Do you want to learn Java, and confused from where to start first? As we know there are many topics in Java. So, to help you out from the confusion which topics are important and need to learn first, here we have listed the important topics to learn in Advanced Java (Java EE). We have provided some basic introduction to these topics. Here are the important topics to learn Advance Java (Java EE):
Core Java Concepts: Object Oriented Programming and Design Patterns
Why we have given a topic number “Zero” for the first most important topic to learn Advanced Java, it is because without Core Java concept we cannot go ahead, you need to have detailed knowledge about Core Java.
As there is a saying, “if you want to write sentences, first you need to learn Alphabets”, here, Core Java is the “Alphabets” and Advance Java is the “word”. So you need to have a good knowledge of Core Java before going ahead in Advance Java.
Object Oriented programming deals with concepts like class, object, Inheritance, Encapsulation, Abstraction, and Polymorphism. Many popular programming languages follow object-oriented programming paradigm, C++, C#, Ruby, and Java are some examples of the Object Oriented language.
In Java object-based application is based on declaring classes, creating objects from them and interaction between these objects. To go further ahead on Advanced Java, you need to understand Object Oriented Programming language concepts such as Inheritance, Encapsulation, Abstraction, and Polymorphism.
A well-proven solution for solving some specific task is known as Design patterns. Design patterns help you to make your code more flexible, reusable and maintainable. As Java internally follows Design Pattern, it is the most important part of Java. There are different design patterns available in Java to solve different problems. Every design pattern has some specification or set of rules for solving certain problems.
Design patterns are not related to any specific programming language, as they are programming language independent strategies for solving similar types of object-oriented design problems. So, for becoming a professional programmer or for learning Advanced Java, you must know at least some popular design patterns.
Advanced Java – Important Topics:
Here are some of the important topics you need to know to be an advanced Java developer:
1. Build tools, Example: Maven, Ant, Jenkins/Hudson, Gradle
The important topic for going ahead in Advanced Java is Build tools. What is the build tools? Well, these are the programs which automate the creation of executable applications from source code. The build tool does the compiling, linking and packaging the code into a usable or executable form.
It is a difficult task to keep track of what needs to be built, in what sequence or what dependencies there are in the building process in large projects for developers. This is where Build tools come in. These tools automate the building process and make it more consistent.
Build tools to take your source code and compile it as an executable program. Build tools nowadays bring more than just building your app, as there are features like dependency management as well. There are mainly three build tools: Ant, Maven, and Gradle, whereas, Jenkins or Hudson is the continuous integration tool which is just much more than the build tool.
In Jenkins or Hudson, you can set up your CI environment and automatically build, test and deploy Java projects. Jenkins is an open source whereas Hudson is closed source continuous integration tool. These build tools create deliverable like JAR file or WAR file for deployment from Java source.
2. Container Management tools, Example: Docker, Kubernetes
Next important topic you should learn in Java EE is about container management tools. A component that can contain other components inside itself is known as a container. The best example of a container is an applet. Container and its platform provide much more advantages over traditional virtualization.
There is no need for the guest OS to perform Isolation as it is done on the kernel level. This makes the containers more efficient, lightweight and faster. The encapsulation of applications in a self-contained environment, provides scalability, quicker deployments and closer parity between development environments.
Docker is the most popular container platform. There is a Docker Engine which is a runtime and allows you to build and run containers and includes Docker Hub, which is a cloud-based repository for storing and sharing images. Docker gives you the power to build and run any app on any platform but yet there is something missing.
If you want to run multiple containers across multiple machines, you cannot do using Docker so we need a container orchestration platform, like Kubernetes, Mesos or Docker Swarm. Docker Swarm is the own native clustering system of Docker. Docker Swarm has the advantage as it is tightly integrated into the Docker ecosystem, and uses its own API.
Whereas Kubernetes is the open source container orchestrator which was developed at Google. In the field of orchestrating, Kubernetes is popular. Kubernetes is the most used standardized means of orchestrating containers which deploy distributed applications. Kubernetes is open source highly modular and has a vibrant community whereas Docker Swarm has a smaller community compared to Kubernetes.
3. Version-control system + repository hosting service, Example: Git + Github
What is the Version control system? The system that keeps the record of the modifications to a file or set of files over time so that you can recall specific versions later is known as Version Control System (VCS). These are the software tools that help to manage changes to source code over time.
If any mistake is made, developers can turn back the clock and compare earlier versions of the code using version control system, in which all the modifications are stored in a special kind of database.
Using a Version Control System (VCS), you can easily revert the entire project back to the previous state or just a selected file to a previous state. A VCS also generally means that if something goes wrong or lose files, you can easily recover, compare changes over time and you can also see who last modified something that might be causing a problem.
