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Android apps provide a significant boost to businesses, but their success entirely depends on the programming language used to develop the app. Since 2003, Android app development has been dominated by Java. Java was the undefeated king of the programming languages for mobile app development. But in 2017, this dominance of Java was challenged by Kotlin when Google declared Kotlin as the second official language of Android app development. It started a new era in Android app development. 

In this blog, we will find out why people are actively comparing Kotlin, a relatively new challenger to Java which is an experienced champion. Let’s not waste time and get started and see which is better in the Kotlin vs Java bout.

What is Java?

Java is an object-oriented, high-level programming language developed by Sun Microsystems in 1995 and used for developing software for multiple platforms. It is supported by all the platforms like Android, OS X, Linux, and Windows.

Android and most of its apps are developed using Java. It is the most popular and widely-used programming language among developers for developing Android applications. It is also used for numerical computing, desktop computing, and games.

Benefits of Java:

  • Java has a strong coding base, security features and can work on any platform.
  • With the help of code reusability, it becomes easy creating modular applications.
  • Java runs on any platform as it is “write once, runs anywhere” and does not require special software to install it.
  • Java does not use explicit points that help in preventing security threats and risks.
  • It has a multithreaded environment which helps in performing multiple tasks simultaneously. 
  • It is an open-source and large community of professional and experienced developers to help and support the budding developers.

Limitations of Java:

  • Java has a complicated JVM that slows its performance, and it is also more memory-consuming than other native languages. 
  • The biggest drawback of Java is that it has no backup function for the data.
  • Java has a very complex coding structure which reduces the code readability.
  • Java is costly as it has high memory usage.

What is Kotlin?

Kotlin is a general-purpose, cross-platform programming language with type inferences and is used to develop APIs and is easy to write. It runs on Java Virtual Machine and compiles with JavaScript. It was launched in 2016 by JetBrains.

It has 57071 GitHub stars and is the most lovable language among Android app development. It has the support and backing of Google and is used by around 60% of Android developers as it increases productivity, the developer satisfaction rate is high, and provides safety to the code.

Benefits of Kotlin:

  • Kotlin is completely compatible with Java and has high readability. 
  • It compiles with JavaScript and has high interoperability with Java, making it the best choice for cross-platform development.
  • It has fewer crashes, system failures, and bugs due to its compact coding structure.
  • It enhances productivity using various IDEs and is easier to maintain than other programming languages.
  • Kotlin has a faster compiling rate and prevents apps from increasing size.

Limitations of Kotlin:

  • If developers have very little knowledge about Kotlin, switching from Java becomes difficult.
  • Kotlin has a very steep learning code which makes it tricky to understand.
  • It has a small developer community as it is a relatively new language.
  • The initial code readability of Kotlin is very low compared to other languages.

Why are we comparing Kotlin vs Java?

Java has ruled the android app development domain for around 14 years until Kotlin showed up and became a threat to Java’s dominance. The developers started loving Kotlin, and its popularity rose among them for its interoperability with Java. 

With the induction of Kotlin as the official language for Android app development, it underwent massive growth and became the developers’ favorite, and changed the dynamics of the Android app development industry.
The Java vs Kotlin battle got more intense in recent years, as companies and businesses are moving to Kotlin from Java. In 2019, Google announced that it will follow the “Kotlin-first” approach for Android Development.

Kotlin vs Java: Key Differences

Although we have seen that both have their fair share of strengths and weaknesses, it’s still not clear which is better than the other. So let’s follow a different approach and have a closer look at the key differences of both Kotlin and Java.

Null Safety:

In Java, developers find it hard to deal with NullPointerExceptions. It assigns null values to any variables, but when the users access the object reference, Java creates a NullPointerException to the assigned null values. 

There are no NullPointerExceptions in Kotlin as by default all the variable types in Kotlin are non-nullable. If developers try to assign the null value, it will be at compile time.

Smart Casts:

In Java, developers self-check the variable type and then cast it according to the required operation.

In Kotlin, the smart cast function will handle the process of casting checks by using the ‘is-checks’ keyword.

Extension Function:

There is no extension function in Java. If one has to extend the functionality of an existing class, then a new class has to be created to inherit functions from the parent class.

Kotlin provides an extension function to extend the functionality of the existing class without inheriting the parent class. The developers can create extension functions by prefixing the name of the class to the new function using ‘.’ notation.

Function Programming: Lambdas

Before Java8 was released, Java did not have function programming. But still, Java can only use subsets of Java8 features for Android development.

Kotlin is a mixture of functional and object-oriented programming. With the help of methods like high-order functions, lambdas, operator overloading, etc. Kotlin can function in various ways. 

Data Classes:

In Java, for storing data, the developers have to create the variables and other functions like a constructor, getter, setter methods, etc. 

In Kotlin, developers have to declare a class with ‘data’ keywords, and the rest will be auto-generated by the compiler.

Checked Expectations:

Java provides checked expectations that help developers to catch and declare exceptions. It helps them to create robust code with better error handling.

Whereas in Kotlin, there are no checked exceptions, so developers do not have to declare or catch exceptions.

Type Inference:

In Java, each variable type has to be specified explicitly while declaring.

In Kotlin, explicit specification of variable types is unessential. 

Coroutines Support:

By default, Android has a single-thread environment. Java provides multiple threads in the background to operate extensive long-running operations and when these operations are initiated, it becomes hard to manage as the corresponding threads will be blocked.

Kotlin also provides multiple threads for operating extensive long-operations, but the coroutines support of Kotlin helps in suspending the execution at a certain amount of time without blocking the threads.

Kotlin vs Java: Which is better?

As it is known, both Java and Kotlin compile to bytecode and run on Java Virtual Machine, which helps developers to use both programming languages in the same project. But the main advantage Kotlin has over Java in android development is its ability to use the latest version of the programming language.

Even though Android has integrated with JVM, Java developers cannot use Java 16 for android development as JVM is consistent with only Java 7 or 8. JetBrains very skillfully overcame this limitation by allowing the developers to use Kotlin’s latest version with ease. 

Android developers can use top-grade features of newly released Kotlin updates as there is no problem with Kotlin when JVM is used with an integrated compiler. This core advantage gives Kotlin an edge over Java and makes it better than Java. JetBrains considered all drawbacks of Java and created Kotlin. JetBrains has worked hard to make Kotlin’s code more elegant and concise as compared to Java.


Based on the above Kotlin vs Java comparison for android development, we can conclude that Kotlin is better than Java mainly due to

  • Concise code syntax
  • High performance
  • MultiPlatform feature as it helps developers to use a single code for multiple platforms.

Java is still one of the top-performing languages in the backend as it bypasses JVM’s limitations and performs at its full potential. It has one of the largest developer communities and uncountable tools to support budding developers. Kotlin has a brighter future, and it might challenge Java in the backend too, but we have to wait for it to happen. 

If you have any doubts or queries about android app development, you can feel free to contact us anytime you like. We are here to help you.

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Nirmalsinh Rathod
Nirmalsinh Rathod

Director - Mobile Technologies

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