Difference between Inheritance and Polymorphism in Java and Object Oriented Programming

Both Inheritance and Polymorphism are key OOP concepts and similar to Abstraction and Encapsulation, they are also closely related to each other. Because of their similarities, many OOP programmers, especially beginners get confused between Inheritance and Polymorphism. Even though they are closely related and you need Inheritance to support runtime Polymorphism they are a totally different concept. Inheritance refers to the ability for classes or objects to inherit properties of other classes or interfaces. It means you can write code for common functionalities and reuse it at different places by just using Inheritance and not re-writing those codes again and again. For example, you can write code to

5 Must Read Books to become Software Architect or Solution Architect

I receive a lot of queries from senior Java developers, who aspire to become software architect or solution architect, like what can they do to become a software architect? Which books, resources, or certifications can help? And general queries like how much experience you need to become a software architect etc. In the past, I have been suggesting them individually about some books to read to expand their knowledge base and look at the software from architecture and design perspective, and this article is a compilation of many of such suggestions. Since a lot of books can confuse, I have only select 5 best and must-read books from the software architect's perspective.

Is it Possible to earn a Computer Science Degree Online in 2021?

A lot of my readers were asking this question, is it possible to get a computer science degree online? Do Coursera online degrees are worth it? How much is the charge? is it cheaper than any regular university degree? is it recognized worldwide? will I get employment using this degree, and how much time I need to spend daily, etc?  These are a lot of questions about online degrees but I have been receiving them for quite some time and now the frequency has even increased. The short answer to this question is, Yes, now it's possible to earn a Master of Computer Science degree 100% online. Things are changing in the education space and they are changing at a really fast speed.

Which Programming Books Would You Buy If you got 100$ to Spend?

Hello Guys, it's time to take a hypothetical question in Javarevisited. I love books and I have so many in my library and on my phone but this time, I am asking for your recommendations. Which programming book, would you love to buy, if you are given 100$ to spend? I know, when it comes to buying, people want the worth of their money, and that's why I am posting this question to you guys. Suppose you are looking for some books in a bookstore and suddenly salesman comes and say, at this particular minute, we are giving you 100$ FREE to buy any programming book.

Top 10 Advanced Java books for Intermediate and Experienced Developers

Hello guys, once you learn Java and done with reading some of the best known introductory books on Java and have a couple of years of experience under your belt, you would be hungry to transition from an intermediate Java developer to an expert Java programmer, also known as Java guru. This transition is not smooth, and I have seen many Java developers having 2 to 6 years of experience stuck where they are and have absolutely no knowledge of advanced topics like JVM internals, Concurrency, Garbage collection, and Performance tuning.

Top 5 Advanced SQL Books for Experienced Programmers - Best of lot, Must read

If you an experienced programmer and know how to write SQL queries and database fundamentals but want to take your SQL and database skills to the next level then you have a come to the right place. In this blog, I have shared a lot of free SQL books and courses you can use to start your SQL journey. This is also the second article about SQL books, In the first part, I have shared some of the best SQL books which are essential to learning SQL queries and fundamentals of database like normalization, indexing, and other design stuff, if you haven't read it yet, I suggest to do it now. You will find some amazing books to start learning SQL.

10 Books Every Java Programmer Should Read - Best of Lot, Must Read

If you are a Java programmer and wondering what to read to improve your knowledge of Java and become a better Java developer, then you have come to the right place. In this article, I am going to share some of the best Java books ever written. In fact, this is my list of all-time great Java books. They have withstood the test of time and emerges as more and more successful years after years. It doesn't matter if you read them this year or reading them next year, you are always going to learn a lot, and that's why I call them all-time great books.

Top 5 Books to Learn Groovy for Java Developers - Best Of Lot, Must Read

Groovy is a programming language that is specially created for Java developers with a view to being a fast-paced, scripting companion to Java. It aims to increase the productivity of Java developers by simplifying Java code and removing unnecessary boilerplate. Groovy not only present a succinct and easy to read syntax but also provide a much more elegant and convenient API than Java for common stuff. For example, a Groovy file can do in 50 lines what a Java source code does in 500 lines. You can declare an array as [] and map as [: ] which really makes code full of data without much syntax. Because of this property, Groovy is heavily used in unit testing of Java application. Some popular unit testing frameworks like Spock is also built on Groovy.

