Review — Is Udemy Still Worth It in 2025?

Hello guys, If you are wondering whether Udemy is a good place to learn Tech skills or not or whether Udemy courses are really worth it? then you have come to the right place. I have been using Udemy since last 7 years and have taken hundreds of courses and still taking to learn in-demand tech skills like AI and LLM Engineering. From my experience, I can say that, as of 2025, Udemy remains one of the world’s largest online learning platforms, hosting a vast library of courses curated by industry professionals. 

Is Coursera Plus Worth It in 2025? A Detailed Review (with 30% Discount)

Hello guys, online learning has completely transformed in the past few years. With advancements in AI, cloud, and data-driven technologies, professionals are now expected to constantly upskill to remain competitive. Traditional degrees often aren’t enough on their own, and that’s where flexible online platforms like Coursera come in. Among Coursera’s offerings, Coursera Plus has become one of the most popular subscription plans for learners who want unlimited access to top-rated courses and professional certificates. But in 2025, with so many online education options available, the question naturally arises: Is Coursera Plus still worth it?

Review — Is Codecademy Courses Worth It in 2025?

Hello guys, When it comes to learning how to code online, Codecademy has been one of the most recognized platforms for over a decade. Since its launch in 2011, it has helped millions of learners around the world get started with programming, web development, data science, and other tech-related fields. What makes Codecademy stand out is its interactive learning environment, where you don’t just watch videos but actually write code in the browser and get instant feedback.

Review – Is Baeldung’s Spring Framework and Spring Boot Courses Worth It in 2025?

Hello guys, Spring has been the backbone of enterprise Java development for years, but as the ecosystem evolves—Spring Boot 3, Reactive APIs, modern security practices—it’s easy to fall behind. If you’re a developer looking to stay cutting-edge, Baeldung’s curated and instructor-led Spring courses are among the most highly recommended. Yet, with pricing higher than general platforms, the question remains: Are they truly worth the investment in 2025?

Is Java Specialists Superpack Course by Heinz Kabutz Worth it in 2025?

Hello guys, if you’ve been a Java developer for a while, you’ve probably hit that point where you feel comfortable with the basics but start asking yourself: “What’s next? How do I go from being just good at Java to truly mastering it?” . That’s exactly where Heinz Kabutz’s Java Specialists Superpack 2025 comes in. And it’s not your average online course—it’s more like a complete university for senior Java developers, condensed into one structured, ever-expanding bundle.

Let’s break it down.

Top 10 Educative.io Courses For Python Developers in 2025 - Best of Lot

Hello guys, if you want to learn Python online and looking for best interactive courses to learn Python and related skills like Django, Flask, NumPy, Pandas etc then you have come to the right place. Earlier, I have shared best Python courses, books, websites, roadmap, and projects and in this article, I am going to share best interactive online courses to learn Python from Educative, one of the best platform for interactive coding and learning. But, Before we get to the 10 best Educative Python courses that will teach you everything you need to know about Python. let me tell you a little bit about what it really is. 

Review - Is Software Engineering at Google Book Worth Reading?

Hello guys, if you have heard about "Software Engineering at Google" book and wondering whether its worth your time and money or not then you have come to the right place. I mentioned about this book on, one of must read books for developers and in this article, I am going to provide you detailed review of this book. While most technical titles teach you how to write code. Software Engineering at Google takes a different path—it's not about syntax or algorithms, but about building software systems that endure or can survive on production. 

Bugfree.ai Review — Is Bugfree.ai Worth It for System Design Interview Prep?

Hello guys, If you’re preparing for system design interviews—especially for FAANG or top-tier tech roles—you’ve likely encountered Bugfree.ai. In the past, I have tried various online platforms to learn System Design like ByteByteGo but one thing I missed is online interactive practice, something like LeetCode where I can solve problems, get it evaluated and also get points to move up the leader board. During my search, I have recently come across this amazing platform and its the platform brands itself as “LeetCode for System Design,” offering a mix of mock interviews, structured question practice, real-time feedback, and more. 

But does it truly deliver value? Let’s break it down.

DesignGurus Review 2025 — Is DesignGurus a Good Place for Coding Interview Preparation?

Hello guys, as tech interviews get tougher, many aspiring engineers look beyond LeetCode and books for structured, pattern-driven prep. If you are one of them and looking for best coding interview resources then you have come to the right place. Earlier, I have shared best coding interview courses and books and now I will explain why DesignGurus.io is a great place to prepare for coding interviews in 2025. If you don't know, DesignGurus.io—the platform behind the now-famous Grokking series of courses. But in 2025, with so many options, is it still worth your time and money?

Let's explore what DesignGurus offers, how it stacks up, and who will benefit most from it.

Top 5 Udemy Courses to learn SnowFlake in 2025 - Best of Lot

As early as a decade ago, setting up a data warehouse meant that you had to literally purchase very expensive hardware appliances and then connect them to your data center. SnowFlake was founded in July 2012. And soon, it was goodbye to all those cumbersome machines and unnecessary expenses. I can see some of you guys wondering: wait, what exactly is SnowFlake? Don't worry. I have got your back. SnowFlake is basically a cloud-native platform that frees you to set up separate data warehouses and data lakes as well as allows you to secure data sharing across your organization. The main motto of SnowFlake is that technology should not come in the way of creativity and imagination.

Exponent Review 2025 – Is Exponent Worth It for Tech Interviews?

Hello guys, Preparing for tech interviews has become a full-time job for many software engineers, product managers, data scientists, and designers. With FAANG-level competition and new AI-driven startups raising the bar, interview prep platforms have become the go-to choice for candidates worldwide. Among them, Exponent has carved a strong niche. But is Exponent worth it in 2025? Let’s dive into what the platform offers, its strengths, weaknesses, and how it stacks up against alternatives.

