When it comes to mobile app development, Kotlin and Java are the two most widely used programming languages by Android app development companies. Both languages are fully supported by Google and have their unique advantages and disadvantages.
That being said, let’s uncover the secrets of Kotlin and Java, and try to understand which programming language is best for your Android app development project in 2025.
What is Java?
Java is an object-oriented programming language primarily used in the back-end development of web applications. While launched in 1995 by Sun Microsystems for interactive television, it has now secured a notable place in Android application development. In fact, Java is ranked in the top three most popular programming languages used by Android app development companies worldwide. Some popular apps built using Java include Spotify, Cash App, Twitter, and LinkedIn.
Pros of using Java for Android app development:
- Simple learning curve
- Multithreading support
- Extensive community
- Secure and robust
Cons of using Java for Android app development:
- Complex syntax
- Large APK files
- More coding
You may also like reading: 10 Best Frameworks For Hybrid App Development
What is Kotlin?
When JetBrains came up with Kotlin in 2011, no one was sure that it would later become an official Android language. Today, Kotlin is used to develop a wide range of applications, including mobile apps, web apps, and server-side apps. Over 5.8 million developers worldwide count on it, around 60% of professional Android developers. Some popular apps built using Kotlin include Netflix, Airbnb, Tinder, and Pinterest.
Pros of using Kotlin for Android app development:
- Concise coding
- Interoperability
- Streamlined tooling
- Robust safety
Cons of using Kotlin for Android app development:
- Slow compilation speed
- Unavailability of resources
- Complex learning curve
You may also like digging into: Top Ruby on Rails Outsourcing Companies.
What are the Differences Between Java and Kotlin?
While Kotlin focuses on a more concise syntax, Java is all about a more mature ecosystem with extensive libraries. Below, we have compiled a list of some major differentiating points between Kotlin and Java:
1. Null Safety
Java’s NullPointerExceptions can be frustrating when an object reference is assigned a null value. This may require Android app development companies to handle the issue before continuing their work. Kotlin doesn’t let you assign null values to variables or objects. Thereby, you will see no NullPointerExceptions in Kotlin.
2. Extension Functions
Java relies on extensive work to modify existing methods. Whereas, Kotlin uses extension functions that make modifying classes efficient and fast. This opens an array of possibilities during Android development. Furthermore, Kotlin has a simpler coding structure due to its concise nature.
3. Smart Casting
Java requires explicit type checks and casting, so you will need to constantly monitor the type of variable during operations. On the other hand, Kotlin comes with smart casts that can automatically handle type checks. When coding in Kotlin, rest assured knowing your variables are automatically cast through its intelligent compiler.
4. Type Interface
While Java relies on explicit type declarations, Kotlin features type interference. This feature allows Kotlin developers to omit type annotations and reduce boilerplate code. Whereas, Java app development companies need to explicitly declare the type of variable they’re creating. This gives them more control over how their codes can be interpreted.
5. Widening Conversions
A widening conversion helps you change a value to a data type. This allows for any possible value of the original data. Java enables automatic widening, which means smaller types can be automatically converted to bigger ones. On the other hand, Kotlin requires an explicit conversion process every time you want to convert from small to large numbers.
| Features | Java | Kotlin |
|---|---|---|
| Extension Functions | Not available | Available |
| Null Safety | Includes NullPointerExceptions | Non-nullable available |
| String Templates | Available, but it doesn’t support expressions | Two different types of string literals available and support expressions |
| Wildcard-types | Available | Unavailable, but has declaration-site variance and type projections |
| Smart Casts | Unavailable | Available to track conditions inside of the expression |
| Lazy Keyword | Not available | Available |
| Language Scripting | Not available | Available |
How to Decide Between Java and Kotlin for Android Development?
After you understand the pros and cons of Java and Kotlin, it’s time to choose the right programming language for your next Android project. Here are a few important factors to keep in mind:
1. Project Scope and Size
First things first, make sure you understand the requirements and scope of your Android development project. For instance, rapid development projects demand the capabilities of Kotlin. Whereas, long-term projects with established timelines might go well with Java. However, Kotlin is preferred for its concise syntax, increased productivity, and seamless interoperability with existing Java code.
2. Development Speed and Features
When it comes to development speed, Kotlin is praised for its conciseness and reduced boilerplate code. It offers several modern language features like type inference, lambda expressions, and extension functions that can make code easier to read. On top of that, Kotlin is fully interoperable with Java if you are planning to migrate your codebase from Java to Kotlin.
3. Use Cases
Both programming languages provide tremendous versatility to develop high-quality mobile apps. However, they have some specific use cases. For example, Java is a general choice for a wide range of projects, including standalone applications and backend applications. On the other hand, Kotlin has taken center stage as a preferred language among Android developers. It is also ideal for cross-platform application development.
4. Team Skill Set
Don’t forget to evaluate your team’s strength and familiarity with programming. Are they fluent in adapting to Kotlin’s features? Then Kotlin might be a better choice over Java. However, if they are still profound in Java, it is better to rely on Java to avoid errors and delays. So, be sure to gather input from your development team before making any decision.
5. Community and Ecosystem
It’s true that Java has been around for a long time; thus, it has a massive community and ecosystem. In other words, you’ll find extensive libraries, frameworks, and resources for Java development companies. Whereas, Kotlin’s ecosystem and community are still growing and are not as extensive as Java’s.
6. Future Maintenance
If you are foreseeing new integration and continual updates, it is ideal to opt for Kotlin development. This is because its features continue to evolve and range from concise readable code and reduced complexities to the adaptability of modern languages with improved code quality.
The Final Verdict
So which one is better – Java or Kotlin? While Kotlin will be the better choice in most modern cases, Java still has its uses in some legacy systems and enterprise-level applications. The decision ultimately comes to you project scope, team expertise, and long-term maintenance strategy. Still not sure? Consider getting in touch with a leading Android development company today!
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