The programming language that you choose for your Android app development can significantly impact the success of your project in the long run. The right programming language can enhance productivity, improve code quality, and ultimately lead to a better user experience. 

With countless options available, developers often find themselves at a crossroads, wondering which path to take. Among the options available, two programming languages stand out as the most popular contenders: Kotlin and Java.

But which one is better for Android app development from Kotlin and Java? Why is Kotlin among the best alternatives for Java? Why is Kotlin preferred over Java?

Here, we will compare Kotlin vs Java for Android development and know their respective advantages, performance characteristics, learning curves, and much more. It will help you get a clear understanding of which language aligns well with your mobile app development goals. 

Kotlin for Android App Development

Kotlin is a statically typed, modern, and highly expressive programming language that has gained significant popularity in the Android development community. Google officially endorsed it as a first-class language for Android app development in 2017.

Kotlin Vs Java

Kotlin is designed to be concise, which means you can achieve the same functionality with less code compared to Java. Its expressive syntax makes code more readable and less prone to errors.

Why Use Kotlin for Android Development?

Android app development with Kotlin offers several benefits, including:

  1. Interoperability with Java – Kotlin is fully interoperable with Java, meaning you can seamlessly use Kotlin and Java code within the same Android project. This makes it easy for developers to transition from Java to Kotlin gradually.
  1. Modern Language Features – Kotlin includes modern language features such as lambdas, extension functions, data classes, and smart casts, which simplify Android app development and enhance code quality.
  1. Official Android Support  – Kotlin is officially supported by Android Studio (the primary IDE for Android development), which means it’s easy to set up and use for Android projects.
  1. Community and Libraries – Kotlin has a growing and active community of developers, and it benefits from a wide range of libraries and tools that enhance Android app development.
  1. Performance  – Kotlin’s performance is on par with Java, and in some cases, it can even outperform Java due to its more concise nature.
  1. Android KTX – Kotlin Android Extensions (Android KTX) is a set of Kotlin extensions that simplifies Android code, making it more idiomatic and concise.
  1. Conciseness – Kotlin’s concise syntax allows developers to write less code, reducing boilerplate and making code more readable.
  1. Null Safety  – Kotlin for Android development includes built-in null safety features, reducing the risk of null pointer exceptions, a common source of crashes in Android apps.
  1. Smart Casts – Kotlin’s smart casts simplify type casting, reducing the need for explicit type checks and casts.
  1. Data Classes – Kotlin provides data classes that automatically generate common methods like equals(), hashCode(), and toString(), streamlining the creation of model classes.
  1. Lambdas – Language Kotlin supports concise lambda expressions, making working with higher-order functions and asynchronous programming easier.
  1. Coroutines – Kotlin offers native support for coroutines, simplifying asynchronous programming and improving code readability.

Read More: Top Rated Kotlin Development Company.

Java for Android Development

Android primarily uses Java as its primary programming language. Here are some key aspects of Java for Android development:

Java was the original and official language for Android app development. It is a mature programming language that has a well-established ecosystem for development scenarios of different kinds, like web development, software development, game development, and more. 

Developers can find extensive libraries, frameworks, and tools to use Java for Android app development. 

Kotlin vs Java Features for Android App Development

Now, let’s compare the features of both languages to understand why Kotlin is better than Java when it comes to Android development:

ConcisenessConcise syntax reduces boilerplate code.More verbose syntax requires more code.
Null SafetyBuilt-in null safety reduces null pointer exceptions.Null safety relies on manual checks.
Extension FunctionsSupports extension functions for existing classes.Lacks extension functions.
Smart CastsOffers smart casts for safer type casting.Requires explicit type checks and casts.
Data ClassesProvides data classes for automatic code generation.Manual creation of model classes.
LambdasSupports concise lambda expressions.Lambda expressions are available.
CoroutinesOffers native support for coroutines.No native coroutine support (prior to Java 14).
Ecosystem and LibrariesGrowing ecosystem with Kotlin-specific libraries.Mature ecosystem with extensive libraries.
Wide AdoptionAdoption is increasing at a fast pace because of the benefits it offers. Was the primary language for Android app development.
PerformanceFaster performance than Java.Good performance with bytecode optimization.
Community SupportActive community with resources and support.Large and active Java developer community.
Cross-PlatformCan be used for cross-platform development.Limited cross-platform support (via NDK).