How to find all unchecked checkboxes from a page using jQuery? Example Tutorial

Hello guys, In the last tutorial, you have learned how to get all the checked checkboxes from a page using jQuery, but sometimes you also need all the checkboxes which are not selected. In this tutorial, you will learn that. If you remember, we have used the:checked pseudo selector to get all checked checkboxes, but, unfortunately, there is nothing like the :unchecked selector in jQuery, so using that will result in the syntax error. Even the!:checked or :!checked will not work, instead, you need to use not() jQuery selector, which does the negation job.

7 Examples to Read File into a byte array in Java

Hello guys, Java programmers often face scenarios in real-world programming, where they need to load data from a file into a byte array, it could be text or binary file. One example is to convert the contents of a file into String for display. Unfortunately, Java's File class, which is used to represent both files and directories, doesn't have a method say toByteArray(). It only holds path and allows you to perform certain operations like opening and closing file, but doesn't allow you to directly convert File to a byte array. Anyway, no need to worry as there are several other ways to read File into a byte array and you will learn those in this Java file tutorial.

Top 5 Books to learn UML (Unified Modeling Language) for Java Developers - Best of Lot, Must Read

The UML stands for Unified Modelling language and it is one of the great tools for Object-oriented design. It allows you to create several diagrams like class diagram, sequence diagram, object diagram, etc, which helps you to understand your system better.  The UML also helps you to convey your thoughts and design to peers and team members before implementation. Since a picture is worth a thousand words, those interactions often help you to find shortcomings and loopholes in your software design very early. That's actually the reason I use UML in our projects. Btw, I didn't know about UML or UML diagrams when I first started Java development.

Top 5 FREE eBooks to Learn jQuery Online or download PDF

Hello guys, Everybody loves free resources, don't you? Well, I do and that's why I am always in search of good free resources like eBooks and training courses. In the last article, I have shared some of the free JavaScript books and this time I am sharing a couple of good free eBooks to learn jQuery. JQuery is one of the most important skills in today's internet world. It is the JavaScript library that has changed the face of websites, they are now more interactive and smooth than ever before. The Internet is also not short of free resources and when it comes to learning jQuery, you will find thousands of articles and tens of eBooks, but not all resources are good. Some of them are not up-to-date and many of them contain incorrect information, hence choosing a good resource is vital.

10 Things to Remember while doing Database Server Migration

Hello guys, recently, I have to work on a high profile project which involves migrating a live database from one server to another server as part of their data center exit program. This was one of the critical projects to pull off because we can't afford any mishap or data loss or production outage. There are a lot of things that I learned and would like to share with you guys. All these lessons not just apply to migrate databases like Microsoft SQL Server, Oracle, or MySQL database from one server to another but to any production process, you are migrating from another server. These are the things we learn from experience but as I have said in the past, you can only learn a few things

3 Books to Learn Eclipse IDE for Java JEE Programmers - Best of Lot

In order to become a good Java developer solid knowledge of Eclipse IDE, or whatever IDE you use, like Netbeans or IntelliJIDea, is a must. Java has been blessed with excellent tooling which turbo-charge application development. IDEs or Integrated Development Environment allows you to code, run, test, and debug from just one tool. They are an immense productivity booster. Since I have started Java development coding in Notepad, TextPad, and JCreator, I know how it feels to have the power of IDEs with you. There are three big IDEs in Java world, Eclipse, NetBeans and IntelliJIDEA. The first two are free, and the third one requires the license. I use Eclipse, and it's also the most popular IDE in Java world.

Top 2 Books for OCPJP8 Certification - Java 8 1Z0-809, 810, 813 Exam

This is the second part of the best books for Java 8 certifications. Since you need to pass two exams, OCAJP8 and OCPJP8, to become a Java SE 8 certified developer, I have shared some of the best OCAJP8 books in the last article. In this article, I will tell you more about the second exam, OCPJP8, and suggest the best books to prepare OCPJP8. This exam is known as a professional level exam, and it's more stringent than the associate level exam. The OCPJP8 stands for Oracle Certified Professional Java Programmer. The exam code for this certification is 1Z0-809.