Why Should You Take Udacity Courses? Is Udacity worth it?

Online learning is probably the most brilliant idea on the internet. People now can learn anything there and get valuable skills from home for a small amount of money and sometimes for free without spending that much money on college, and sometimes you don’t get real-world experience for that job, but things are changing now with likes of Google and Meta providing online courses which not only teach you in-demand skills but also give some exposure to practical work.  Many online platforms are competing to get more students enrolled in their programs and one of the best is called Udacity.

Review - Is Modern HTML & CSS From The Beginning Course by Brad Traversy on Udemy Worth it?

Hello guys, if you want to learn HTML and CSS from scratch and in depth and looking for best resources like online courses, books, tutorials, and websites then you have come to the right place. In the past, I have shared both best paid HTML courses as well as best free HTML and CSS courses and in this article, we are going to review one of the best Udemy course to learn HTML and CSS, The Modern HTML & CSS From the Beginning by none other than Brad Traversy.

Udemy Course Review - Is REST APIs with Flask and Python in 2025 Course by Teclado Worth it?

Hello guys, if you are looking for an online course to learn how to use Flask and Python to create REST API then you have come to the right place. Earlier, I have shared both best Python courses and best Flask courses and in this article, we will review one of Udemy's popular REST APIs with Flask and Python  in 2025 course by Jose Salvatierra and Teclado. Building web applications can be a challenging task when learning them from scratch but what makes them harder is that you get confused about which programming language or framework to choose for building your project. .

3 Ways to Learn React.js for web development in 2025 - Best of Lot

Hello guys, if you want to learn React.js in 2025 and looking for best way to learn React.js in quick time then you have come to the right place. Earlier, I have shared React.js Developer RoadMap as well best React courses, books, websites, and React projects for you and in this article, I am going to share what is the best way to learn React.js in quick time and also in depth. But, before that, let's find out what is React.js and why every web developer should learn React.js in 2025. According to the Stack Overflow developer’s survey, React.js surpassed jQuery to become the most popular web framework in the world. 

Top 5 Courses to Learn Apache Solr in 2025 - Best of Lot

Hello guys, if you want to learn Solr and looking for best resources like online courses then you have come to the right place. Solr is a search platform that is open-source and may be used to create search apps. It was constructed on top of Lucene (full text search engine). Solr is an enterprise-ready, fast, and scalable search engine. Solr-based apps are smart and provide excellent performance. Hadoop and Solr may work together. Solr assists us in discovering the essential information from such a vast source since Hadoop manages a large volume of data. Solr may be used for more than just searching. It can also be used to store data. 

Review - Is Coursera's Python 3 Programming Specialization Worth it in 2025?

Hello guys, In the ever-evolving realm of programming languages, Python stands as a versatile and in-demand tool, powering applications across diverse domains, from web development to data science and artificial intelligence. As aspiring programmers and seasoned developers alike seek effective ways to master Python, Coursera's Python 3 Programming Specialization emerges as a potential beacon, promising a structured and comprehensive journey through the intricacies of this powerful language. While Coursera has many great Python courses and certifications like Google's Python for IT Automation and the world famous Python for Everybody certification, this Python 3 specialization from University of Michigan is certainly worth it for its comprehensive coverage, engaging explanation and well structured content.

Top 5 Books to Learn Blockchain for Beginners in 2025 - Best of Lot

Hello guys, if you are looking for best books to learn Blockchain technology in 2025 then you have come to the right place. Earlier, I have shared best Blockchain courses, certifications, and best websites to learn Blockchain and today, I will share best books to learn Blockchain. While Online courses are easier way to learn a new technology like Blockchain they cannot replace books which is more accurate and comprehensive resource to learn Blochian in depth. I generally start with a course and then moved to reading books to learn any new technology in depth and Blockchain in no different. 

Top 5 Machine Learning Books for Beginners in 2025 - Best of Lot

Hello guys, if you want to learn Machine learning in 2025 and looking for best resources like Machine learning best books, or machine learning best courses then you have come to the right place. Earlier, I have shared machine learning best courses and best python books for Machine learning and in this article, I am going to share best books to learn Machine Learning for Beginners in 2025. Machine learning and artificial intelligence are booming fields in today's world. This industry has made humanity life’s easier by automating tasks or improving things that we always need such as translation, fraud detection in money transactions, stock prediction before you make an investment and so much stuff that you couldn’t imaging.

Why Join ByteByteGo to Learn Coding Interview Patterns in 2025?

Hello guys, Preparing for coding interviews in 2025 is more challenging than ever. With companies expecting candidates to not only solve problems quickly but also explain trade-offs, patterns, and scalability, having the right preparation resource is crucial. That’s where ByteByteGo shines. If you’ve been following interview trends, you’ll notice that top tech companies now focus less on memorization and more on how well you understand patterns of problem-solving. 

Instead of just practicing 500 random LeetCode problems, engineers are expected to recognize underlying patterns and apply them to new situations. 

ByteByteGo has designed its platform around this very idea—master the patterns, not the problems.

Top 7 Books to Learn Big Data, Hadoop and Spark in 2025 - Best of Lot

Hello guys, if you want to learn Big Data in 2025 and looking for best resources like books, online courses, tutorials, projects, and interview questions then you have come to the right place. Earlier, I have shared best Big Data courses and in this article, I am going to share best books to learn Big Data in depth. But, before we get to the 7 best books that you can read to learn everything you need to know about big data, let me tell you what it really is. Big data basically refers to a collection of data that is really huge in size and is growing exponentially over time. It is really large and complex which means that traditional data management tools cannot store and process it efficiently. You can see big data as data that is really huge in size.

