Which programming language is used in Android?

Modern Android development primarily relies on Kotlin and Java. While Java has historically been the go-to language since Android’s inception, Kotlin has emerged as Google’s preferred language for writing Android apps. Other languages, like C++ (via the Android NDK) or even cross-platform frameworks, can be used for specific needs. Below is a breakdown of the primary languages and why they matter in Android development.

1. Kotlin: The Current Favorite

Why Kotlin?

• Concise & Expressive: You write less boilerplate code, reducing the likelihood of bugs.
• Interop with Java: Kotlin can seamlessly call Java code and vice versa, making it easy to migrate existing projects.
• Modern Features: Null-safety, coroutines (for concurrency), and extension functions are built right in.

Example (Kotlin):

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val message = "Hello from Kotlin!"
        findViewById<TextView>(R.id.helloTextView).text = message
    }
}

This snippet demonstrates how Kotlin’s streamlined syntax can make Android apps cleaner and more readable.

Official Endorsement

In 2017, Google announced official support for Kotlin, and since then, many Android libraries, documentation, and sample projects have been updated or created with Kotlin in mind.

2. Java: The Classic Choice

Why Java?

• Legacy & Community: Many existing Android codebases and libraries are written in Java.
• Familiarity: Java is one of the most widely taught and used programming languages worldwide.
• Rich Ecosystem: You can leverage a large set of third-party libraries originally designed for Java.

Example (Java):

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        TextView textView = findViewById(R.id.helloTextView);
        textView.setText("Hello from Java!");
    }
}

Though more verbose than Kotlin, Java remains a valid and robust option for Android.

3. C++ (NDK): When Performance Matters

Native Development Kit (NDK)

• Why C++?
  • Used for CPU-intensive tasks (e.g., real-time audio processing, game engines).
  • Gives you lower-level control and potentially better performance in critical sections of your app.
• Considerations
  • Integration complexity: You typically write JNI (Java Native Interface) bindings to bridge C++ with Kotlin/Java.
  • Debugging and memory management can be more complex compared to managed languages.

Example
Portions of a game engine or image processing library might be in C++ for performance, but the UI and the rest of the logic remain in Kotlin or Java.

4. Cross-Platform or Other Options

While Kotlin and Java dominate native Android development, you might also encounter:

• Flutter (Dart): A popular cross-platform toolkit by Google that compiles to native code for both Android and iOS.
• React Native (JavaScript/TypeScript): Uses JavaScript to build apps for multiple platforms.
• Unity (C#): Commonly used for Android/iOS game development.

These frameworks and languages aim to simplify development across devices but still rely on the Android platform’s underlying system for final deployment.

5. Choosing the Right Language for Your Project

1. Kotlin First

   • New Android projects typically start in Kotlin due to Google’s strong backing and its concise syntax.
   • The official Android docs and codelabs highlight best practices in Kotlin.

2. Java for Legacy or Familiarity

   • If you’re maintaining an older codebase or your team is more comfortable with Java, sticking with it is perfectly viable.
   • Many open-source libraries are still in Java, though they often provide Kotlin extensions.

3. C++ or Native Code

   • Stick to specific performance-critical modules (e.g., game loops, low-latency audio, advanced image processing).

4. Cross-Platform Tools

   • If your goal is to deploy on both Android and iOS with one codebase—and you accept the trade-offs—Flutter or React Native can be appealing.

6. Strengthening Your Overall Android Skills

Regardless of which language you choose, solid fundamentals in system design, architecture, and coding best practices are critical for success.

• Enhance your coding fundamentals
  Grokking the Coding Interview: Patterns for Coding Questions
  This course helps you master the algorithms and data structures often tested in technical interviews (relevant for Android dev roles too).

• Understand large-scale mobile architecture
  Grokking System Design Fundamentals
  Learn how mobile apps interact with complex backends and microservices—vital for building scalable Android applications.

Conclusion

For native Android apps, Kotlin is the modern, officially recommended language, while Java remains a trusted staple, especially for legacy or large existing projects. C++ can be used for specialized performance needs, and cross-platform tools (Flutter, React Native) cater to those wanting to ship on multiple platforms with shared code. Ultimately, the best choice depends on project requirements, team expertise, and long-term maintainability. Whether you opt for Kotlin’s concise expressiveness or Java’s familiarity, each language has a valid place in today’s Android ecosystem.