[The AZ-303 Exam Preparation Guide] - How to Crack Microsoft Azure Solution Architect Certification Exam in 2021?

Hello guys, based on the new Azure role-based certification path, the Microsoft AZ-303 exam is the main step towards becoming a Microsoft Certified Azure Solutions Architect. Earlier, I have shared a few tips, courses, and practice tests to pass the AZ 104, AZ-900, or Microsoft Azure Fundamentals exam and today, I'll talk about AZ-303 or Azure Solution Architect certification exam. This exam requires experienced candidates with skills in roles including Azure development, Azure administration, and DevOps. In addition, they must have expert-level skills in at least one of these areas. However, observing these requirements, some of you may think that it would be completely impossible to pass a Microsoft AZ-303 Architect Technologies exam preparation.

Top 5 Java SE 8 Certification Books - Best of Lot Must Read

Hello guys, If you are preparing for Oracle Certified Associate, Java SE 8 Programmer, also known as Java SE 8 Programmer I or OCAJP 8 exam and looking for some good resources then you have come to the right place. Earlier, I have shared some courses, and practice tests to pass the Java SE 8 certification. Actually, I have been sharing some of the most useful resources for Java 8 certification aspirants ever since the exam was launched. You can find a lot of this exam and essential resources in this blog. To continue that tradition, I am going to share some of the best books to crack the Java SE certification like OCAJP 8 (1Z0-808)  and OCPJP 8 (1Z0-89). Yes, you need to pass two exams to become Java 8 certified professional.

How to Crack Microsoft Azure Fundamentals (AZ-900) Cloud Certification in 2021

Cloud computing skills are in demand and companies are increasingly looking for people who know and worked in public cloud platforms like AWSGCP, and Microsoft Azure. If you are looking to get started in Cloud Computing, particularly on the Microsoft Azure side then AZ-900 or Azure Fundamentals certification is probably the best way to start. You will not only learn about Azure but also learn essential Cloud Computing fundamentals like storage, network, compute, and memory among all things. You will also learn about things like IaaS (Infrastructure as a Service), PaaS (Platform as a Service) and SaaS (Software as a Service), Sales, and Pricing, which are very important for both technical and non-technical IT professionals.

Top 10 Java Programming Books from Beginner to Expert - Best of lot, Must Read

These top Java programming books are some of the good books to learn Java and I would say some of them are simply the best Java books ever published. Whenever a programmer starts learning Java programming language, the first question he asks is "Which book should I refer to learn Java?", or "What is the best book to learn Java for beginners?" or "Can you tell me some good books to learn Java?" .That itself says how important Java books are for programmers especially beginners.  Despite having so many free resources available in Java, like tutorials, online courses, tips, blogs and code examples, Java books have their own place because of two reasons:
  • They are written by programmers who are the authority in the subject
  • They cover the subject with more details and explanation.

Clean Architecture by Robert C. Martin - Book Review - A Must Read Book to Become Software Architect

Hello Guys, today, I am very excited to talk about a nice book (Clean Architecture: A Craftsman's Guide to Software Structure and Design) from one of my favorite author of programming books, you guessed it right, Uncle Bob. The same Uncle Bob (aka Robert Martin) who brought you the Clean Code and Clean Coder has been at it again. It's been a long time since I last read an Uncle Bob and somehow I wasn't aware of this book. It comes to me as a surprise yesterday when one of the colleagues mentioned it and I didn't take time to realize that I need to buy and read this book. I just cursed myself that why I didn't know about this book before, it is still new but given I love to read his books, it's just a miss for me.

Top 5 Books to Learn SQL and Database Design for Programmers and DBAs - Best of Lot

The database design and modeling are one of those topics which rarely get the attention they deserve, especially at the start of the project, but once things have gone out of hand, then everybody talks about them. Comments like - this database is designed poorly, the schema is not performing well, you cannot add a new column easily, etc. becomes very common. The most problem with database design is that it is mainly done by application developers like Java or C++ developer who knows SQL, but they are not the expert on how to design tables and schema. The Database admins or DBAs know database and SQL better than application programmers, but they mostly focus on the admin part of the database, preferably on application part like designing tables and relations between them, which is left to the application developer.

