From Java to Kotlin: Taking Development to the Next Level

Content:

• What is Kotlin
• Where is it used
• Kotlin code examples
• Where to start learning

What is Kotlin

Kotlin is a statically typed language created by JetBrains programmers to make development easier and improve their productivity. Kotlin is based on the Java Virtual Machine (JVM), which runs Java applications and provides a powerful toolkit for creating a variety of programs.

The history of Kotlin's creation and development began in 2010. For several years, a team of developers from JetBrains worked on creating a new environment that would help optimize the Java programming process. They sought to maintain compatibility with Java, but add new functionality and simplify the syntax.

In 2011, JetBrains released Kotlin as an open source project to gather feedback from the developer community. Over the course of its existence, the language has gained great popularity, and in 2017, it was even designated by Google as the official language for Android app development. Since then, Kotlin has continued to evolve and become increasingly widespread.

Some of the main features and advantages include:

• Clean and understandable syntax.The language offers a concise and intuitive syntax, which makes the code easy to read and compact to write.
• Full compatibility with Java. This means that current Java code works in Kotlin projects and vice versa. This allows you to seamlessly migrate from Java to Kotlin, preserving and expanding your codebase.
• Type safety. Kotlin provides static type checking, which allows you to find errors at compile time, rather than at runtime. This helps prevent many bugs and improves code reliability.
• Language extensions.A powerful language extension mechanism (extension functions) allows you to add new functionality to existing classes without changing their source code. This improves Kotlin's flexibility and makes your code more precise.
• Multiple platform support.Kotlin is used for development not only for the JVM. This language is used to create mobile applications, develop server solutions, and write programs for other platforms.

It is because of its demand and multifunctionality that Kotlin has gained an active and friendly community of developers, whose efforts are focused on its development, expanding libraries, tools, and resources.

Where Kotlin is used

Kotlin has become a popular language environment used to create many applications, from mobile software on Android to large-scale and, importantly, easily scalable server solutions. Let's take a closer look at the different types of development where Kotlin is especially popular:

• Android app development.Kotlin offers many advantages: excellent code readability, type safety, and numerous language extensions available. This makes the development process efficient and enjoyable for developers. Many well-known applications such as Twitter or Pinterest use Kotlin for their Android solutions.
• Server-side development.The language is used to create powerful and scalable server-side applications. Thanks to its performance, type safety, and complete compatibility with Java, Kotlin has become the optimal choice for developing web applications, microservices, and other server-side solutions. On the server side, it is used by Adobe products and Jira cloud services.
• Development for other platforms.Using Kotlin Multiplatform libraries, you can develop applications that run and run reliably on iOS, macOS, Windows, and Linux using shared code. This reduces development time and supports multiple application versions. The language is also used for software development on the JVM, JavaScript and Native/Kotlin platforms.

Today, Kotlin continues to attract more and more software development professionals from various companies and projects. Here are some examples of well-known companies that work with Kotlin:

• JetBrains. The company that developed Kotlin actively uses this programming language for its products: IntelliJ IDEA, Kotlin Multiplatform and Kotlin/Native.
• Ozon. One of the largest online stores that specializes in selling goods of various categories. Ozon uses Kotlin to develop its mobile application.
• Evernote.An Android app for organizing and storing notes written in Kotlin.
• Pinterest.An Android platform for sharing ideas and inspiration, one of the first major players in the IT industry to switch to Kotlin.
• Uber.The largest international company providing taxi and transportation services uses Kotlin to develop Android applications.

Kotlin Code Examples

Syntax is the rules and norms of a programming language. It determines how to correctly format and compose program code, use keywords, operators, brackets, and other language elements. Kotlin's syntax is more concise, expressive, and understandable than other languages. This makes it easier to learn and write clean code, improves programmer productivity, reduces the likelihood of errors, and makes code more readable and maintainable.

It is through syntax that the programmer "explains" to the application runtime what the program should do. The syntax of this language is very similar to Java, which makes it easy to learn for developers familiar with Java or other JVM-based languages.

For example, for the simplest "Hello World!" program in Kotlin, you'll need to write just three lines of code, while in C++, you'll need as many as six. Here are some examples of how the syntax of this programming language works.

Printing Text on the Screen

To print text on the screen, we can use the "println()" function..

Example:

fun main() {

println(«Hello, world!»)

}

Result:The program will display the phrase "Hello, world" on the screen.

Declaring Variables

A variable is a place where you can store data. In Kotlin, you can declare a variable using the "var" or "val" keyword.

Example:

fun main() {

var name = «Anna»

val age = 25

println(«My name is $name and I am $age years old.»)

}

Result: The program will display the phrase «My name is Anna, and I am 25 years old.»

Conditional Statements

Conditional statements allow the program to make decisions based on certain conditions. For example, you can use the "if" and "else" statements for this.

Example:

fun main() {

val number = 10

if (number > 0) {

println(«The number is positive.»)

} else {

println(«The number is negative or equal to zero.»)

}

}

Result:If the number is greater than 0, the program will print "The number is positive", otherwise - "The number is negative or equal to zero."

Loops

Loops allow you to execute a specific block of code multiple times. In this language, you can use the "for" loop.

Example:

fun main() {

for (i in 1..5) {

println(«This is iteration number $i»)

}

}

Result: The program will output numbers from 1 to 5 (inclusive) on separate lines.

Classes

Classes are templates that describe objects and their properties. You can create a class using the "class" keyword. Example: class Person (val name: String, val age: Int) fun main() { val worker = Person('Alexey', 30) println(employee.name)

println(employee.age)

}

Result:The program will create an employee object of the Person class with the name "Alexey" and an age of 30. It will then print this employee's name and age to the screen.

Functions

Functions are blocks of code that can be called to perform a specific task. You can declare a function using the "fun" keyword.Example:

fun say hello(name: String) {

println(«Hello, $name!»)

}

fun main() {

say hello(«Alice»)

}

Result:The program will call the "say hello" function with the "Alice" argument and display the string "Hello, Alice!" on the screen.

And these are just a few examples of how to use the language. In practice, Kotlin offers many more features and capabilities, such as inheritance, interfaces, lambda expressions, and more.

Where to start learning Kotlin

To get started, we recommend reading the official documentation. It provides detailed information about the language and its capabilities. You can find it on the official Kotlin website or the Russian-language equivalent.or.

Also, you can find a lot of books, educational materials, and online courses on the Internet dedicated to language:

• D. Zhemerov, S. Isakova "Kotlin in Action" is a book that reveals all the nuances of the language and the features of its application in various development scenarios.
• Kotlin Koans — a series of practical exercises to help beginners master the basics of the language.
• Kotlin Bootcamp for Programmersis an online course provided by JetBrains that will help you quickly master the language.

The Skillbox.by editorial team recommends joining developer communities where you can exchange experiences and ask questions. There are several blogs, platforms, and forums where you can find such communities. Among them, the following have gained worldwide popularity:

• Kotlinlang Slack — on the corporate messenger platform.
• Kotlin subreddit - on the Reddit portal.
• Official Kotlin Blog— Follow news and updates from the community here.

Kotlin and its ecosystem are constantly evolving. It's important to stay up-to-date with the latest updates and new language features.If you're looking to enter the IT industry as a Kotlin programmer, consult the official documentation, books, and online courses, and join developer communities. And don't forget to practice by creating your own Kotlin projects.