There are many popular VCS tools in use today, such as Git, Mercurial, Bazaar, etc. Git is a Distributed version control system, known as DVCS. In Distributed VCS, different branches hold different parts of the code as there is no one centralized code base to pull from. Other version control systems, such as SVN and CVS, use centralized version control, meaning that only one master copy of the software is used.
As many other most popular VCS systems, Git is also free and open source. Git is a fast and efficient version control system, and many major open-source projects use Git. Git is mostly used version control system by the Web development community.
GitLab and GitHub are web-based Git repositories. Git repository contains a set of commit objects and a set of references to commit objects. Github and other git repositories are used as a central place where developers store, share, test and collaborate on web projects. GitHub is a most popular hosting service for Git repositories.
As the version control system, Git, is the tool whereas GitHub or Gitlab is the services for the projects that use Git. In Github, projects on the platform are publicly available. However, to make your project private, (GitHub users now get unlimited free private projects with up to three collaborators) a paid GitHub plan starting at $7 per user per month for individual developers and $9 for per user per month in teams will be required.
The GitLab offers free private repositories for open source projects. But if you want access to more functionalities, you’ll need to have paid version, that starts at $4 per user per month.
4. Testing Framework, Example: JUnit Test + Mockito
The software testing method to determine if the individual units of source codes, such as functions, methods, and class are fit for use or not by testing them is known as Unit Testing. A unit is also considered as the smallest testable part of an application.
JUnit is a widely used unit testing framework for the Java programming language. In the development of test-driven development, JUnit has been an important part. JUnit is one of the important unit testing frameworks which originated with SUnit and is collectively known as xUnit.
You can use this automation framework for both unit testing and UI testing. JUnit, with different Annotations, helps us to define the flow of execution of our code.
Mockito is a JAVA-based library that is used for unit testing of JAVA applications effectively. Mockito mocks interfaces which allow a dummy functionality to be added to a mock interface which can be used in unit testing.
The word “Mocking” in Programming means mimicking the behavior of a real object. This idea is used in unit testing so that mock objects can mimic real objects in a controlled fashion. Basically, these mock objects are a simulated version of the original object which is created in a program to test the behavior of another object. The mocking of an object is a technique of unit testing in isolation by simulating its dependent units.
5. Object Relational Mapping: JPA + Hibernate
A programming ability to convert data from object type to relational type and vice versa is the main feature of ORM. ORM does mapping or binding of an object to its data in the database.
The data, type of data and its relations with its self-entity or any other entity are considered while mapping. In case of same data in Java programming, you will encounter abstraction, inheritance, composition, identity, etc and converting the table format data to an object often leads to mismatch which can be solved by using ORM.
The Java Persistence API (JPA) is a Java specification for persisting, using and managing data between objects or classes in Java and with a relational database.
As JPA is just a specification, Hibernate is one of the actual JPA providers. JPA or Java Persistence API is a standard specification which implements ORM whereas Hibernate actually implements ORM framework. Popular implementations of ORM framework are Hibernate, EclipseLink and Apache OpenJPA, among them Hibernate is one of the most popular Object/Relational Mapping (ORM) framework in the Java world.
Hibernate simplifies the development of Java application to interact with the database and is an open source, lightweight, ORM (Object Relational Mapping) tool. It allows mapping the object structures of normal Java classes to the relational structure of a database.
It becomes easier to store data from object instances in memory to a persistent data store and use them back into the same object structure with the help of ORM. Using Hibernate, we can abstract from the specific product used to store data which lets you use the same Java code with different database products. This removes the need to write code that handles the differences between the supported products.
6. Spring framework : Spring JDBC + Spring boot + Spring MVC + Spring Security + Spring Transaction etc
Another important topic to learn in Java EE is about MVC, JDBC and many modules of spring framework.
The Spring Framework is an application framework having many different modules that provide a wide range of services. Spring framework is an inversion of control container for the Java platform. The spring framework can be used by any Java application. But for developing web application on top of the Java EE platform, there are extensions too. Spring framework makes it easy to build the mobile application from desktop to Web.
Spring JDBC is an abstraction framework for JDBC. It removes the exception handling. Spring JDBC framework provides easier access to data sources and parsing of SQL fetch results. Spring JDBC is a very helpful framework in many ways.
Spring Boot is a framework designed to ease the bootstrapping and development of new Spring application. The framework frees the developer from the need to define the boilerplate configuration by taking an opinionated approach to configurations.
In the ever-expanding rapid application development space, Spring Boot Framework aims to beat frontrunner by reducing Development, Unit Test and Integration Test time and easing the development of the Production ready web applications.