Kotlin vs Java Performance

Among the most popular alternatives to Java, Kotlin offers several performance benefits. It is worth noting that both languages use the concept of bytecode compilation on Java Virtual Machine (JVM), meaning the performance characteristics are pretty similar.

However, there are some features in Kotlin that enhance the overall performance of Android apps when compared to Java.

For instance, the null safety features in Kotlin decrease the quantity of runtime exceptions, which aids in faster performance. Another aspect is the immutability of data structures in Kotlin, which is another reason for better performance. 

Below is a comparison of Java vs Kotlin performance to help you understand things better:

Performance AspectJavaKotlin
Code SizeCode size can be slightly larger in Java due to verbosity.Kotlin’s concise syntax leads to smaller code sizes. 
It loads faster, especially on slower devices or networks.
Null Safety ImpactJava allows null references, which can lead to null pointer exceptions at runtime.Kotlin’s null safety features reduce null pointer exceptions, improving app stability.
ConcurrencyJava uses traditional multithreading, which can be error-prone.Kotlin’s coroutines simplify asynchronous programming and lead to more efficient and responsive apps.
InteroperabilityFull interoperability with Java allows seamless use of Java libraries and code.Full interoperability with Java ensures access to the rich ecosystem of Java libraries and tools.
Garbage CollectionBoth languages rely on the Android runtime’s garbage collection, which can impact app performance.Performance considerations related to garbage collection are similar for both languages.
Startup TimeSimilar startup times as both languages run on the Android runtime.Kotlin’s smaller code size leads to slightly faster startup times.
Compilation SpeedJava tends to have faster compilation times.Kotlin compilation times can be slightly slower due to additional language features.
Runtime PerformanceComparable performance in terms of execution speed and efficiency.Comparable performance as both compile to bytecode for the Android runtime.

So, when it comes to raw runtime performance, there is usually no significant difference between Java and Kotlin for Android app development. Other factors such as code readability, maintainability, and developer productivity are often more important considerations when choosing between the two languages. 

Kotlin’s concise syntax and null safety features indirectly bring faster performance by improving code size and reducing the likelihood of runtime crashes.

Kotlin vs Java Learning Curve

  • Kotlin Learning Curve:

Kotlin is known for its relatively gentle learning curve, especially for developers who are already familiar with Java. It was designed to be easy to pick up for Java developers.

If you already have experience with Java, you’ll find many concepts in Kotlin to be familiar, and you can often leverage your existing Java knowledge.

Kotlin’s concise syntax and modern features make code more readable, which facilitates the learning process.

  • Java Learning Curve

Java is a well-established language with a steeper learning curve for newcomers, primarily due to its more verbose syntax and boilerplate code.

Developers who are new to Java may need more time to become proficient in the language and its idiosyncrasies.

Java’s strict type system and explicit declarations require a deeper understanding of object-oriented programming (OOP) concepts.

Kotlin Community and Ecosystem

  • The Kotlin community has been rapidly growing and is considered vibrant and enthusiastic. 
  • Kotlin has a dedicated website ( with extensive documentation, tutorials, and a blog, making it a valuable resource for developers.
  • Forums and social media platforms like Stack Overflow, Reddit, and GitHub have active Kotlin communities where developers can seek help, share knowledge, and collaborate.
  • There are Kotlin user groups and meetups in various cities, providing opportunities for in-person networking and learning.
  • The availability of Android-specific libraries and tools for Kotlin has expanded significantly, and Kotlin has become a first-class language in the Android ecosystem.

