Java Developer RoadMap — 2021
Hi guys, let’s explore this Java developer roadmap together and find out what tools, frameworks, libraries, APIs, tools, and skills you can learn to become a professional Java developer in 2021.
1. Tools
The tools section is divided into different sections. First, your IDE, which is your primary tool and can do almost everything you asked for like compile, run, debug, profile, test, compare files and code, refactoring, and much more.
1.1 IDEs
For Java Developers, there are two main IDES, Eclipse and IntelliJIDEA, you can choose any one of them as I have used Eclipse most in my life but I am currently working in IntelliJIDEA so I love both of them, but most of the Java developer I know they work in IDEA.
I suggest you master IDEA shortcuts, views, and all other features it offers to become a true Java Master and if you need a resource, I think IntelliJ IDEA Tricks to Boost Productivity for Java Devs is a great place to start with.
1.2 Build Tools
The second part is the build tool, which you need to build and deploy your projects like Maven and Gradle. Any one of these would be enough. I have just listed ANT, but that’s for legacy projects. For all new Java projects, prefer Gradle, it’s much more concise than Maven.
If you want to learn both Maven and Gradle, there are not many resources available. If you ask me, I recommend Apache Maven: Beginner to Guru by John Thompson on Udemy.
And, if you are keen to learn Gradle, I suggest you check out Gradle for Java Developers by another great Udemy instructor, Bharat Thippireddy.
1.3 Containers and DevOps Tools
And, the third and most crucial part includes containers like Docker and Kubernetes, CI/CD tools like Jenkins and TeamCity, and Infrastructure automation tools like Ansible.
Out of these Docker is the most important because it makes it easy to set up your development environment as well as it also makes the Deployment of Java Microservices easier.
Kubernetes is a next-level tool and not really needed for all JAva developers, particularly if you are not in DevOps and managing things like scaling and deployment but it’s good to know from a knowledge perspective.
I suggest having good knowledge of Docker and basic knowledge of Kubernetes for Java developers and if you need resources, I recommend Maximillian SchwaurzMuller’s Docker & Kubernetes: The Practical Guide course on Udemy. You can learn both of these tools in one course.
If you are interested in learning about these tools, here are some useful courses to learn to build tools and IDEs
2. Java APIs
The next important thing to learn is JDK APIs, which are very, very important for any Java developer. This is quite a big section, and that’s why it’s divided into core areas like Java Collections framework, Java Concurrency, Java IO, and Java 8 APIs, let’s explore each of them
2.1 Java Collections Framework
This is one of the most essential Java API every Java developer should learn. This API provides implementations of standard data structure in Java-like linked list, set, stack, queue, hash table, priority queue, and others.
At least you should know about all everyday objects like ArrayList, HashMap, HashSet, LinkedHashSet, TreeSet, etc. Each of them has its different property like ArrayList is a dynamic array that can grow, HashMap is a standard implementation of the hash table and can be used to store key-value pairs.
Similarly, HashSet is a set implementation that doesn’t allow duplicate elements. I strongly suggest you check Java Fundamentals: Collections course by Richard Warburton on Pluralsight to learn Java Collection Framework in depth.
2.2 Java Concurrency
After Java Collections, the next, most crucial API in Java is about multithreading and concurrency, and I firmly believe that if you want to be a competent Java developer, you must have a solid understanding and command of Java Concurrency API.
You should not only have an in-depth understanding of fundamental concepts like Thread, Runnable, Object locking, and Synchronization, but you should also be familiar with concepts like deadlock, livelock, race conditions, and how to deal with them.
You should also learn about advanced Java concepts like synchronizers added on Java 5 and subsequent versions, I mean CyclicBarrier, CountDownLatch, Phaser, and CompleteableFuture, etc., along with Futures and how to perform the async operation in Java.
I know, it’s a lot of stuff, and that’s why I suggest you join an in-depth course like Java Concurrency in Practice bundle from Heinz Kabutz, a Java Champion, and authority when it comes to concurrency and design patterns. This course is a bit expensive, but you will learn a lot more concepts in-depth, which makes it completely worth your time and money.
On the other hand, if the price is an issue, you can also check this Udemy course — Concurrency, Multithreading, and Parallel Computing in Java which won’t cost you more than $10 if you get it on Udemy flash sales which happens every month. This is also an excellent course to learn Java concurrency and multithreading in Java.
2.3 Java IO
I have interviewed more than 100+ Java programmers, and I have noticed one pattern; they all have very little knowledge of Java IO and NIO APIs as compared to Java Collections and Java Multithreading API. I can understand that many people spend a lot of time learning those two APIs, but you cannot leave behind these critical APIs.