Top 5 Books To Learn Cyber Security and Information Security in 2025 - Best of Lot

Hello guys, if you want to learn Cyber Security in 2025 and looking for best resources like best books and online courses then you have come to the right place. Earlier, I have shared best Cyber Security Courses, Tools, and Skills and today, I am going to share best Cyber Security books for both beginners and experienced IT professionals. You can read these books to learn important Cyber Security concepts and tools. Nowadays, cyber security is fun and increases awareness since the bad guys are attacking users' computers and other devices and other companies for stealing sensitive information and money. If you want to protect yourself from these attacks, I highly suggest taking one of these books t help you understand cyber security.

Review - Is Effective Java, 3rd Edition Still Worth it in the era of Java 24?

Hello guys, I have an interesting news to share with you today. After a long wait of almost 10 years, the Effective Java 3rd edition is finally coming this year, hopefully, December 2017. The Effective Java 2nd Edition was released in May 2008 and updated for Java SE 6, but it been, good 10 years now and there is a lot of interest from Java developers around the world for Effective Java 3rd edition after Java SE 8 release and I am very happy to inform you guys that, finally, all our wishes are granted and Effective Java 3rd edition is set to arrive this year. It will not only cover Java 9 release but also all the changes from Java 7 and Java 8.

Review - Is Fintech Certification CFTE on 101 Blockchain worth it in 2025?

The domain of fintech or financial technology has been growing at a rapid pace, with new innovations making a mark. At this point in time, the demand for a fintech certification course is increasing consistently as more professionals want to pursue their careers in fintech. Market research reports have indicated that the global fintech market could achieve a capitalization of almost $174 billion in 2025. The fintech industry has registered promising growth in terms of investment, adoption rates and a number of fintech startups. As of now, there are more than 35,000 fintech startups worldwide. On top of it, the total value of investment in fintech amounted to almost $164 billion dollars in 2022.

Top 7 Books to Learn Golang or Go in 2025 - Best o fLot

Hello guys, if you want to learn Golang in 2025, one of the trendy and rising programming language for backend development and looking for resources like online courses and books, and tutorials then you have come to the right place. Earlier, I have shared best free Golang courses, and best paid Golang courses and in this article, I am going to share best books you can read to learn Golang in depth. But, before we get to the 7 best books that will teach you everything you need to know about the Golang language, let me tell you what it really is. 

Top 7 Books to Learn Kubernetes in Depth - Best of Lot

Hello guys, if you want to learn Kubernetes and looking for resources like books, online courses, tutorials and online platforms where you can learn and practice Kubernetes then you have come to the right place. Earlier, I have shared best free Kubernetes courses as well as best Kubernetes paid courses and in this article, I am going to share best books you can read to learn Kubernetes in depth. But, before we get to the 7 best books that you can read to learn everything you need to know about Kubernetes, let me tell you what it really is. Kubernetes is basically an open-source container orchestration platform that was originally designed by Google. The main goal of Kubernetes is to automate the deployment, scaling, and management of containerized applications.

Top 20 Linux Interview Questions with Answers for 1 to 3 Years Experienced Developers

Hello guys, if you are preparing for Developer and DevOps interview and looking for Linux questions for interviews then you have come to the right place. Earlier, I have shared popular UNIX Interview questions and DevOps Interview Questions and in this article, I am going to share 20 common Linux questions from interviews with Answers. These questions covers essential Linux commands like Linux file system, permission model, Linux commands, shell and kernels etc. If you have worked in Linux then you can easily answer these questions but if you have forgot them then you can always join these best Linux courses to learn and revise key Linux concepts before interviews. 

Top 10 Coursera Courses to Learn Artificial Intelligence in 2025

Hello guys, Artificial Intelligence (AI) is no longer just a futuristic buzzword — it's an essential skill in 2025 across industries like Coding, Testing, healthcare, finance, education, and software engineering. Whether you’re a developer, business leader, student, or tech-curious professional, understanding how AI works — and how to use it responsibly — is more critical than ever. Coding tools like GitHub Copilot and ChatGPT and Claude all are getting better and better and as a Software Developer if you are not using it then you are really missing out. 

10 Example of netstat networking command in UNIX and Linux

The netstat command is one of the most essential and useful networking command for Linux users. It is a general, all purpose network information tool which can be used to find out information about current network connections, multicast group membership, routing tables, network interface statistics and many other low-level details of the host's current network configuration. The good knowledge of netstat command is not only important from the troubleshooting perspective but also from security perspective. It gives useful security related information e.g. what network ports are currently "open" on your system and the list of current network connections and their states. 

Is CodeGym Good Place to Learn Java? Is CodeGym Premium Worth it?

>Hello guys, if you are learning Java or want to learn Java but not sure if CodeGym is the right place for you or not then you have come to the right place. Earlier, I have shared best places to learn Java coding for FREE and in this article, I will review CodeGym, one of the interactive platform to learn Java. But, Before we see whether CodeGym is worth it for learning and mastering Java, let me tell you a little bit about what CodeGy really is.   CodeGym is an excellent and innovative alternative to traditional learning platforms like Udemy and Coursera. 

10 Best Python Courses and Certification on Coursera in 2025

Hello guys, Python continues to dominate the programming world in 2025 — and for good reason. From web development and data science to machine learning and automation, Python is the go-to language across industries. Whether you're a complete beginner looking to write your first line of code or a seasoned developer expanding into AI, Python remains a powerful skill with high job market demand and versatility.

