Next.js from scratch.

# What is difference between Heap and Stack Memory in Java JVM

One of the many traits of a good programmer is how well he understands the fundamentals and if you want to check the fundamentals of a Java programmer then asking the difference between heap and stack memory is a good choice. Even though both are part of JVM and both consumer's memory allocated to the Java process, there are many differences between them like Heap memory is shared by all threads of Java application but Stack memory is local to each thread. Objects are created in heap memory but method frames are stored in Stack memory, and the size of heap space is much bigger than the small size of Stack in Java.

# Top 5 Free Python 3 Courses for Beginners to Learn in 2021 [UPDATED]

Hello guys, If you are a beginner looking for some Free Python resources to start your programming journey, then you have come to the right place. Earlier, I have shared a couple of free Python Programming books and some of the best courses to learn Python, which were not free. Some of my readers asked me to share some free online courses to learn Python, and it made sense. I personally like starting from free resources, and today, I'll share a couple of excellent Python programming courses, which are absolutely FREE. You can take these online courses to learn Python at your own pace, at your own time, and at your place. This is an excellent advantage of online learning, the flexibility it provides is just impressive.

# Top 5 Free Mongo DB courses for Beginners to Join in 2021 - Best of Lot

If you want to learn MongoDB in 2021, one of the most popular NoSQL databases,s and looking for free resources like free tutorials and free online MongoDB courses to start with then you have come to the right place. Earlier, I have shared the 10 free full-stack development courses and today, I am going to share the 5 best free online courses to learn Mongo DB online. These courses are created by experts and made free for educational purposes. Thousands of students have already joined these free Mongo DB courses and you can also do the same to learn this in-demand skill and further boost your resume for cutting-edge jobs.

# Difference between GET and POST Request in HTTP and REST APIs

HTTP Protocol supports many methods to retrieve data from the server or perform any operation on the server, like upload data, delete the file, etc. In total, the HTTP protocol supports the following methods, GET, POST, PUT, DELETE, HEAD, DELETE, OPTIONS, and TRACE, and the HTTP 1.1 reserves technique called CONNECT for future use.  GET, and POST is two of the most common HTTP methods you would hear or work on the web. Though both can be used to send and receive data from client to server, there are some crucial differences between the GET and POST in HTTP, which will help you to understand when you should use GET vs. POST while writing your client and server application.

# Top 5 Free Docker Courses for Java Programmers and DevOps Engineers - Best of Lot

If you are an application developer working in Java, Python, JavaScript, C#, or any other language and want to become a DevOps engineer or someone who wants to learn Docker, then you have come to the right place. In this article, I am going to share some of the free Docker courses you can use to take online to learn Docker by yourself. These courses are great for both beginners and intermediate developers who have basic ideas about Docker. If you don't know what a Docker is and how it works, then let me give you a brief introduction.

# How to Send HTTP Request from a Java Program - Example Tutorial

If you are thinking is it possible to send an HTTP request from a Java program and if yes, how to send a simple HTTP GET request in Java, then you have come to the right place. In this article, I'll show you how you can use the HttpURLConnection class from the java.net package to send a simple HTTP request in Java. But, first, let me answer your first question, is it possible to send an HTTP request in Java? Yes, it's possible and you can send any kind of HTTP request like GET, POST, PUT, DELETE, HEAD, or PATCH. The java.net package provides a class called HttpURLConnection, which can be used to send any kind of HTTP or HTTPS request from Java program.

# Top 5 Courses to become a Software Tester and QA Analyst in 2021 - Best of Lot

Hello guys, if you want to learn Software testing, both manual and automation testing, and looking for the best online courses to master this skill then you have come to the right place. In the past, I have shared the best and free online courses to learn essential automation testing tools like Selenium, Appium, and JUnit, and today, I am going to share the best courses to learn Software testing in general and start your career as a Software tester or Quality Analysts (QA).  These are the best online courses from sites like Udemy, Pluralsight, Coursera, and edX. It's a combination of both free and paid courses as edX and Coursera courses are free for learning and you only need to pay if you want certification.