If you have to code a real-world, core Java application, you will need to use classes like File, InputStream, OutputStream, Reader, Writer from the java.io package, which is the core of the Java IO API. Similarly, you also need to know about ByteBuffer, FileChannel, Selector, and other critical classes from java.nio API, if you want to write a socket-based application.
Unfortunately, there are not many dedicated resources on teaching Java IO and Java NIO API, but The Complete Java Masterclass is a great resource to master this API. You will find a lot of essential concepts from this API in this course.
2.4 Java 8 Features
Now, the next and another necessary API, a Java programmer, should learn is the Java 8 features, which has completely changed the way Java is coded and programmed nowadays. To become a Java developer in 2021, you must know how to use a Lambda expression, Stream API, Optional classes, and a new Date and Time API.
Without knowing these APIs, it would be very tough to write a Java application in 2021. Most of the libraries also now stop supporting versions lower than Java 8, which means you have to learn Java 8 features now than later. It’s already 5 years since Java 8 was released, so you literally have no excuse left.
When it comes to learning Java 8 features, there are a lot of excellent resources available in the market. Still, if you already know Java, I suggest you choose the resource which only focuses on Java 8 features like the Java 8 for Experienced Developers: Lambdas, Stream API & Beyond course on Educative. This way, you can learn Java 8 in no time.
While Java 8 features are essential for Core Java developers, if you can, please learn all other new features introduced from Java 9 to Java 13 like Modules, var for local variables, static factory methods for collections, Text Block, String in Switch, and many more. If you need more resources, you can check out this list of courses to learn all new Java features in 2021.
3. Frameworks
The best thing about Java is that it has a vibrant ecosystem, which means there are a lot of frameworks and libraries for almost anything. Usually, I don’t suggest a Java developer learn a framework until he needs to use it in his project. Still, there are some frameworks and libraries, which I believe every Java developer should know like Spring, Spring Boot, Hibernate, Log4j, JUnit, etc.
3. 1 Spring Framework
If you want to become a Java developer in 2021, I strongly recommend you to learn Spring Framework first. This is one of the most popular Java frameworks, and literally, almost every single Java application I have worked on in the last 5 years, uses this framework.
Spring Framework encourages writing clean code, which is easier to test and maintain by providing you features like Dependency Injection and Inversion of Control. It also has a rich API for most of the day-to-day tasks, and that’s why every Java developer should learn the Spring framework.
And, if you want to learn the Spring framework, there is no better course than Spring Framework 5: Beginner to Guru. It covers Spring 5, the latest version of spring 5, and teaches Spring in a more hands-on way than any other course.
3.2 Hibernate
The second framework which I recommend every Java developer to learn is the Hibernate, which is based upon JPA (Java Persistence API). To be accurate, Hibernate came before JPA, but because JPA is a standard API to implement the persistence layer in Java, Hibernate implements it.
Now, why should you learn Hibernate? Well, because most of the Java applications you will work with will interact with Database, and it’s excruciating to deal with Database in Java using JDBC and without a proper framework like Hibernate.
It provides some of the essential features like Caching and Transaction out-of-the-box, which means you have more time to focus on your application logic, than implementing caching in your application. This seriously improves the performance of Java application, and so far, my most significant reason to use Hibernate.
Now, when it comes to learning Hibernate there are many great resources available in the market, but the Spring & Hibernate for Beginners course is my preferred one because you can kill two birds from one stone, you can learn both Spring and Hibernate in one class rather than joining separate courses for them.
Btw, if you truly want to master Hibernate or looking for an advanced Hibernate course then Vlad Mihalcea’s High-Performance Java Persistence book and the course is the best resource for anyone.
3.3 Spring Boot
This is another framework I recommend every Java developer to learn in 2021 and going forward. Spring Boot took Spring’s philosophy of simplification and made it easy to work with Spring itself. Just like Spring makes it easier to create a Java application, Spring Boot makes it easier to create a spring-based Java application.
Features like auto-configuration take away most of the pain associated with configuring the Spring application. Similarly, starter POM features grouped commonly used dependency into simple reusable POMs.
Now, if you want to learn Spring Boot, I strongly suggest you go through Learn Spring Boot in 100 Steps course; it’s one of the best and most up-to-date and also provide step-by-step guides for everyday things a Spring Boot developer needs to know.
3.4 Java Microservice Frameworks — MicroProfile, Micronaut, and Quarkus
While learning Spring Boot and Spring Cloud is sufficient for developing Microservices in Java, there is a couple of more advanced frameworks you can explore, like Eclipse’s Microprofile, Micronaut, and Quarkus.
3.4.1 Eclipse Microprofile
It’s an initiative that aims to optimize Enterprise Java for Microservice Architecture. It’s driven by Eclipse, one of the leading organizations of Java and the company behind popular Eclipse IDE.