Java Community and Ecosystem

  • Java has one of the largest and most established developer communities in the world, with a deep and enduring history in Android development.
  • There is an abundance of resources, tutorials, forums, and documentation available for Java, making it easy for developers to find solutions to their problems and stay updated on best practices.
  • The broader Java community extends beyond Android development and encompasses a wide range of domains and platforms, contributing to the language’s longevity and vitality.
  • Android Studio, the primary Integrated Development Environment (IDE) for Android development, provides excellent support for Java, including code generation, refactoring tools, and a visual layout editor.

Libraries and Tools Available for Kotlin

  • Kotlin enjoys growing support from third-party libraries and tools specifically designed for Android development. Many popular Android libraries now offer Kotlin-friendly versions, and new libraries are often Kotlin-first or Kotlin-exclusive.
  • Kotlin’s interoperability with Java ensures that developers can leverage the extensive Java libraries and tools available in the Android ecosystem seamlessly.
  • Android KTX (Kotlin Extensions) is a set of Kotlin-specific extensions for Android that simplifies Android development by providing idiomatic Kotlin APIs.

Libraries and Tools Available for Java

  • Java has an extensive library ecosystem that has been built over decades, covering a wide range of domains, including Android development.
  • Android developers have access to a vast array of third-party libraries, frameworks, and tools that can be used with Java. Many of these libraries have been used successfully in countless Android projects.
  • Android Studio and the Android Gradle build system provide excellent support for integrating Java libraries into Android projects, simplifying the process of adding external dependencies.

Interoperability Between Java and Kotlin in Android Development

Java and Kotlin are designed to work seamlessly together, allowing developers to write code in either language within the same Android project. This interoperability is a key feature and provides numerous benefits for transitioning between the two languages.

  • Mixed Language Source Code: In an Android project, you can have both Kotlin and Java source files. They can reference and call each other without any issues.
  • Java Libraries: Kotlin can directly use Java libraries, and vice versa. This means you can take advantage of the extensive Java library ecosystem in Kotlin projects and utilize Kotlin in existing Java projects.
  • Null Safety: Kotlin’s null safety features extend to Java code, helping prevent null pointer exceptions when Kotlin code interacts with Java code that doesn’t have null annotations.
  • Data Conversion: Kotlin provides tools for seamless data conversion between nullable and non-nullable types when interacting with Java.
  • Gradual Transition: Interoperability makes it easier to transition from Java to Kotlin or vice versa in a gradual manner. You can start by writing new code in the desired language while keeping existing code intact.
  • Leverage Existing Code: For projects with an existing codebase in Java, you can leverage Kotlin’s concise syntax, null safety, and modern features in new code, improving code quality without rewriting everything.
  • Easier Adoption: Developers familiar with Java can gradually learn Kotlin without abandoning their Java skills. Kotlin’s interoperability ensures that Java expertise remains valuable.
  • Access to Rich Ecosystems: Both languages can access each other’s ecosystems. Kotlin projects can benefit from the extensive Java library ecosystem, while Java projects can use Kotlin’s modern features and extensions.
  • Improved Code Quality: Kotlin’s null safety and modern language features can lead to better code quality and fewer runtime errors, making your Android app more robust.
best kotlin projects

For the benefits Kotlin offers, a large number of Android apps built on Java have migrated to Kotlin over the years. Some parts or codebases of these apps might still be running in Java because of the interoperability, but Kotlin is the primary language used now.


Trello, a popular project management app, announced in 2019 that they had fully migrated their Android app from Java to Kotlin. They reported improved developer productivity and code readability as key benefits.


Pinterest is another notable app that embraced Kotlin for Android development. They started incorporating Kotlin into their Android app in 2017 and continued to do so as it gained popularity.


Evernote, a widely used note-taking app, adopted Kotlin in 2017. They cited reasons such as concise code and enhanced safety features as motivations for the transition.