# Top 5 Spring Certification Books and Courses for Java Developers - Best of Lot

If you are preparing for Spring Professional certification (VMware EDU-1202) and looking for the best books, online courses, and practice tests for your preparation then you have come to the right place. As an author of a Java blog and a medium publication, I often receive questions about how to self-prepare for a technical certification like Spring Professional v5.0 certification from Pivotal, and which are the best books and courses to prepare for Spring Core certification? After answering a couple of my readers over Facebook chats and linked in, I decided to jot down my recommendations. Books, Online Courses, Study Guides, and Practice tests are some of the important resources to prepare for Spring certifications.

# Top 5 Online Courses to Learn Flexbox, Grid, and Advanced CSS for Web Designers in 2021

Along with HTML and JavaScript, CSS is one of the core technologies of the World Wide Web (WWW) and critical skills for anyone who wants to start their career in web design and web development. No website in the modern world is complete without CSS and it is safe to say, no one can become a complete web developer without CSS. If you want to learn advanced CSS concepts like Flexbox, Grid, and Saas and looking for the best online courses then you have come to the right place. In the past, I have shared some free courses to learn CSS basics and Bootstrap, one of the most popular CSS frameworks for styling web pages, and today I will share advanced CSS courses to learn Flexbox and Grid.

# Is it Possible to take Spring Professional v5.0 Certification without the Official Training course?

Just a couple of years ago, It wasn't possible to take Spring Professional certification without a mandatory expensive training course from Pivotal, but from 10th May 2017 onwards, you can take Spring Certification without a training course. Yes, you read it correctly, it's now possible to become Spring certified developer without spending USD 3200 on mandatory Spring training, like the Core Spring training. For years, Pivotal, the company behind the Spring framework (now Vmware) ensured that a Java developer can only get a Spring Professional certification by first going into a 4-day training run by Pivotal and its partner around the world.

# Top 5 Courses to learn Web Scraping using Python and JavaScript in 2021 - Best of Lot

Hello guys, if you want to learn Web Scrapping and looking for the best online courses to learn Web Scrapping using Python and other programming languages then you have come to the right place. Earlier, I have shared the best web scraping tools and best scrappy courses and in this article, I am going to share the best online training courses to learn Web Scrapping using NodeJS, JavaScript, Python, and BeautifulSoup. These are the best courses from sites like Udemy and Pluralsight which are the best places to learn online. So what is Web Scraping? Web scraping, also known as web harvesting, is a technique used to extract large amounts of data from websites. How does this happen?

# How to Prepare for Vmware Spring Professional v.5.0 Certification Exam in 2021

Hello guys, If you have been doing Java development then you may know the benefits of the Spring Framework that make it one of the best Java frameworks in the community. As an open-source framework, Spring offered the opportunity to build applications on the Java Enterprise Edition platform. First introduced in October 2002, Spring Framework obtained a recent stable release in the form of Spring v5.0 which brought things like Reactive programming and WebFlux. There is a huge demand for Java developers with Spring experience, in fact, Spring is often considered as the most important skill while hiring Java developers and many companies prefer to hire those candidates who have Spring Professional certification in their resume.

# Difference between trustStore vs keyStore in Java SSL

If you are confused between truststore and keystore and looking to find what exactly they mean then you have come to the right place. Earlier, I have shared free Java courses and today, I am going to tell you the difference between trustStore and keyStore in Java. Both trustStore and keyStore are important but confusing concepts and constantly tormented Java developers when they connect to servers using SSL. The main difference between trustStore vs keyStore is that trustStore (as the name suggest) is used to store certificates from trusted Certificate authorities(CA) which are used to verify certificate presented by Server in SSL Connection while keyStore is used to store the private key and own identity certificate which program should present to other parties (Server or client) to verify its identity.

