NoClassDefFoundError for DefaultConnectingIOReactor when using Unirest with Android for API integration

[josephk]

I’m working on an Android app and trying to connect to a food recipe API using the Unirest library. I’ve followed the instructions for setting up Unirest without Maven, and I’ve added the jar file to my project.

Here’s my gradle configuration:

apply plugin: 'com.android.application'

android {
    useLibrary 'org.apache.http.legacy'
    
    packagingOptions {
        exclude 'META-INF/DEPENDENCIES'
        exclude 'META-INF/LICENSE'
        exclude 'META-INF/NOTICE'
        exclude 'META-INF/ASL2.0'
    }
}

dependencies {
    implementation 'com.rapidapi:rapidconnect-android:0.1'
    implementation files('libs/unirest-java-1.4.9.jar')
    implementation 'org.json:json:20171018'
    implementation('org.apache.httpcomponents:httpmime:4.3.6') {
        exclude module: 'httpclient'
    }
    implementation 'org.apache.httpcomponents:httpclient-android:4.3.5'
}

And here’s my API call code:

HttpResponse<JsonNode> apiResponse = null;
try {
    apiResponse = Unirest.get("https://recipe-api.example.com/search?query=chicken,rice&limit=10")
            .header("X-API-Key", "my_api_key")
            .header("X-API-Host", "recipe-api.example.com")
            .asJson();
} catch (UnirestException ex) {
    ex.printStackTrace();
}

However, I’m encountering a crash when the app attempts to make the request. The error indicates that the DefaultConnectingIOReactor class cannot be found. Has anyone experienced this before? What could I be missing in my configuration?

[amelial]

Check your proguard rules - they might be stripping out reactor classes during build. I had the same crash and fixed it by adding -keep class org.apache.http.nio.** to proguard-rules.pro. Also, unirest’s tricky with newer Android versions. I’d switch to okhttp or retrofit - they play much better with Android.

[Finn_Mystery]

Had the same issue with Unirest in an Android project. That NoClassDefFoundError means you’re missing dependencies for async HTTP requests. Add these to your gradle file: implementation 'org.apache.httpcomponents:httpasyncclient:4.1.3' and implementation 'org.apache.httpcomponents:httpcore-nio:4.4.10'. Unirest needs these for async stuff to work. Clean and rebuild after adding them.

[alexlee]

This happens because Unirest needs HttpAsyncClient components that aren’t in the main jar. I hit the same issue migrating an old Android project. DefaultConnectingIOReactor is part of the NIO components for non-blocking I/O operations. Besides adding the missing dependencies others mentioned, you might need to explicitly include httpcore:4.4.10 since version conflicts pop up. Also check if you’re running this on the main thread - Android blocks async operations there. Try wrapping your API call in an AsyncTask or use a background thread. Your legacy HTTP library declaration should help, but packaging options sometimes mess with class loading.