Top 5 Udemy Courses to Learn Test-Driven Development in 2025 - Best of Lot

Before we get to the 5 best courses that will teach you everything you need to know about test-driven development, let me tell you a little bit more about what test-driven development really is. Test Driven Development is basically a particular approach to software development. In Test Driven Development, test cases are taken and developed to specify and validate what the code will do. Test cases are created for each functionality. If the test fails, then the code is written again in order to pass the test. This makes the code simple and free of bugs.

Top 25 Vue.js Interview Questions and Answers for Web Developers

Hello guys, if you are preparing for Vue.js interviews and looking for some frequently asked Vue.js questions from interviews then you have come to the correct place. Earlier, I have shared React.js Interview questions and JavaScript questions and in this article, I am going to share common Vue.js Interview questions for 1 to 2 years experienced web developers. With the success of libraries like React.js, developers around the globe are leaning more towards such flexible technologies. Though full-fledged frameworks like Angular are also popular and widely used, developers want flexibility.

Why Join ByteByteGo to Learn System Design in 2025?

If you’re preparing for FAANG or top-tier tech interviews in 2025, system design is one of the toughest hurdles you’ll face. It’s no longer enough to be great at data structures and algorithms — recruiters and hiring managers want to know if you can design scalable, fault-tolerant, production-level systems. That’s where ByteByteGo truly shines. Created by Alex Xu, the author of the bestselling System Design Interview series, ByteByteGo has quickly become one of the most trusted resources for mastering modern system design. It’s designed for both interview prep and real-world software architecture learning — whether you’re a junior developer looking to step up, or a senior engineer preparing for staff+ roles.

Is the Google Data Analytics Professional Certificate on Coursera Worth It in 2025? [Complete Review]

If you're planning a career pivot or just entering the world of data, you’ve likely come across the Google Data Analytics Professional Certificate on Coursera. With nearly 3 million learners enrolled, a stellar 4.8 rating from over 158,000 reviews, and a career-ready curriculum designed by Google, it’s one of the most popular data certifications available today. But the big question is: Is it still worth it in 2025?  Let’s break it down, from course content to career outcomes, skill development, and cost-efficiency,  with a practical lens from the perspective of an experienced Data Analyst.

10 Best System Design Books for Senior Software Engineer Interviews in 2025 (With Courses)

Hello guys, if you are a senior software engineering preparing for tech interviews in 2025 then you must have thought about System design interview, one of the toughest part of tech interviews. Not many people can crack it because of its open ended and vast nature, in fact, I have failed many System design interviews in the past before I cracked one.

Review - Is the Microsoft AI & ML Engineering Professional Certificate Worth It?

Hello there! If you’re looking to build a serious career in AI and ML Engineering in 2025 without burning a hole in your pocket, then you’ve landed at the right place. While many of my friends are spending thousands in AI Bootcamp, I am quietly learning on my own using online courses and certifications.  In this article, I will share one such resource, the Microsoft AI & ML Engineering Professional Certificate—available on Coursera—for those who wish to launch or advance their AI/ML careers in 2025. 

Is Introduction to Generative AI Learning Path Specialization by Google Cloud on Coursera Worth It?

Hello guys, the world of Artificial Intelligence is evolving fast — and if you're aiming to ride the wave of innovation, getting a strong foundation in Generative AI is no longer optional. Whether you're a software engineer, product manager, data scientist, or just an AI enthusiast, Google Cloud's “Introduction to Generative AI Learning Path” on Coursera offers a structured, high-quality way to start or deepen your journey. 

But the question is: Is it worth your time and investment in 2025?

Let’s break it down.

Coursera Plus Discount SALE 2025: 40% Off Now—Just $240 Instead of $360 for 12 Months!

Hello guys, If you're dreaming of advancing your career this summer—especially in the hot fields of AI, LLM Engineering, Agentic AI, Machine Learning, Deep Learning, and more—there’s no better time than now to dive in. For a limited period, Coursera Plus is available at 40% off: just $240 for 12 months (regular price $399). This offer ends July 21, 2025, so time is of the essence.

Here’s why this deal is worth your attention—and how Coursera Plus can help you build job-ready skills that stand out.

Top 10 SQL Queries from Technical Interviews to Learn Window Functions like ROW_NUMBER

Hello guys, If you're preparing for SQL interviews or working on real-world reporting tasks, mastering window functions is no longer optional. They are one of the most powerful tools in SQL which allows you to perform calculations across rows related to the current row without collapsing your result set like GROUP BY does. Window functions like ROW_NUMBER(), RANK(), LEAD(), LAG(), and SUM() OVER help you write cleaner, faster, and more expressive queries—ideal for performance tuning and analytical processing.

Let’s dive into the Top 10 SQL window function queries that you must know.

What is PriorityQueue or priority queue in Java with Example - Tutorial

PriorityQueue is an unbounded Queue implementation in Java, which is based on a priority heap. PriorityQueue allows you to keep elements in a particular order, according to their natural order or custom order defined by the Comparator interface in Java. Head of priority queue data structure will always contain the least element with respect to specified ordering. For example, in this post, we will create a PriorityQueue of Items, which are ordered based upon their price, this will allow us to process Items, starting from the lowest price. A priority queue is also very useful in implementing the Dijkstra algorithm in Java. You can use to PriorityQueue to keep unsettled nodes for processing.

What is EnumMap in Java – Example Tutorial

What is EnumMap in Java

EnumMap in Java is added on JDK  5 release along with other important features like  Autoboxing, varargs, and Generics. EnumMap is a specialized Map implementation designed and optimized for using Java Enum as key. Since enum can represent a type (like class or interface)  in Java and it can also override equals() and hashCode(), It can be used inside HashMap or any other collection but using  EnumMap brings implementation-specific benefits which are done for enum keys, In short EnumMap is optimized Map implementation exclusively for enum keys. As per Javadoc Enum is implemented using Arrays and common operations result in constant time.