# How to Prepare for Java Certifications like OCAJP, OCPJP, or Java SE 11 Developer?

No doubt that Oracle's Java certification is one of the most valuable certifications for the IT industry and helps you to get a better job, better pay, and a better rise in your current salary. It also improves your recognition and job prospects because many big clients demands certified Java programmers for their mission-critical applications. Because of enormous popularity and usefulness, many Java developers and computer science graduates aspire for Java certifications. I often receive queries like, what is the best way to prepare for Java certifications like OCAJP or OCPJP?

# 7 Examples of HttpURLConnection in Java - Sending GET and POST Request

If you want to learn how to send GET and POST requests from the Java program then you have come to the right place. Earlier, I have shared free Java Courses for beginners, and today, I am going to show you how to use HttpURLConnection class in Java to send HTTP requests to the server.  The HttpURLConnection is an important class in the java.net package which allows you to send an HTTP request from a Java program. By using this class you can send any kind of HTTP request like GET, POST, PUT, DELETE, HEAD, etc to the server and call REST APIs.

# Decorator Design Pattern Example in Java [Tutorial]

The Decorator design pattern is one of the famous Gang of Four (GOF) structural design patterns, which provides a dynamic way of extending an object's functionality. It's different than the traditional way of adding new functionality into an object using Inheritance, instead, it uses Composition which makes it flexible and allows the addition of new functionalities at the run time, as opposite to Inheritance, which adds new functionality at compile time. Because of this flexibility, Decorator is one of the darling patterns for many Java developers.

# Top 5 Free Courses to Crack AWS SysOps Administration Associate Certification Exam

Hello guys, if you are preparing for the AWS SysOps Administrator Associate certification exam and looking for free online courses then you have come to the right place. In the past, I have shared the best AWS SysOps Courses and Practice tests, and today I am going to share 5 free online courses you can join in 2021 to prepare for this prestigious AWS SysOps Certification. Being a regular system administrator might give you enough exposure, but if you have proper certification, then you’ll be getting at least twice the exposure. Since you are here looking for free courses to pass AWS SysOps Administrator Associate Exam, you are no doubt interested in getting a certificate.

# 6 Advanced Linux command Examples for Developers and DevOps Engineers

Hello guys, Linux is an important skill for any developer or DevOps engineer becuase most of the server-side applications run on Linux boxes. At least you should be familiar with essential Linux commands like ls, cat, ps, top, find, grep, awk, sort, uniq, kill, xargs, curl, lsof, etc. I have shared a lot of useful Linux tutorials in this blog and you can take a look at them to learn about those commands in detail. Today, I am going to share some of the useful Linux one-liners you can use in your day-to-day life. These one-liners are either example of one single command or multiple commands used together to do a certain task like finding duplicate rows in a text file or counting how many times each IP address appear in a text file, much like group by clause of SQL.

# OCPJP 11 or OCAJP 8? Which Java Certification should You Take in 2021?

Java certification is a great way to learn and master the Java programming language, do well on the interview and get recognition in the job, but the most common reason for doing Java certification is to find a job. After Oracle's acquisition and dividing the old SCJP exam into two exams OCAJP and OCPJP, it had become really confusing for many developers to decide which Java certification exam they should take, but thankfully that has changed now and now you can become an Oracle certified Java professional by passing just one exam, OCPJP 11 or Java SE 11 Developer 1Z0-819 certification in 2021.

# 10 Object Oriented Programming Fundamental Concepts Every Java Programmer Should Learn

Object-oriented programming (OOP) is a programming style that is used to solve the problem by thinking in terms of real-world objects like Car, Bag, Animal, etc. It also helps you to organize code, which makes it easier to understand and solve complex programs. Objects hold information about state and behavior. States are the characteristics of the object, or the words you would use to describe it, and usually, take the form of is or has descriptors. A computer is either on or off, a chair has four legs, and you have a name. Behaviors are the things the object can do, or the actions the purpose can perform and are usually verbs that end in ing like You are sitting, using a computer, and reading this article.