The goal of Eclipse of MicroProfile is to define standard APIs for building microservices and deliver portable applications across multiple MicroProfile runtimes. The current version of Eclipse Microprofile is 3.2, and it’s a useful Java framework to learn in 2021.
3.4.3 Micronaut
This is another Java framework you can learn in 2021. Micronaut is a modern, JVM-based, full-stack framework for building modular, easily testable microservice and serverless applications.
It’s a polyglot framework and allows you to create an application using Java, Kotlin, or Groovy. Some of the key talking points of Micronaut are reduced startup time, blazing-fast throughput, and minimal memory footprint.
If you want to learn more about MicroNaut, you can also check out Learn Micronaut — cloud-native microservices with Java course on Udemy. There are not many courses but this one and MicroNaut documentation are sufficient to start developing applications with MicroNaut.
3.4.3 Quarkus
Quarkus is another promising framework for Java developers. It’s a Kubernetes Native Java stack tailored for OpenJDK HotSpot and GraalVM, crafted from the best-of-breed Java libraries and standards. Quarkus tailors your application for GraalVM and HotSpot to get Amazingly fast boot time and incredibly low RSS memory (not just heap size!).
It also provides instant scalability and high-density memory utilization in container orchestration platforms like Kubernetes using a technique called compile-time boot. You can also use both the familiar imperative code and the non-blocking reactive style when developing applications for Quarkus.
In short, one of the best platforms for Java developers to create an application and something worth learning in 2021 and if you want to learn Quarkus and need a resource then Quarkus Backend development with Java and GraalVM is a great one to start with.
4. Testing
Testing is an essential skill for any Java developer, particularly unit testing, integration testing, and automation testing. At the bare minimum, every Java developer should be familiar with JUnit and Mockito, two of the most popular Unit testing and Mock library.
If you know these two and know how to use them to effectively create a unit test, you will be a much better Java developer than without them.
There are more advanced libraries that also exist like Cucumber for Business-driven testing, Robot Framework for integration testing, but there is no substitute for JUnit, you will always need that.
When it comes to a mocking library, you have a couple of choices like PowerMock, Mockito, and EasyMock. Still, I strongly suggest you learn Mockito because it’s a vast library, and also many Java developers and companies are doing that. It is slowly becoming the standard library for creating mock objects in Java.
If you want to learn JUnit and Mockito from scratch, then I also suggest you join Learn Java Unit Testing with Junit & Mockito in the 30 Steps course by In28Minutes on Udemy. It’s a practical and hands-on course to get started with both these libraries.
If you need more options than you I have already shared a lot of resources like books and courses, you can check those to learn more.
5. Utility Libraries
The real power of Java lies in its vibrant ecosystem of open source libraries. You will find libraries to do almost anything in Java from logging to machine learning, from sending an HTTP request to parsing JSON, and much more.
Apart from that, Java is also lucky to have utility libraries like Apache Commons and Google Guava, these two libraries effectively complement JDK libraries. I have also shared a list of 20 Java APIs and libraries for Java developers.
I suggest you go through that list, chances are that you already half of them but if you don’t learn them they are very, very useful and help you to write better Java programs and deliver faster.
6. Database
Database access is an important part of many Java applications and thankfully Java comes with JDBC (Java Database Connectivity) API Which provides a standard set of APIs for connecting to any relational database.
As an application developer, you just need to know the API as all vendors provide an implementation of those APIs. You just need to include their JAR file into the classpath and your code will work fine.
By the way, JDBC is not the only option to interact with the database, there are open source libraries like JOOQ which can help you to write SQL queries in Java.
jOOQ generates Java code from your database and lets you build type-safe SQL queries through its fluent API
7. Desktop and Frontend
Java offers great APIs like Swing and Java FX for developing GUI clients. Swing was really popular a couple of years back but C# has now taken lead but Java FX is another popular Java API for developing GUI applications in Java.
If you want to develop a GUI application like NetBeans, one of the famous Java editors which are also written in Java then you can learn Java FX in 2021. I wouldn’t advise learning Swing unless you are working for a bank that is paying you thousands of dollars per month maintaining their Swing-based trading GUI.
If you want to learn Java FX in 2021 and need a resource then you can also check out the Java FX Concepts Bootcamp 2021 course on Udemy.
You can also build and deploy Java FX applications on Raspberry PI, one of the small but powerful computers. If you are interested in that,
has a great course Use Java and Java FX on a Raspberry PI for beginners. You can take a look at that course to start with.
That’s all about the Java Developer Roadmap — 2021. I think this is an best resource to learn Java in 2021 and become a better Java developer. I have kept it simple so that most people can follow it and only included the important stuff.
All the best for your Java Development Journey !! 😊🙌
