Kotlin vs Java: Which Programming Language Should You Choose?

Kotlin is a modern JVM language which has fewer lines of code, null safety, coroutines whereas Java is a mature language with a big ecosystem around it. Kotlin is suggested by Google to use for Android application development, while Java is used traditionally to develop backend solutions for enterprises. Kotlin allows saving up to 40% of the code compared to Java and reducing development time greatly. If you decide to develop an Android app then Kotlin will suit you well; Java will be more suitable if you have any legacy corporate software.

What is Java?

Java is a programming language which served as a foundation for enterprise and mobile applications for almost thirty years now. It is an object-oriented class-based language whose philosophy is "write once, run everywhere" meaning that the same code can be run on any computer having JVM installed. That's why this language was very convenient for bank, government and enterprise-level software.

History of Java

The Java programming language was introduced in 1995 by Sun Microsystems. The founders included the well-known developer James Gosling. Initially, Java came out of a project aimed at creating an interactive TV but became popular thanks to the boom in the development of the Internet because of platform independence. Since 2010, the company Oracle has been controlling Java development after buying Sun Microsystems and producing new releases of the language with various improvements.

Key Features of Java

This language is statically typed and can reveal most of the issues before the execution of the program starts. It provides automatic memory management using garbage collection, a large set of libraries, a high level of backward compatibility meaning the previous code would run on a new version, multithreading.

Common Use Cases of Java

Java is utilized for developing Android applications, enterprise software, web servers, financial trading platforms. Besides, Java is used in big data technologies such as Hadoop and for API development.

What is Kotlin?

Kotlin is a modern programming language that operates in Java Virtual Machine and was created in order to solve some problems faced by programmers who use the Java programming language. Kotlin is highly compatible with Java because one can execute Java programs using Kotlin and vice versa. In 2017, Kotlin was officially adopted as a programming language for development of Android applications by Google. This was a milestone for the Kotlin programming language.

History of Kotlin

JetBrains is the company that has created the Kotlin programming language, which was first unveiled in 2016. The concept of developing Kotlin programming language was to come up with a programming language that was highly safe, redundant-free and at the same time compatible with Java programming language.

Common Use Cases of Kotlin

Nowadays, Kotlin is widely used in the Android development as the main programming language. Moreover, apart from the sphere of mobile development, Kotlin can be applied in back-end development because of such libraries as Ktor and Spring. Kotlin can also be used for building multiplatform applications due to combining the code of Android, iOS, and web in Kotlin Multiplatform.

Kotlin vs Java: Key Differences

Even though Kotlin and Java have the same virtual machine, there are still some differences between them concerning coding and using the language.

• Syntax Comparison:  The syntax in Kotlin is way shorter than the syntax in Java. Thus, any class that takes 10 lines of code in Java can be written only in one or two lines in Kotlin.
• Performance Comparison:Both programming languages are converted into the bytecode, hence their performance on JVM is almost identical. Kotlin requires a bit more resource when it comes to lambda functions, but the difference is barely noticeable.
• Null Safety: In Java, any variable can be of the null type, hence a lot of null pointer exceptions occur. In Kotlin, the type system differentiates between nullable and non-nullable variables.
• Boilerplate Code:  Constructors, getters, setters and the equals method have to be implemented manually in Java, whereas in Kotlin they are created automatically.
• Coroutines vs Threads:In the case of Java the classical approach to the work with the language presupposes implementation of the thread, which requires a lot of system resources. In case of Kotlin it is possible to implement asynchronous programs like they were synchronous programs with less system resources comparing to threads.
• Extension Functions: Kotlin allows adding additional functions to an existing class without any need for inheritance or any other change in the code. It is impossible in Java, and therefore a developer would need to create utility classes.
• Functional Programming Support:Kotlin makes functions into the first-class citizen and gives a lot of functional programming features that could be used in Kotlin easily. Lambda was introduced to Java in version 8, however it is not a native language feature.