While not a complete migration, Uber’s Android app started including Kotlin years back. They found Kotlin to be a valuable addition to their codebase, improving their development process.


Slack, a popular communication and collaboration app, started doing its Android app development with Kotlin in 2018. They mentioned that Kotlin’s null safety features were particularly beneficial in reducing crashes.


Coursera, the online learning platform, began incorporating Kotlin into their Android app in 2017. They found that Kotlin helped streamline their code and improve development efficiency.

Basecamp 3

Basecamp, a project management and team collaboration app, adopted Kotlin for its Android app development. They reported positive experiences with the language in terms of developer productivity.


AliExpress, the e-commerce platform, migrated part of its Android app to Kotlin. They noted that Kotlin’s concise syntax and null safety features were advantageous.

  • Kotlin-First Approach 

Some prominent companies and startups have adopted a Kotlin-first approach, meaning they use Kotlin as the primary language for Android app development. This trend reflects the confidence in Kotlin’s modern features, developer-friendly syntax, and improved safety.

  • Java Legacy

Java continues to be widely used in Android app development, particularly in apps with established codebases. 

  • Coexistence

Interoperability between Kotlin and Java allows developers to use both languages within the same project. This coexistence is especially prevalent in apps undergoing a transition from Java to Kotlin.

  • Google’s Kotlin Focus

Google has continued to promote Kotlin as the language of choice for Android development. Many official Android libraries and resources now have Kotlin support, reinforcing Kotlin’s position in the ecosystem.

employee time tracking

Why is Kotlin Preferred Over Java? Final Verdict

Kotlin’s adoption in the Android development community has been on a steady rise since Google officially endorsed it as a first-class language for Android. 

Many new Android projects are now being started in Kotlin, and existing apps are gradually migrating to Kotlin.

Kotlin continues its growth and will eventually become the dominant language for Android development. Its modern features, null safety, and enhanced developer experience make it an attractive choice.

Java will persist in Android development for the foreseeable future due to the vast number of existing Java-based apps and libraries. Many developers will continue to maintain and update Java codebases.

Interoperability between Kotlin and Java will remain essential as many projects continue to use both languages. The ability to incrementally adopt Kotlin or integrate Kotlin features into existing Java code will continue to be valuable.

Both Google and JetBrains (the creators of Kotlin) will likely invest in further enhancing tooling support for Kotlin, making it even more attractive for developers.

Frequently Asked Questions 

Why is Kotlin better than Java for Android development?

Kotlin offers extra features than Java that allows android app developers to create unique solutions. Kotlin makes it easier for the developers to work with multiple-threaded applications. 

Is Kotlin the best for Android app development?

Kotlin is better than Java for android app development. It offers the users the ease of development and integrating cross app functionalities easily. Most developers prefer kotlin for the features it offers to create unique android applications. 

Is Kotlin used more than Java for Android?

As discussed, Kotlin is an advanced framework and much popular than Java among android developers. Around 87% of the apps in USA Google Play are built using Kotlin. 

Why did Google choose Kotlin over Java?

With Kotling writing codes is cleaner. It was introduced as an improvement of Java and with time due to its features and simpler coding it gained popularity. 

Why should you switch to Kotlin from Java?

One significant point is, Kotlin is compatible with Java and thus can let android developers build applications faster in lesser time. Kotlin offers multiple advantages over Java and let developers build a strong presence in the market. 

Managing Director

Arun Goyal is a passionate technology enthusiast and a seasoned writer with a deep understanding of the ever-evolving world of tech. With years of experience in the tech industry, Arun has established himself as a prominent figure in the field, sharing his expertise and insights through his engaging and informative blog posts.

Octal In The News

Octal IT Solution Has Been Featured By Reputed Publishers Globally

Let’s build something great together!

Connect with us and discover new possibilities.

    Gain More With Your Field Service

    We’re always keeping our finger on the pulse of the industry. Browse our resources and learn more.

    Let's schedule a call
    Mobile App Development Mobile App Development