6 Date and Calendar Details Every Java Programmer Should Know

Hello guys, to appreciate the brilliance of the new Date and Time API introduced in Java 8, you must remember nasty problems you have faced. Another reason for this article is that even though Java is ready with the new, shiny, and carefully designed Date and time API, your project is probably not. Most of the prominent organizations that use Java at large scales, like Investment banks, Insurance companies, major E-commerce giants, are quite reluctant to upgrade. There are many firms, both big and small that are still running on Java 5 and expect to migrate to Java 6 in a couple of years.

SQL GROUP BY and HAVING Example - Write SQL Query to find Duplicate Emails - LeetCode Solution

Write a SQL query to find all duplicate emails in a table named Person.

+----+---------+
| Id | Email   |
+----+---------+
| 1  | a@b.com |
| 2  | c@d.com |
| 3  | a@b.com |
+----+---------+

For example, your query should return the following for the above table:

+---------+
| Email   |
+---------+
| a@b.com |
+---------+

Note: All emails are in lowercase.

Top 4 Books to learn Oracle PL/SQL Programming - Best, Must Read

In last summer, I had to work on a Java project which was using the Oracle database at their backend. The project was a mix of Java code with Oracle PL/SQL stored procedures, where Stored procedures were quite big and complex to read. I had not worked on Oracle for a couple of years and almost forget whatever I knew before. So, to revise, update and re-learn and I looked over some of the books and online courses like The Complete Oracle SQL Certification Course which helped me a lot. In my quest to revise and re-learn Oracle SQL, I also find lots of their used books on Oracle PL/SQL which are both interesting to read as well as provides a great wealth of information to any programmer.

50+ Java Collection and Generics Interview Questions with Answers

Hello guys, If you are preparing for Java interviews then you may know that Java Generics and Collections are two of the most important topics, particularly Generics where some of the trickiest Java questions can be asked. They are also used to gauge your experience and depth of your Java knowledge, hence it's imperative for both beginners and experienced Java programmers to prepare this topic well. While Java Collection framework provides an implementation of some command data structures like ListSetArray, Hash table, Queue, Stack, PriorityQueue, etc, Generics provides Type safety.

Top 5 books to learn Agile and Scrum for Programmers - Best of lot, Must Read

When I started my career, it was all waterfall model. You try, fail, and then with every version you get an improved version of the software. I pretty much used to this model of software development until I was introduced to Agile development methodologies in my next company. I was confused about Agile as some people say its Scrum and Sprint, other ways its XP and Kanban, etc. The confusion lasted for a long time because I was afraid of asking questions (afraid of being perceived as dumb and someone who wastes time on meetings) and only getting information in bits and pieces and I wasn't good at searching books at that time. From that experience, I learned that, when you have confusion and want to learn more about new technology, nothing is better than a book or online training courses to start with.

Top 5 Books to Learn Unit testing, JUnit and TDD in Java - Best of Lot

Hello guys, If you done some professional Java development then you know that Unit testing is a very, very important thing to learn to adapt. I would say this is the single most practice in my book, which differentiates an excellent programmer with a professional programmer. It's one way you can see how disciplined a programmer is? It's also the best way to write clean code; a code that can stand the test of time, a code that is flexible enough to accommodate future changes and a code that you don't afraid of while changing. Despite several efforts of promoting unit testing by programming community and emphasizing unit testing by many notable programmers, it's still one of the lacking practice.

How to Crack Microsoft AZ-103 / AZ-104 Azure Administrator Associate Certification Exam

Hello guys, if you are looking for cloud certifications in 2021 then Microsoft Azure Cloud certification can be a great addition to your profile. Earlier, I have shared a few tips, courses, and practice tests to pass the AZ-900 or Microsoft Azure Fundamentals exam and today, I'll talk about AZ-103 or Microsoft Azure Administrator certification.  Microsoft launched two new certifications AZ-100 and AZ-101. These are the replacement of 70-535 for the new role-based Microsoft Azure Administrator Certification. On May 1, 2019, both AZ-100 and AZ-101 exams have been replaced by the AZ-103 exam.