How to use CopyOnWriteArraySet in Java with Example

CopyOnWriteArraySet is little brother of CopyOnWriteArrayList class. These are special purpose collection classes which was added on JDK 1.5, along with their most popular cousin ConcurrentHashMap. They are part of concurrent collection framework and reside in java.util.concurrent package. CopyOnWriteArraySet is best suited as a read-only collection whose size is small enough to copy if some mutative operation happens, for example, you can use CopyOnWriteArraySet to store objects at the start-up of the application and let multiple application thread access them during application life time. If an new condition or object comes up during that time, it can also be added into this Set, with incurring cost of creating a new array.

2 Example to Merge or Join Multiple List in Java - Tutorial

Sometimes, we need to merge multiple lists into one before performing any operation, say Iteration or transformation. It's quite common to merge two lists, or combine them into a bigger list and there are multiple ways to do it. In this article, we will take a look at two simple way to join two lists in Java, you can further extend that idea to join any number of List or it's implementation e.g. ArrayList or LinkedList in Java. One way to merge multiple lists is by using addAll() method of java.util.Collection class, which allows you to add the content of one List into another List. By using the addAll() method you can add contents from as many List as you want, it's the best way to combine multiple List.

How to Create Read Only List, Map and Set in Java? UnModifiable Collection Example

Read-only List, Map and Set in Java

A read-only List means a List where you can not perform modification operations like add, remove or set. You can only read from the List by using the get method or by using the Iterator of List, This kind of List is good for a certain requirement where parameters are final and can not be changed. In Java, you can use Collections.unModifiableList() method to create read-only List, Collections.unmodifiableSet() for creating read-only Set like read-only HashSet and similarly creating a read-only Map in Java, as shown in below example. Any modification in the read-only List will result in java.lang.UnSupportedOperationException in Java.  

Top 6 AI and Prompt Engineering Books for Software Engineers in 2025

Hello guys, AI and Large Language Models (LLMs) are transforming the software engineering landscape. While many developers use tools like ChatGPT or GitHub Copilot, understanding the engineering principles behind them is essential to stay relevant in 2025 and beyond.  While there are many resources to learn about AI Engineering, Prompt Engineering and LLM Engineering, and I have also shared online courses and roadmap, books offer structured and in-depth learning that videos and blogs often lack. They are often created by true experts and authorities who have done a lot of research in that area and that's why I always include book in my learning process.

How to use ConcurrentHashMap in Java - Example Tutorial and Working

ConcurrentHashMap in Java is introduced as an alternative of Hashtable in Java 1.5 as part of the Java concurrency package. Prior to Java 1.5 if you need a Map implementation, which can be safely used in a concurrent and multi-threaded Java program, then, you only have Hashtable or synchronized Map because HashMap is not thread-safe. With ConcurrentHashMap, now you have a better choice; because not only it can be safely used in the concurrent multi-threaded environment but also provides better performance over Hashtable and synchronizedMap.

How to use EnumSet in Java with Example

EnumSet is one of the specialized implementations of the Set interface for an enumeration type, introduced in Java 1.5 along with the enumeration type itself. Programmer often stores Enum into common collection classes e.g. HashSet or ArrayList, mostly because they are unaware of this little gem. Even I wasn't aware of this class a few years ago until I come across one of the finest books for Java programmers, Effective Java. It has an Item on EnumSet, which highlights some typical use-cases for this collection class instead of using int variable and bitwise operator. Since Enum constants are unique and have pre-defined lengths, as you can not define a new enum constant at runtime; it allows Java API designers to highly optimize EnumSet.

What is difference between Enumeration and Iterator in Java? Answer

Though both Iterator and Enumeration allows you to traverse over elements of Collections in Java, there is some significant difference between them e.g. Iterator also allows you to remove elements from the collection during traversal but Enumeration doesn't allow that, it doesn't get remove() method. Enumeration is also a legacy class and not all Collection supports it e.g. Vector supports Enumeration but ArrayList doesn't. On the other hand, Iterator is the standard class for iteration and traversal. By the way,  what is the difference between Enumeration and Iterator in Java? 

Top 11 Java ConcurrentHashMap Interview Questions with Answers [UPDATED]

The ConcurrentHashMap class part of concurrent collections package added on JDK 1.5 which contains utility classes like BlockingQueue, CopyOnWriteArrayList, CopyOnWriteArraySet etc. It is a replacement of synchronized hash-based map implementations e.g. Hashtable and synchronized HashMap. It implements Map and ConcurrentMap (a sub-interface of Map) interface which allows you to store key-value pairs. The class is similar to HashMap or Hashtable but it's more scalable and the right fit for concurrent Java application. Unlike Hashtable which achieves its thread-safety by compromising the scalability, ConcurrentHashMap uses advanced techniques e.g. dividing the map into segments to remain thread-safe and scalable at the same time.

How HashMap works in Java?

Hello guys, if you are looking for an answer of popular Java interview question, how HashMap works in Java? or How HashMap works internally in Java then you have come to the right place. In this article, I will not just answer those question but also many related questions like How get() and put() method works in Java? what role equals() and hashcode() play in HashMap, How HashMap resize itself, and why key object of HashMap should be Immutable in Java. Let's start with the basics first. HashMap in Java works on hashing principles. It is a data structure that allows us to store object and retrieve it in constant time O(1) provided we know the key. Also this is one of my most popular article with more than 6 million views and I have now updated it to include latest information like how HashMap now uses a balanced tree instead of linked list for storing collision objects and new diagrams on HashMap working which provide visual explanations. 