# How get and put methods of HashMap or Hashtable internally works in Java [Answered]

In this article, I am revisiting a couple of interesting questions related to the internal working of HashMap in Java, mostly asked senior Java developers, ranging from 4 to 6 and up to 8 years of experience. I did cover a lot of these questions from HashMap, ranging from thread-safety to race conditions, in my post about the internal working of Java HashMap, but I thought to revisit two of those questions, how does get and put method of HashMap or Hashtable works internally in Java and what happens if two different keys return the same hashCode, how do you return value from HashMap in that case.

# Top 5 Books for Java 8 Certifications - 1Z0-808 (OCA) and 1Z0-809 (OCP)

If you are preparing for Oracle's Java SE 8 certification then you may know that in order to become a Java 8 Certified developer, you need to pass two exams, the OCAJP 8 exam with code 1Z0-808 and the OCPJP8 exam with code 1Z0-809. You will not be a Java SE 8 certified programmer if you just pass the OCAJP8 exam. In order to prepare for both these exams, you need to choose an excellent study guide, a couple of quality online courses, and a unique mock exam simulator, apart from writing programs on a daily basis. This is the perfect recipe to crack Oracle's Java certification in the first attempt. It requires a lot of hard work but it's worth it.

# 10 Examples of HashMap in Java - Programming Tutorial

The HashMap in Java is one of the most popular Collection class among Java programmers. After my article on How HashMap works in Java, which describes the theory part of Java HashMap and becomes hugely popular among Java programmers, I thought to share how to use HashMap in Java with some fundamental HashMap examples, but couldn't do that earlier and it was slipped. The HashMap is a data structure, based on hashing, which allows you to store an object as a key-value pair, an advantage of using HashMap is that you can retrieve objects on constant time i.e. O(1) if you know the key.

The internet is full of good things, and one of them is free eBooks and PDF. Programmers can almost run anything by these free books. Earlier I have shared some of the free JavaScript tutorials, and in this article, I am going to share 5 good books to learn JavaScript, which are open to read online or allow you to download PDF for offline reading. JavaScript is probably another language I recommend someone who knows Java, Why? Because it's really ubiquitous. There is almost no website that is not using JavaScript in one or another format.

# How to check if a Key Object Exists in HashMap Java? containsKey() Example

Hello guys, you might know that one of the common programming tasks while using HashMap in Java is to check if a given key exists in the map or not. This is supposed to be easy, right? Yes, it is easy if you know your API well, all you need to is call the containsKey() method, it returns true if the given key exists in HashMap, otherwise false; but I have seen many programmers write code like below which is not correct, which inspired me to write this blog post.

if(map.get(key) !=  null){
System.out.println("key exits in Map");
}

This code is fragile, it will not work if you have added null values into HashMap because HashMap does allow null values.

# 5 Free Online Courses for AWS Solution Architect Professional Exam - Best of Lot

Hello folks, if you are preparing for the AWS Certified Solution Architect Professional exam and looking for some free online courses then you have come to the right place. In the past, I have shared free and best online courses to prepare for  AWS Cloud Practitioner, AWS Developer, AWS Architect Associate, and SysOps Administrator certification, and today I am going to share free online courses to prepare for the AWS Solution Architect Professional certification exam in 2021. The AWS Solution Architect Professional Exam is one of the most reputed and most challenging AWS certification exams. For this exam, you have to be ready enough to answer questions from any corner of AWS.

# 10 Programming questions and exercises for Java Programmers

If you have just started learning the basics of Java programming language or familiar with programming in either C or C++, then these Java programming questions and exercises for you. It doesn't focus on a particular part of Java, but these coding exercises will switch you into programming mode. These are also great ways to master basic programming construct like if-else, loops like for and whileJava operators e.g., arithmetic and logical operator, recursion, methods, or functions, and standard Java API. You may also find these Java programming questions in most Java courses taught in schools, colleges, and various Java training courses.

