Kotlin/Java

The Colibri bindings for Kotlin/Java are built using CMake and Gradle. It can be used as AAR (Android Archive) or JAR (Java Archive).

💡 Quick Start: Check out the Example Android App for a complete working implementation!

Usage

Java

Add the dependency to your build.gradle file:

implementation 'com.corpuscore.colibri:colibri-java:0.1.0'

use it like this:

import com.corpuscore.colibri.Colibri;
import com.corpuscore.colibri.ColibriException;

public class Example {
    public static void main(String[] args) {
        // Initialize Colibri (uses default Ethereum Mainnet configuration)
        Colibri colibri = new Colibri();

        try {
            // Call RPC method to get current block number
            byte[] result = colibri.rpc("eth_blockNumber", new Object[]{});
            String blockNumberHex = new String(result);
            System.out.println("Current block number: " + blockNumberHex);
            
            // Example with parameters - get account balance
            byte[] balanceResult = colibri.rpc("eth_getBalance", 
                new Object[]{"0x95222290DD7278Aa3Ddd389Cc1E1d165CC4BAfe5", "latest"});
            String balance = new String(balanceResult);
            System.out.println("Account balance: " + balance);
            
        } catch (ColibriException e) {
            System.err.println("Colibri error: " + e.getMessage());
        } catch (Exception e) {
            System.err.println("Unexpected error: " + e.getMessage());
        }
    }
}

Kotlin

Add the dependency to your build.gradle file:

repositories {
    google()
    mavenCentral()
    // Add the repository where Colibri is published
    maven {
        url = uri("https://your.maven.repo")
    }
}

dependencies {
    implementation("com.corpuscore:colibri-aar:1.0.0")
}

use it like this:

import android.os.Bundle
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.lifecycle.lifecycleScope
import com.corpuscore.colibri.Colibri
import com.corpuscore.colibri.ColibriException
import kotlinx.coroutines.launch

class MainActivity : AppCompatActivity() {
    private lateinit var blockNumberText: TextView
    private lateinit var refreshButton: Button
    private lateinit var statusText: TextView

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

        blockNumberText = findViewById(R.id.blockNumberText)
        refreshButton = findViewById(R.id.refreshButton)
        statusText = findViewById(R.id.statusText)

        // Initialize Colibri (uses default Ethereum Mainnet configuration)
        val colibri = Colibri()

        refreshButton.setOnClickListener {
            lifecycleScope.launch {
                try {
                    statusText.text = "Fetching block number..."
                    refreshButton.isEnabled = false
                    
                    // Call RPC method to get current block number
                    val result = colibri.rpc("eth_blockNumber", arrayOf())
                    val blockNumberHex = String(result)
                    val blockNumber = blockNumberHex.removePrefix("0x").toLong(16)
                    
                    blockNumberText.text = "#$blockNumber"
                    statusText.text = "Updated successfully"
                    
                } catch (e: ColibriException) {
                    statusText.text = "Colibri error: ${e.message}"
                } catch (e: Exception) {
                    statusText.text = "Error: ${e.message}"
                } finally {
                    refreshButton.isEnabled = true
                }
            }
        }
        
        // Fetch block number on startup
        refreshButton.performClick()
    }
}

Example Android App

A complete working example is available in the example directory. This minimal Android app demonstrates:

  • Real-world usage: How to integrate Colibri in an Android application

  • RPC calls: Using eth_blockNumber to fetch the current Ethereum block number

  • Error handling: Proper exception handling for network and Colibri errors

  • Async operations: Using Kotlin coroutines for non-blocking RPC calls

  • UI integration: Updating Android UI components based on RPC results

Running the Example

cd bindings/kotlin/example
./gradlew build
./gradlew installDebug  # Install on connected Android device/emulator

The example app includes:

  • Simple UI with block number display and refresh button

  • Automatic block number fetching on startup

  • Error states and loading indicators

  • Public Ethereum RPC endpoint configuration (no API keys required)

Resources

Building

Make sure you have the Java SDK, Cmake and Swig installed.

JAR

While the CI is building the native libs for multiple platforms, you can build the JAR locally with:

cmake -S . -B build -DGENERATE_JAVA_SOURCES=ON -DCMAKE_BUILD_TYPE=Release -DCURL=false -DKOTLIN=true --build --target c4_java
cd bindings/kotlin
./gradlew -b build-jar.gradle.kts build

AAR

Of course you need to install the Android SDK and NDK first.

cd bindings/kotlin
./gradlew -b build-aar.gradle.kts build
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