Difference between fail-safe vs fail-fast Iterator in Java? Example

The difference between fail-safe and fail-fast Iterator is becoming favorite core java interview questions day by day, the reason it touches concurrency a bit, and the interviewee can go deep on it to ask how fail-safe or fail-fast behavior is implemented. In this article, we will see what are fail-safe and fail-fast iterators in java and the differences between fail-fast and fail-safe iterators. The concept of the fail-safe iterator is relatively new in Java and was first introduced with Concurrent Collections in Java 5 like ConcurrentHashMap and CopyOnWriteArrayList.

Difference between List and Set in Java Collection? Example

What is the difference between List and Set in Java is a very popular Java collection interview question and an important fundamental concept to remember while using the Collections class in Java. Both List and Set are two of the most important Collection classes Java Program use along with various Map implementations. The basic feature of List and Set are abstracted in the List and Set interface in Java and then various implementations of List and Set adds specific features on top of that e.g. ArrayList in Java is a List implementation backed by Array while LinkedList is another List implementation that works like linked list data-structure.

Difference between ArrayList and Vector in Java

ArrayList and Vector are two of the most used classes on the java collection package and the difference between Vector and ArrayList is one of the most frequently asked java interview questions on first-round or phone interviews. Though it’s quite a simple question in my opinion but knowledge of when to use Vector over ArrayList or does matter if you are working on a project. In this article, we will some point-based differences between Vector and ArrayList in Java and trying to understand the concept behind those differences. 

What is difference between HashMap and Hashtable in Java?

HashMap vs Hashtable in Java
Though both Hashtable and HashMap are data-structure based upon hashing and implementation of Map interface, the main difference between them is that HashMap is not thread-safe but Hashtable is thread-safe. This means you cannot use HashMap in a multi-threaded Java application without external synchronization. Another difference is HashMap allows one null key and null values but Hashtable doesn't allow null key or values. Also, the thread-safety of the hash table is achieved using internal synchronization, which makes it slower than HashMap.

Difference between LinkedList and ArrayList in Java

LinkedList and ArrayList both implement List Interface but how they work internally is where the differences lie. The main difference between ArrayList and LinkedList is that ArrayList is implemented using a resizable array while LinkedList is implemented using doubly LinkedList. ArrayList is more popular among Java programmers than LinkedList as there are few scenarios on which LinkedList is a suitable collection than ArrayList. In this article, we will see some differences between LinkedList and ArrayList and try to find out when and where to use LinkedList over ArrayList.

Difference between TreeSet, LinkedHashSet and HashSet in Java with Example

TreeSet, LinkedHashSet, and HashSet all are implementation of the Set interface and by virtue of that, they follow the contract of Set interface i.e. they do not allow duplicate elements. Despite being from the same type of hierarchy,  there are a lot of differences between them; which is important to understand, so that you can choose the most appropriate Set implementation based upon your requirement. By the way difference between TreeSet and HashSet or LinkedHashSet is also one of the popular Java Collection interview questions, not as popular as Hashtable vs HashMap or ArrayList vs Vector but still appears in various Java interviews.

Difference between PriorityQueue and TreeSet in Java? Example

The PriorityQueue and TreeSet collection classes have a lot of similarities e.g. both provide O(log(N)) time complexity for adding, removing, and searching elements, both are non-synchronized and you can get elements from both PriorityQueue and TreeSet in sorted order, but there is a fundamental difference between them, TreeSet is a Set and doesn't allow a duplicate element, while PriorityQueue is a queue and doesn't have such restriction. It can contain multiple elements with equal values and in that case head of the queue will be arbitrarily chosen from them.

Difference between Synchronized and Concurrent Collections in Java? Answer

Synchronized vs Concurrent Collections
Though both Synchronized and Concurrent Collection classes provide thread-safety, the differences between them come in performance, scalability, and how they achieve thread-safety. Synchronized collections like synchronized HashMap, Hashtable, HashSet, Vector, and synchronized ArrayList are much slower than their concurrent counterparts like ConcurrentHashMap, CopyOnWriteArrayList, and CopyOnWriteHashSet. The main reason for this slowness is locking; synchronized collections lock the whole collection e.g. whole Map or List while concurrent collection never locks the whole Map or List.

How to choose the Right Collection Class in Java? List, Set, Map, and Queue Example

The Java collection framework offers implementation of different data structure like an array, list, set, map, queue, tree, etc and the choice really depends upon the situation and properties of the different data structure. For example, if your requirement is fast search with index then you can use ArrayList and if you want to store key-value pairs then you would consider using hash table data structure and there are a couple of implementation of hash table data structure in Java, like HashMap, Hashtable, LinkedHashMap, TreeMap, and ConcurrentHashMap. Now, which one will you choose? If you don't know or confused don't worry, I will give you a set of rules and use cases which will help you choose the right Collection type in Java depending upon scenario. 

Difference between HashMap, LinkedHashMap and TreeMap in Java with Example

Hello guys, if you are wondering what is difference between HashMap, TreeMap, and LinkedHashMap in Java and when to use them then you are at the right place. In past, I have shared frequently asked HashMap Interview questions and ConcurrentHashMAp Interview questions and today, I Will answer this question in detail. The java.util.Map is one of the most important interfaces from the Java Collection Framework.  It provides hash table data structure functionality by its implementations like HashMap, Hashtable, LinkedHashMap, and a little bit of sorting with the TreeMap. So if you are looking to store key-value pairs in the Java program,  you have a wide range of choices available depending upon your requirement. The main difference between LinkedHashMap, TreeMap, and HashMap comes in their internal implementation and specific features, which a Java programmer should know to use them effectively. 