# Top 5 Books to Learn Groovy and Grails for Java Programmers - Best of Lot

If you want to learn Groovy and Grails and looking for the best resources then you have come to the right place. Earlier, I have shared some of the must-read Groovy books, and today, I'll share some of the best books to learn Grails for Java developers. Grails is a web application development framework completely written in Groovy. The Grails and Gradle framework are built using the Groovy language. Grails is the framework to develop a web application using Groovy. The concepts within Grails, like interceptors, tag libs, and Groovy Server Pages (GSP) are very similar to what we have in Java.

# How to Count number of 1s (Set Bits) in a binary number in Java [Solved]

Good morning folks, In today's article, we are going to discuss one of the frequently asked bit manipulation-based interview questions, how do you count the number of set bits in a given bit sequence?  Bit Manipulation is an important topic in programming interviews and a good programmer should have sufficient knowledge and skill to work with binary numbers. This kind of question tests the skill of the programmer. Sometimes, it is also asked as to how to count the number of 1s (ones) in a given number? Both are the same question because 1 is also known as set bit.  For example, if the given input is 1000110010 then your program should return 4, as three are only four set bits in this bit sequence.

# Top 5 JavaScript Design Patterns Courses for Experienced Web Developers - Best of Lot

If you are a JavaScript web developer and want to learn design patterns to further improve your coding and development skills and looking for the best design pattern courses in JavaScript then you have come to the right place. Earlier, I have shared the best JavaScript courses for beginners, and today, I am going to share the best courses to learn Design Pattern in JavaScript from Udemy, Pluralsight, Udacity, and LinkedIn Learning. These are truly great online courses that you can join to learn this useful skill and become a better JavaScript developer.

# How to Find the Largest and Smallest of Three Numbers in Java? [Solved]

Hey Java programmers, I have been sharing coding problems from interviews for quite some time and today I am going to share with you another interesting coding problem for beginners, how to find the largest and smallest of three numbers. If you are learning how to program or looking to improve your problem-solving and coding skills then these kinds of small problems are good to start with. They not only provide you an opportunity to think about how to solve a problem using basic programming constructs like conditionals (if, else, if-else, switch), loops (for, while, do-while), operators like arithmetic, bitwise and logical operator as well as teach you how to write functions, class and create a program which you can run.

# 5 Free Courses to Crack GCP Professional Cloud DevOps Engineer Exam in 2021

If you are preparing for Google Cloud Professional DevOps Engineer certification  in 2021 and looking for free online Google cloud DevOps Engineer courses then you have come to the right place. In the past, I have shared the best Google Cloud courses and best DevOps Courses,  as well as the best online training courses to pass cloud engineer, data engineer, and cloud architect certifications, but my readers kept asking for free online courses on Google Cloud, particularly for DevOps engineer certification, and today, I am going to share free GCP Cloud DevOps Engineer certification courses for both beginners and experienced cloud professionals.

# 80+ Core Java Interview Questions for 1 to 3 Years Experienced Professionals

Hey Java programmers, if you are preparing for a Core Java interview and looking for some frequently asked Java interview questions for quick revision then you have come to the right place. Earlier, I have shared the best books and best courses for Java interviews.  I have also shared many posts about Java Interview Questions and in this article, I will share Java Interview questions and answers especially for junior Java programmers, someone with 1 to 3 years of experience. This includes college graduates, who are looking for the job, Java programmers who have 1 to 2 years of experience in Java, and junior developers who have 2 to 3 years of experience in Java, C++, etc.

