Reactive Programming in Java: all you need to know
January 16, 2020

Software Development

Reactive Programming in Java: Top 10 Questions & Answers

By Olga Matuts

The term “Reactive Programming” first appeared in 1960. Today there is confusion around the RP definition, which increased when The Reactive Manifesto was proclaimed and represented “Reactive systems” with 4 principles (Responsibility, Resilience, Elasticity, and Message Driving) in 2014.

Let’s consider the most popular questions about reactive programming to understand its nature better.

#1. What is Reactive programming?

Reactive programming is the coding style, which is aimed to work with asynchronous data streams and a certain propagation of changes. Reactive programming is about making modifications to the execution environment in a specific order.

#2. What is meant by the specific propagation of change? 

In other words, what is the difference between the synchronous, asynchronous, and reactive approach?

Let’s consider the situation:

Tom wants to go to the movies with his friends, Kate and Jim. What should he do?

  • Tom goes to the ticket office and buys the tickets. After that, Tom goes to Kate’s home. Together with Kate, they go to Jim’s home, and finally, they all go to the cinema. This is a too long and not very productive process, which corresponds to the sync approach.
  • Tom orders a ticket to the nearest cinema, phones to his friends and goes to the movies. The film is about to start, so he enters alone. Kate has no time to buy a ticket, while Jim comes a bit later and buys a ticket on a different row. This situation illustrates the async method.
  • Tom orders all tickets online and phones to his friends. Though Tom, Kate, and Jim travel from different parts of the city, they meet and go to the movies together. We see that all asynchronous actions should be completed before the beginning of the next one, and this is an example of a reactive approach. 

#3. Reactive programming and reactive systems: what is the difference?

Reactive programming is about the programming style and reactive systems are the sets of certain design and architectural solutions that lead to the creation of highly effective web applications.  

Developers can use reactive programming in reactive systems. It is a winning hand that helps them to build a more responsive web application with low latency and efficient usage of resources.

#4. Why is reactive programming useful for Java?

Java as an example of old object-oriented programming requires using async processing when it works with a huge scope of data. Async processing, in turn, can make code more difficult to understand and harder to maintain. Reactive programming simplifies work with asynchronous processes, that’s why it is so needed if we want to build a fast and responsive system.

#5. What frameworks can developers use if they need reactive programming in Java?

The last release of Java, Java 8, tried to extend the built-in functionality, but it didn’t become popular with software developers. Yet, there are third-party solutions that work with Java perfectly. Such frameworks are regularly updated and easy to use. 

  • RxJava, the first extension for reactive programming in Java, works with all versions of this programming language since Java 6. With the help of this framework, developers can build asynchronous software using Java and Android Java.
  • Spring Reactor is a clear and easily understandable framework that can be used to create well-behaved applications with a large throughput. Spring Reactor allows developers to use features of Java 8, which makes this framework so popular.

#6. What are the main advantages of reactive programming?

Reactive programming has several obvious benefits, such as:

  • Increased performance. It is achieved through the possibility of processing large amounts of data quickly and efficiently.
  • Improved UX. A web application becomes more user-friendly and responsive.
  • Simplified updates. Readable and predictable code allows developers to make frequent modifications.

#7. Should all of the projects use reactive programming?

It is no need to complicate the code of a simple website. It will be a good choice if you are going to update your site, for example, with the possibility to leave comments or change the rating. Reactive programming will help with processing a large amount of data. Reactive components can be entered step by step without changing the entire programming model.

#8. In what cases can developers use reactive programming?

It will be the right solution in case of high-load and multi-user applications, for example:

  • social networks
  • games
  • audio or video applications

#9. Can developers use reactive programming in separate parts of applications?

Developers can use reactive programming in several parts of any applications if it is necessary. To give a few examples, reactive programming is applicable to:

  • server code for serving highly interactive UI elements;   
  • proxy servers;
  • artificial intelligence;
  • data streaming in real-time.

#10. How to begin using reactive programming in Java?

A Java developer should “regroup” to take the next level of logic, as it requires a lot of time and practical experience to get used to reactive programming. It is not about frameworks uploading and reading manuals. For a company, it will be the right solution to seek a specialist who can analyze your system and define the way, how to introduce reactive programming in the product with the greatest benefit.   

Reactive programming is a special style of coding, which assumes that all the changes are managed with the help of asynchronous data streaming. Reactive programming will be applicable when async processes over-elaborate the code in Java; if there is no such a necessity, using reactive programming will be extra. 

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