How to get Key From Value in Hashtable, HashMap in Java? Example

It's not easy to get key from the value in Hashtable or HashMap, as compared to getting value from key because HashMap or Hashtable doesn't enforce one to one mapping between key and value inside Map in Java. in fact, Map allows the same value to be mapped to multiple keys inside HashMap, Hashtable, or any other Map implementation. What you have in your kitty is Hashtable.containsValue(String value) or Hashtable.containsKey(String key) to check whether key or value exists in HashMap or not, but sometimes we want to retrieve a value from Map corresponding to any key and there is no API method to do in Map.

Difference between HashMap and IdentityHashMap in Java? Example

Hello guys, if you are wondering what is differnece between an HashMap and IdentiyHashMap in Java then you are at right place. IdentityHashMap in Java was added in Java 1.4 but still, it's one of those lesser-known classes in Java. The main difference between IdentityHashMap and HashMap in Java is that IdentityHashMap is a special implementation of Map interface which doesn't use equals() and hashCode() method for comparing objects unlike other implementations of Map e.g. HashMap. Instead, IdentityHashMap uses the equality operator "=="  to compare keys and values in Java which makes it faster compared to HashMap and suitable where you need reference equality check and instead of logical equality.

What is difference between ArrayList and ArrayList<?> in Java?- Raw Type vs Wildcard Example Tutorial

One of my readers asked me about the difference between ArrayList vs ArrayList< in Java?>, which was actually asked to him in a recent Java development interview. The key difference between them is that ArrayList is not using Generics while ArrayList is a generic ArrayList but they look very similar. If a method accepts ArrayList or ArrayList<?> as a parameter then it can accept any type of ArrayList like ArrayList of String, Integer, Date, or Object, but if you look closely you will find that one is raw type while the other is using an unbounded wildcard. What difference that could make? Well, that makes a significant difference because ArrayList with raw type is not type-safe but ArrayList<?> with the unbounded wildcard is type-safe.

How to Filter Stream and Collections in Java 8? Example Tutorial

Java 8 provides excellent features to support the filtering of elements in Java Collections. Prior to Java 8, the only better way to filter elements is by using a foreach loop or iterating over Collection using the Iterator and selecting the required object, leaving out rest. Though that approach work, it was very difficult to run them in parallel and take advantage of multiple CPUs available in modern-day servers. Java 8 provides Streams, which not only makes it easy to run any operation parallel but also supports lazy loading and lazy evaluation, which means as soon as the filtering condition is satisfied, it stooped doing work, doesn't matter how many objects the collection contains.

Top 25 Java Collection Framework Interview Questions Answers for Freshers and Experienced Programmers

Interview questions from the Collection package or framework are most common in any Core Java Interview yet a tricky one. Together Collection and multithreading make any Java interview tough to crack and having a good understanding of Collection and threads will help you to excel in Java interviews. I thought about writing interview questions on the Java collection framework and important classes like ArrayList, HashMap, Hashtable, and newly added concurrent collections e.g. ConcurrentHashMap when I first wrote 10 multi-threading Interview questions but somehow this article got delayed. Though I have shared several questions individually in between.

How to Convert Collection to String in Java - Spring Framework Example

How to convert Collection to String in Java

Many times we need to convert any Collection like Set or List into String like comma-separated or any other delimiter delimited String. Though this is quite a trivial job for a Java programmer as you just need to Iterate through the loop and create a big String where individual String are separated by a delimiter, you still need to handle cases like the last element should not have a delimiter or at a bare minimum, you need to test that code.

How does Java HashMap or LinkedHahsMap handles collisions?

Prior to Java 8, HashMap and all other hash table based Map implementation classes in Java handle collision by chaining, i.e. they use linked list to store map entries which ended in the same bucket due to a collision. If a key end up in the same bucket location where entry is already stored then this entry is just added at the head of the linked list there. In the worst case this degrades the performance of the get() method of HashMap to O(n) from O(1). In order to address this issue in the case of frequent HashMap collisions, Java8 has started using a balanced tree instead of a linked list for storing collided entries. This also means that in the worst case you will get a performance boost from O(n) to O(log n).

Difference between HashMap and HashSet in Java

HashMap vs HashSet is the most frequently asked question during any core java interview and the interview is not said completed until they will not cover the Collection Framework and multi-threading interview and collections are uncompleted without Covering Hash Set and HashMap.

Both HashMap and HashSet are part of the collection framework which allows us to work with a collection of objects. Collection Framework has its own interfaces and implementation classes. Basically, a collection is divided into Set Interface, List, and Queue Interfaces.

Difference between EnumMap and HashMap in Java? Example

HashMap vs EnumMap in Java

What is the difference between EnumMap and HashMap in Java is the latest Java collection interview question which has been asked to a couple of my friends? This is one of the tricky Java questions, especially if you are not very much familiar with EnumMap in Java, which is not uncommon, given you can use it with only Enum keys. The main difference between EnumMap and HashMap is that EnumMap is a specialized Map implementation exclusively for Enum as key. Using Enum as a key allows doing some implementation level optimization for high performance which is generally not possible with other objects as key.