# How to Implement a Power Function in Java - Coding Interview Question

If you are preparing for a coding interview and wondering how to implement a function to calculate the power of x to y then you have come to the right place. Earlier, I have shared the best books, websites, and courses for coding interviews and in this article, I will show you how to solve this common coding problem from interviews with companies like Amazon, Flipkart, Google, and startups, and in this article  Even though the Java library has a power function Math.pow() to calculate the power of a given number in Java, it's a regular programming exercise for Java programmers to implement a power function.

# Top 5 Courses & Practice Tests to Crack Professional Scrum Master (PSM) Certification in 2021

If you want to become a Scrum Master and grow your career, or preparing for Scrum Master Certification (PSM) in 2021 and looking for the best Scrum courses, classes, books, and tutorials then you have come to the right place. Earlier, I have shared the best Agile & Scrum courses and books, today, I am going to share the best online courses you can join for Scrum Master Certification in 2021. These courses have been chosen from popular learning websites like Udemy, Pluralsight, and Edureka and they are created by experts who have also gone through the same path and already certified Scrum Master. I have also include PSM practice tests which are very important to build the speed and accuracy required for a time-based exam.

# Counting Sort in Java - Example

The Counting sort algorithm, like Radix sort and Bucket sort, is an integer-based algorithm (i.e. the values of the input array are assumed to be integers), non-comparison, and linear sorting algorithm. Hence counting sort is among the fastest sorting algorithms around, in theory. It is also one of the few linear sorting algorithms or O(n) sorting algorithms. It's quite common in Java interviews nowadays to ask, whether do you know any O(n) sorting algorithm or not. If you face this question in the future, you can mention Radix sort, Bucket sort, or Counting sort algorithms.

# Top 5 Online courses to learn Adobe Premiere Pro + After Effects in 2021 - Best of Lot

If you want to learn Video Editing with Adobe Premiere and After skills, two of the most popular tools for one of the most in-demand and necessary skills for digital marketing, and looking for the best video editing courses then you have come to the right place. Earlier, I have shared the free Adobe Photoshop courses and In this article, I am going to share the best online courses to learn Video editing in 2021 using tools like Adobe Premiere Pro CC and After Effects. These online courses have been taught by expert graphic designers and people who have a strong command of Adobe Premiere Pro and After effects and trusted by thousands of people who wanted to learn Video editing in 2021 and add a useful skill to your Resume.

# How to Print all leaf Nodes of a Binary tree in Java [ Coding Interview Questions]

This is another interesting coding problem that is based on a binary tree and mostly asked beginner programmers. If you have some experience in solving binary tree-based problems then it's rather easy to solve because, like many other binary tree algorithms, you can use recursion to print all leaf nodes of a binary tree in Java. Since the tree is a recursive data structure, you can apply the same algorithm to both the left and right subtree. In order to solve this problem, the first thing you should know is what is a leaf node because if you don't know that then you won't be able to solve the problem. Well, a leaf node is the one whose left and right child nodes are null.

# 5 Free Online Courses to learn Photoshop for Graphic Design in 2021 - Best of Lot

If you want to become a web designer or Graphics designer and want to learn Photoshop and looking for the best online courses to learn Photoshop from scratch on Udemy, Pluralsight, and Coursera then you have come to the right place. In the past, I have shared free web design courses, and In this article, I am going to share 5 free courses from Udemy and Coursera to learn Photoshop online. These Photoshop courses have been created by expert Graphic designers and Photoshop experts and trusted by thousands of developers to learn Photoshop skills and they are absolutely free. You can use them to learn Photoshop skills and start your career as a Graphic designer or Web designer.

# 10 Things about Array Every Java Programmer Should Learn [UPDATED]

Without any doubt, the array is one of the most used data structures in all programming languages, including Java. Pick up any programming language be it functional, object-oriented, imperative, or even scripting languages like Python, Bash, and Perl, you will always find an array. That's why it's important for any programmer to have a good understanding of the array data structure. Like any other data structure, the array also provides a way to organize and store objects, but the way it does makes all the difference. An array is used to store elements in the contiguous memory location and many C, C++ programmers can take advantage of a pointer to work with an array.