Spring Security is another Java and Java EE framework that provides authorization, authentication, and many other security features.
A Spring MVC is a Java framework that can be used for building web applications and follows the Model-View-Controller design pattern. With the help of DispatcherServlet, Spring MVC provides an elegant solution to use MVC in spring framework.
The Spring MVC framework provides the MVC architecture and ready components from which we can develop flexible and loosely coupled web applications. All basic features of a core spring framework like Inversion of Control, Dependency Injection, etc are implemented by the Spring MVC framework.
Spring’s transaction management framework provides an abstraction mechanism to the Java platform. Spring transaction management can help in working with local and global transactions and with nested transactions. You can work in almost all environments of the Java platform using Spring Transaction Management framework. It is better than Java Transactions API (JTA).
Spring’s Remote Access framework is an abstraction for various Remote Procedure Call (RPC) based technologies. It works both for connecting client and marshaling objects on servers. Using this framework, you can easily configure and use RPC based technologies. The Spring Remote Access framework also provides fault-recovery so it can automatically reconnect after failure in connections.
7. Web Services, Example: Rest, Soap
Web service makes itself available over the internet and uses a standardized XML messaging system which is used to encode all communications to a web service.
With the help of web services, various applications can communicate with each other and share data and services among themselves. Web services make the application platform and technology independent.
There are two types of Web services: Simple Object Access Protocol (SOAP) and Representational State Transfer (REST).
REST is a set of principles by which data can be transmitted over a standardized interface such as HTTP. There’s no additional messaging layer in REST. REST only focuses on design rules for creating stateless services. Using the unique Uniform Resources Identifiers, a client can access the resource and returns a representation of the resource.
SOAP defines a standard communication set of rules for XML-based message exchange. It’s a platform and language independent. As it uses XML, the server can be based on JAVA and client can use .NET or PHP and vice versa. Different protocols such as HTTP and SMTP, are used by SOAP. SOAP model can tunnel across firewalls and proxies without having any modifications to the SOAP protocol while using the standard HTTP protocol.
8. Logging Framework, Example: Log4J, SLF4j
Logging refers to the recording of activity. Logging is a common issue for developers which refers to the recording activity. A Logging framework is a computer data logging package. There are many frameworks which can ease and standardize the process of logging for the Java platform. Some of them are Log4j, Logbook, etc.
Apache Log4j 2, an upgrade to Log4j, is a logging framework that provides many of the improvements available in Logback. It has fixed some problems in Logback’s architecture. The asynchronous logging feature in Log4j2 improves performance, especially in multi-threaded applications.
A logbook is a Java library used for logging in various client and server-side technologies. Servlet containers, Apache’s HTTP client, and other frameworks are also supported by Logbook and have an auto-configuration for Spring Boot.
The Simple Logging Facade for Java (SLF4J) is an abstraction for various logging frameworks, such as logback, java.util.logging and log4j. It allows the end-user to use the desired logging framework at deployment time. SLF4J is Simple Logging Facade for Java and not a logging component. SLF4J is only an abstraction layer to an underlying logging component and does not do the actual logging.
9. Database, Example: MongoDB, SQL, MySQL
There are different popular database that is used in Java EE as the back-end database. MongoDB is a simple, dynamic, object-oriented and scalable NoSQL database. It is based on the NoSQL document store model and the data objects are stored as separate documents inside a collection. MongoDB aims to implement a data store that provides high performance, high availability, and automatic scaling.
SQL which is Structured Query language is used to communicate with a database. MySQL and MS SQL are highly popular relational database management system (RDBMS). MySQL is developed by Oracle Corporation whereas MS SQL is of Microsoft. Both MySQL and MS SQL stores data in tables and based on a structured query language (SQL) for database access.
10. Understanding of Cloud Computing, Example: AWS, Azure
Cloud computing is shared configurable computer system resources. The higher-level services can be rapidly provisioned with minimal management effort using cloud computing over the Internet. It fully relies on sharing of resources to have coherence and economies of scale. Cloud data are similar to a public utility which can be accessed and used to develop or run the application.
There are different cloud computing platforms like AWS and Azure.
Amazon Web Services (AWS) is a cloud computing platform provided by Amazon whereas Azure is a cloud computing platform provided by Microsoft. You can build and run Java apps in the cloud using different applications and data services.
The last but not the least topic you need to learn for Java EE is to have an understanding of FrontEnd. Front-end development is used to provide the visual display that the end-user of a website will experience.
12. And many more…
These lists are not sufficient itself, to be an advanced Java developer you need to learn a lot of other frameworks, tool, and technology. 🙂