Kotlin vs Java Feature Comparison

• Readability: The reason for easy readability is the clear syntax.
• Security: The security is higher due to the features such as immutability and null safety.
• Memory Management: JVM garbage collector.
• Scalability:The level of development of Java, along with its tools, allows considering it the best programming language for creation of large-scale, durable systems in enterprises, while Kotlin is good for scalable small programs and large-scale Android system.
• Interoperability: Kotlin was created in such a way that it can easily be combined with Java, which means that it will create no problems.

Kotlin vs Java for Android Development

Why Google Recommends Kotlin

Google recommends the use of Kotlin for development of Android apps because it prevents application crashes due to null references and removes all unnecessary repetition and works smoothly with Jetpack and Android Studio. There are some APIs for Android, which are created with Kotlin syntax mainly in mind.

When Java Is Still a Good Choice

Java remains a good choice when developers should maintain legacy Android applications with Java codebases and legacy libraries that were not converted to Kotlin. Enterprise developers often prefer Java programming language because they have expertise in it.

Jetpack and Modern Android Support

Jetpack Compose which is the latest method for creating Android app interfaces provided by Google is built using Kotlin programming language and utilizes many language-specific capabilities. Although technically speaking, some things might be implemented using Java, it doesn't cooperate with many modern solutions and resources any more.

Advantages of Kotlin

• Less Boilerplate Code:The less code is written, the lower chance of making a mistake becomes.
• Better Null Safety:The compiler catches many issues related to null references that would become an issue in production.
• Faster Development:  Short and clear code leads to quick development time.
• Modern Language Features:The coroutines, extension functions and sealed classes provide many advanced language features that are not available in Java.

Advantages of Java

• Large Developer Community:  Having been invented several decades ago, most of the problems have been encountered.
• Mature Ecosystem:  Hundreds of frameworks/libraries are available that have been improved with time.
• Enterprise-Level Stability: Long-term support and backwards compatibility guarantees safety.
• Extensive Library Support: Spring, Hibernate and many others frameworks make Java .

Disadvantages of Kotlin

• Learning Curve: It takes time to get accustomed to Kotlin when switching from Java language despite the ease of learning its basics.
• Compilation Speed: In certain project structures, Kotlin may be compiled slower than the same program written in Java although the difference is not that big anymore due to updates in the compiler.
• Smaller Community: Being a relatively new programming language, Kotlin has a smaller community and fewer libraries compared to Java.

Disadvantages of Java

• Verbose Syntax: The necessity of writing more code than necessary slows down the process.
• Null Pointer Exceptions: Without any null safety feature, these exceptions are the most popular runtime errors.
• More Boilerplate Code:Constructors, getter and setter methods increase the size of simple classes.

Kotlin vs Java Performance Comparison

Runtime Performance

The languages are quite similar in terms of their raw performance as they both are compiled to the same JVM byte-code and thus their execution speed is almost the same for optimized programs.

Compilation Speed

For small projects Java compiles quicker because Kotlin needs additional efforts in the process of compilation to provide its unique features such as null safety or type inference.

Memory Usage

The compactness of Kotlin code can help save some memory in certain cases, although this usually depends on the way the application is developed.

Application Startup Time

Historically, Java applications used to have a slight advantage in this regard; however, Kotlin has significantly reduced this gap due to the evolution of its compiler.

Kotlin vs Java Career Opportunities

Android Development Jobs

Currently, most job offers related to Android development either specifically mention Kotlin or prefer candidates who know it.

Enterprise Software Careers

Java is still in demand in finance, insurance, and other industries where backend programming is required.

Salary and Industry Demand

Kotlin programmers can earn good money because of the demand for mobile application development, while Java programmers have a lot of jobs to choose from.

Popular Companies Using Kotlin

Companies Building Android Apps

Companies including Pinterest, Trello, and Netflix have leveraged Kotlin to develop certain aspects of their Android apps in order to achieve higher stability and efficiency from a programming standpoint.

Companies Using Kotlin for Backend Development

Some popular companies making use of Kotlin are Amazon and Uber, who make use of Kotlin for developing some specific back-end services due to the capability of inter-operation between Java platforms.

Popular Companies Using Java

Enterprise Software Companies

Some popular enterprise software companies using Java for developing enterprise software solutions include IBM and Oracle.