# 5 Free Courses to Crack Google Cloud Professional Data Engineer Certification Exam

If you are preparing for Google Cloud Professional Cloud Data Engineer certification or simply known as GCP Data Engineer exam in 2021 and looking for free online Google cloud Engineer courses then you have come to the right place. In the past, I have shared the best courses to learn Google Cloud as well as the best online training courses to pass cloud engineer, cloud developer, and cloud architect certifications, and today, I am going to share free GCP Cloud Data Engineer certification courses for both beginners and experienced cloud professionals.

# Binary tree InOrder traversal in Java using Recursion

The InOrder traversal is one of the three popular ways to traverse a binary tree data structure, the other two being the preOrder and postOrder. During the in-order traversal algorithm, the left subtree is explored first, followed by root, and finally nodes on the right subtree. You start traversal from root then go to the left node, then again go to the left node until you reach a leaf node. At that point in time, you print the value of the node or mark it visited and moves to the right subtree. Continuing the same algorithm until all nodes of the binary tree are visited. The InOrder traversal is also known as the left-node-right or left-root-right traversal or LNR traversal algorithm.

# Top 5 Online Courses to learn Unity Game Engine for Beginners in 2021 - Best of Lot

If you are learning Unity 3D in 2021 and looking for the best online course to learn Unity 3D and become a professional Game developer then you have come to the right place. In the past, I have shared some free courses to learn the C# programming language and Game development basics using Unity 3D, and other popular Game engines available on market like Unreal Engine, Libgdx, and today, I am going to share the best Unity 3D and 2D courses from Udemy, Pluralsight, and Coursera to learn this useful skill.

# 3 ways to Count words in Java String - Google Interview Questions

Today, I am going to share with you Java interview questions from Google, which were asked to one of my readers during the telephonic round. How do you count the number of words in a given String in Java? You can count words in Java String by using the split() method of String. A word is nothing but a non-space character in String, which is separated by one or multiple spaces. By using a regular expression to find spaces and split on them will give you an array of all words in a given String. This was the easy way to solve this problem as shown here, but if you have been asked to write a program to count a number of words in a given String in Java without using any of String utility methods like String.split() or StringTokenizer then it's a little bit challenging for a beginner programmer.

# Top 5 Agile and Scrum Courses for Programmers in 2021 - Best of Lot

If you are a programmer, software developer, team lead, or project manager who wants to learn Agile and Scrum in 2021 and looking for the best Agile courses then you have come to the right place. Earlier, I have shared free Agile courses and books, and today, I am going to share the best Agile and Scrum online courses you can join in 2021 to learn these in-demand skills. The Agile software development approach is a powerful approach that is very popular among the development community. As technology is advancing at a rapid pace, the client expectations are high and the delivery time is less.

# How to implement Radix Sort in Java - Algorithm Example

The Radix sort, like counting sort and bucket sort, is an integer-based algorithm (I mean the values of the input array are assumed to be integers). Hence radix sort is among the fastest sorting algorithms around, in theory. It is also one of the few O(n) or linear time sorting algorithms along with the Bucket and Counting sort. The particular distinction for radix sort is that it creates a bucket for each cipher (i.e. digit); as such, similar to bucket sort, each bucket in radix sort must be a growable list that may admit different keys.

# 5 Free Google Cloud Developer Certification Courses in 2021 - Best of Lot

If you are preparing for Google Cloud Professional Cloud Developer certification and looking for free Google cloud courses to learn online then you have come to the right place. In the past, I have shared the best courses to learn Google Cloud as well as certification courses to pass cloud engineer, data engineer, and cloud architect certifications, and today, I am going to share free Google Cloud Professional Cloud Developer certification exam courses for both beginners and experienced IT  professionals. This is one of the best exams for a Software developer who wants to learn Google Cloud Platform from a developer's point of view.