Difference between ConcurrentHashMap, Hashtable and Synchronized Map in Java

ConcurrentHashMap vs Hashtable vs Synchronized Map
Though all three collection classes are thread-safe and can be used in multi-threaded, concurrent Java application, there is a significant difference between them, which arise from the fact that how they achieve their thread-safety. Hashtable is a legacy class from JDK 1.1 itself, which uses synchronized methods to achieve thread safety. All methods of Hashtable are synchronized which makes them quite slow due to contention if a number of thread increases. Synchronized Map is also not very different than Hashtable and provides similar performance in concurrent Java programs. The only difference between Hashtable and Synchronized Map is that later is not a legacy and you can wrap any Map to create it's synchronized version by using Collections.synchronizedMap() method.

How to Iterate through ConcurrentHashMap and print all keys and values in Java? Example

Suppose you have a ConcurrentHashMap of String and Integer and you want to print all keys and values, how do you do that? This is a common, day-to-day programming task for Java programmers and there are many ways to do it. The Map interface provides several view methods e.g. keySet(), values(), and entrySet() to retrieve all keys, values, and all key and value pairs as entries. You can use respective methods to print all keys, all values, or all key values pairs. For printing, you also have multiple choices like you can either use enhanced for loop or Iterator, though later also provide you the facility to remove key-value pairs while printing if needed.

Enhanced For Loop Example and Puzzle in Java

From Java 5 onwards, we have a for-each loop for iterating over collection and array in Java. For each loop allows you to traverse over collection without keeping track of index like traditional for loop, or calling hasNext() method in while loop using Iterator or ListIterator. For-each loop indeed simplified iteration over any Collection or array in Java, but not every Java programmer is aware of some useful details of the for-each loop, which we will see in this tutorial. Unlike other popular items from Java 5 release alias Generics, Autoboxing, and variable arguments, Java developers tend to use for-each loop more often than any other feature, but when asked about how does advanced foreach loop works or what is a basic requirement of using a Collection in the for-each loop, not everyone can answer.

JUnit4 Annotations : Test Examples and Tutorial

JUnit4 Annotations are a single big change from JUnit 3 to JUnit 4 which is introduced in Java 5. With annotations creating and running a JUnit test becomes easier and more readable, but you can only take full advantage of JUnit4 if you know the correct meaning of annotations used on this version and how to use them while writing tests. In this

Junit tutorial we will not only understand the meaning of those annotations but also we will see examples of JUnit4 annotations. By the way, this is my first post in unit testing but if you are new here than you may like post 10 tips to write better code comments and 10 Object-oriented design principles for Programmer as well.

JUnit Testing Tips - Constructor is Called Before Executing Test Methods? Example

Even though almost all Java programmers either use JUnit or TestNG for their unit testing need along with some mock object generation libraries e.g. Mockito, but not everyone spends time and effort to learn subtle details of these testing libraries, at least not in proportion to any popular framework like Spring or Hibernate. In this blog post, I am sharing one of such detail, which has puzzled me a couple of years ago. At that time, though I had been using JUnit for a significant time, I wasn't aware that code written inside the constructor of the Test class is executed before each test method.

How to Fix Exception in thread "main" java.lang.NoClassDefFoundError: Running Java from Command line

The "Exception in thread "main" java.lang.NoClassDefFoundError: helloworldapp/HelloWorldApp" error comes when you are trying to run the HelloWorldApp Java program from the command line but either .class file is not there or Java is not able to find the class file due to incorrect classpath settings. The name of the class could be different in each case, it depends upon which class you are passing to java command for running from the command prompt. Another interesting thing to remember is that this error only comes in Java version less than or equal to Java 6 like Java 1.5 or Java 1.4, if you are running in JDK 7 or Java 8 instead of this you will see "Error: could not able to find or load class HelloWorldApp". Technically, both errors come due to some reason and their solution is also exactly the same.

How to fix java.io.NotSerializableException: org.apache.log4j.Logger Error in Java? Example

java.io.NotSerializableException: org.apache.log4j.Logger error says that an instance of org.apache.lo4j.Logger is not Serializable. This error comes when we use log4j for logging in Java and create Logger in a Serializable class e.g. any domain class or POJO which we want to store in HttpSession or want to serialize it. As we know from 10 Java Serialization interview question that, if you have a non serializable class as member in a Serializable class, it will throw java.io.NotSerializableException Exception.

Binary Search vs Contains Performance in Java List - Example

There are two ways to search an element in a List class, by using contains() method or by using Collections.binarySearch() method. There are two versions of binarySearch() method, one which takes a List and Comparator and other which takes a List and Comparable. This method searches the specified list for the specified object using the binary search algorithm. The list must be sorted into ascending order according to the natural ordering of its elements (as by the sort(List) method) prior to making this call. If List is not sorted, then results are undefined. If the List contains multiple elements equal to the specified object, there is no guarantee which one will be returned. This method runs in log(n) time for a "random access" list (which provides near-constant-time positional access).

How to Fix Eclipse No Java Virtual Machine was found Windows JRE JDK 64 32 bit Error? Example

One of my readers was installing Eclipse in his Windows 7 x86 machine and emailed me about this error "A java Runtime Environment (JRE) or Java Development kit (JDK) must be available in order to run Eclipse. No Java virtual machine was found". Before getting into details and trying to find root cause and solution of Eclipse Java Virtual Machine not found error, let's see some background about Eclipse. Eclipse is a popular Java IDE, which assists on coding, debugging and running Java program, but the key point is, Eclipse itself need Java to launch and run.

Private in Java: Why should you always keep fields and methods private? Example

Making members private in Java is one of best coding practice. Private members (both fields and methods) are only accessible inside the class they are declared or inside inner classes. private keyword is one of four access modifier  provided by Java and its a most restrictive among all four e.g. public, default(package), protected and private. Though there is no access modifier called package, rather its a default access level provided by Java. In this Java tutorial we will see why should we always make members of class by default as private and answer to one of popular Java interview question can override private methods in Java.