Companies Using Java at Scale

Big companies such as LinkedIn and Google make use of Java for developing back-end services that are robust and capable of dealing with heavy traffic.

Kotlin vs Java Use Cases

• Mobile App Development: Kotlin is used as the main programming language for the development of Android applications whereas some older applications use Java.
• Web Development:Both the programming languages have back-end frameworks and both of them have become popular for the development of Spring Boot applications.
• Backend Development: Both the programming languages can be used for building REST APIs and Microservices.
• Enterprise Applications: Java’s successful history makes this language widely used for development of critical systems.

Kotlin vs Java: Which One Should You Choose?

• For Beginners: Kotlin offers much better syntax which facilitates coding; however, because of the popularity of Java and a lot of tutorials about Java, Java is also a great choice.
• For Android Developers: Without any doubts, Kotlin should be the choice for Android developers because of the official support from Google and further toolchain updates.
• For Enterprise Developers:Stability of the language and its tooling make Java the preferable option for developing enterprise-scale software.
• For Startups: The rapid development cycle in Kotlin makes it suitable for startups with limited staff.
• For Experienced Java Developers: For experienced Java developers learning Kotlin comes naturally due to the inter-operability of both programming languages.

Future of Kotlin and Java

Future of Kotlin

The growth of Kotlin is not restricted by the platform and is expanding to mobile and web apps via Kotlin Multiplatform. JetBrains continues to develop and invest in Kotlin, and its usage in backend applications becomes more popular.

Future of Java

Java is not going away any time soon. The company that owns it regularly updates it with new and modern features, and because of its huge usage in enterprise applications, there is no doubt that it will be popular for many years to come.

Which Language Has Better Long-Term Growth?

Kotlin seems to be growing much faster, especially considering mobile and cross-platform applications, while the growth of Java is much slower since it is very strongly connected to its dominant position in enterprise software.

Conclusion

Both Kotlin and Java are strong programming languages, yet neither of them is going to disappear anytime soon. While, on one hand, Kotlin offers more advanced, safer and cleaner environment and it works great in Android and Agile projects, on the other hand, Java is a programming language with a huge amount of stability, libraries and decades of enterprise projects development experience. Thus, the choice of language depends only on the project.

FAQ’s

1.Is Kotlin better than Java?

Well, it might not always be the case. Everything depends on your particular project. The thing is that Kotlin has cleaner syntax, null safety, and no redundant code which makes it perfect for mobile app development and start-ups. Meanwhile, Java has been working in enterprise environment for decades now, it has lots of libraries and is really stable which is something that many big companies depend on. Well, obviously, Kotlin is the perfect choice for the development of an application for Android, whereas Java is the best fit for enterprise backends.

2. I learn Kotlin or Java first?

If you are going to be an Android developer, then you should start with Kotlin because that is the preferred language by Google and all the tutorials and books use it. In case you just want to be a software engineer, Java can suit you more, as it is widely used now. There are many people who know both these languages due to their interoperability.

3. Is Kotlin faster than Java?

In practical terms, there is little difference in the speed of operation between Kotlin and Java since they generate bytecode which runs on the JVM platform. It’s possible that Kotlin might create some overhead due to its lambdas, but it hardly ever manifests itself. The process of compilation works quicker with Java on smaller projects, and Kotlin's compact code may save memory space in some cases. Overall, the performance of these languages should not influence your choice of language drastically.

4. Can Kotlin replace Java completely?

Kotlin can replace Java in many situations, such as when programming Android applications, however, it will hardly replace Java across the entire software industry anytime soon. The fact is that Java is used heavily by many enterprises and even financial institutions, as well as being involved in large-scale backend systems. Therefore, Java and Kotlin can coexist, since these languages work together. Even so, Kotlin's popularity grows rapidly.

5. Which language has better job prospects, Kotlin or Java?

Currently, there are more vacancies for Java programmers since this programming language can be implemented in many spheres and has existed longer than Kotlin. However, Kotlin programmers are in high demand in the sphere of developing Android because this is an obligatory skill now. People that use these two programming languages will have the broadest choice of vacancies as firms create software using Kotlin but apply Java legacy. Thus, in the future, the demand for Kotlin will be increasing.