We will use IDEs, such as IntelliJ IDEA and Eclipse, to set up the project. A knowledge of working with these IDEs is helpful.

Kotlin offers many features of modern languages. It has null safety, a functional style of coding, non-verbose code, and is clean and easy when it comes to using Java's stream operations, including filter, map, reduce, and more. All of these can help to improve your development life cycle and productivity.

Kotlin was developed with the intention of adding features that are not found in existing JVM languages. It is a modern JVM language that has full interoperability with Java, ensuring that existing applications or services don't face any problems with coexisting with Kotlin. If we are familiar with functional paradigms, it will be easier to make use of the power of the language.

When we think of developing an application, Java is one of the programming languages that comes to mind for various reasons, including its robust and secure nature, and the independence of its platform. Most enterprise applications are built using Java, and this particular programming language has been around for more than 20 years.

Kotlin is designed to be interoperable with Java, meaning Kotlin can seamlessly co-exist with Java. We can add Kotlin to our existing applications and we can use Java-based frameworks for application development. With this bi-directional use of Kotlin, we can invoke Java constructs from Kotlin, or Kotlin constructs from Java.

Although Java and Kotlin are both JVM-based languages used for application development, there are several differences between them. Kotlin has addressed some of the limitations previously associated with Java...

Now that we have learned about the benefits that the Kotlin language offers, let's see how to configure Kotlin in a project. In this section, we will look at how to create a simple Kotlin project and a Maven project using IntelliJ IDEA.

It's easy to create a Kotlin-JVM project using IntelliJ IDEA by observing the following steps:

1. Click on File | New | Project.
2. In the New Project window, select Kotlin/JVM, and choose Next. This is shown in the following screenshot:

3. In the next wizard, specify the Project name and the Project location. Choose JDK and Kotlin runtime and click on Finish.

4. In the modules settings, click on Facets and add Kotlin to...

A program in execution that initiates long-running operations, such as file IO, network IO, or CPU- or GPU-intensive work, requires the invoker to block until the operations complete. Programming languages handle this via concurrency.

The JVM has support for concurrency. Java has had strong support for multithreading and concurrency since its first release. Any process that is running inside the JVM can create a number of threads to execute multiple tasks in an asynchronous fashion. However, developing concurrent code in an optimal and error-free manner and debugging it is really challenging. Java provides various constructs to write concurrent code and, along with other JVM languages and third-party libraries, has tried to come up with innovative and elegant ways to achieve concurrency.

Java 5 made a lot of progress with regard to writing concurrent applications...

We will now discuss how to work with Kotlin and Java in the project that we created.

In this section, we will learn how to use Kotlin in an existing Java project, and Java in an existing Kotlin project.

One of Kotlin's important features is its interoperability with Java. If we have an existing Java project, we can add new code in Kotlin or we can convert the existing Java code to Kotlin.

Let's look at an example of how to add Kotlin code to an existing Java project created using Maven. We have created a simple Maven project that has some code written in Java. This is shown here:

We can add Kotlin code to it as follows.

1. Right-click on src/main/java and...

In this chapter, we have discussed the following:

• What Kotlin offers and why it is a game changer in enterprise applications
• How Kotlin language compares with Java
• How to configure Kotlin in a project
• What Coroutines are
• Intermixing Kotlin and Java