NoClassDefFoundError for DefaultConnectingIOReactor when using Unirest with RapidAPI in Android

Other Questions RapidAPI
1

I’m working on an Android app that needs to connect to the Spoonacular API through RapidAPI. I’m using Unirest for HTTP requests but keep running into a class resolution error.

Here’s my gradle configuration:

apply plugin: 'com.android.application'

android {
    // other config
    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'
}

My code for making the API call:

HttpResponse<JsonNode> apiResponse = null;
try {
    apiResponse = Unirest.get("https://spoonacular-recipe-food-nutrition-v1.p.mashape.com/recipes/findByIngredients?ingredients=chicken%2Crice&number=10&ranking=2")
            .header("X-Mashape-Key", "my-api-key")
            .header("X-Mashape-Host", "spoonacular-recipe-food-nutrition-v1.p.mashape.com")
            .asJson();
} catch (UnirestException ex) {
    ex.printStackTrace();
}

The error I get is:

java.lang.NoClassDefFoundError: Failed resolution of: Lorg/apache/http/impl/nio/reactor/DefaultConnectingIOReactor;
    at com.mashape.unirest.http.options.Options.refresh(Options.java:85)
    at com.mashape.unirest.http.options.Options.<clinit>(Options.java:46)

What am I missing in my setup? Any suggestions on how to resolve this dependency issue would be great.

2

This happens because Unirest depends on Apache HttpAsyncClient, which requires NIO reactor classes that Android’s stripped-down Apache HTTP library doesn’t include. Even with the legacy library enabled, Android misses the async/NIO components where DefaultConnectingIOReactor is found. I encountered this same issue with another RapidAPI service previously. The simplest solution is to replace Unirest with another HTTP client; OkHttp is a great choice for RapidAPI calls and is well-supported on Android. You can change your Unirest call to use OkHttp like this: OkHttpClient client = new OkHttpClient(); Request request = new Request.Builder().url("https://spoonacular-recipe-food-nutrition-v1.p.mashape.com/recipes/findByIngredients?ingredients=chicken%2Crice&number=10&ranking=2").addHeader("X-Mashape-Key", "my-api-key").addHeader("X-Mashape-Host", "spoonacular-recipe-food-nutrition-v1.p.mashape.com").build();. This eliminates dependency conflicts and OkHttp adequately manages JSON responses without significant additional code.

3

yeah, this is a pain with unirest on android. the nio reactor classes dont exist in apaches android libs. just drop unirest and use volley or retrofit instead - theyll work better and you wont deal with these dependency headaches.

4

Same issue here. Unirest uses HttpAsyncClient internally, which needs the full Apache HTTP stack. Android only gives you a subset through its legacy library. You might think adding httpasyncclient as a dependency fixes it, but that usually creates more conflicts because of version mismatches with Android’s bundled stuff. I switched to Retrofit with Gson converter instead. Works perfectly with RapidAPI endpoints and the setup’s way cleaner. Just create a service interface with @GET and @Header parameters, then run it through the Retrofit client. Way more reliable than dealing with Apache’s dependency mess on Android.