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Quickstart

The Eppo Android SDK enables feature flags and experiments in your Android applications with just a few lines of code. It handles flag evaluation and experiment assignments locally on the device, making it fast and reliable for your users.

The SDK handles all the complexity of feature flag evaluation and experiment assignment locally in your application, with no network calls required after initial setup. This guide will walk you through installing the SDK and implementing your first feature flag and experiment.

Installation​

Add the Eppo SDK to your Android project by including it in your app's build.gradle file:

dependencies {
    implementation 'cloud.eppo:android-sdk:4.4.0'
}

Feature Flags​

Feature flags are a way to toggle features on and off without needing to deploy code.

Initialize the SDK​

First, initialize the SDK with your API key. You'll need to do this early in your application lifecycle, typically in your Application subclass:

import cloud.eppo.android.EppoClient;

public class MyApplication extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        
        // Initialize the SDK
        try {
            EppoClient eppoClient = new EppoClient.Builder("YOUR_SDK_KEY", this)
                .buildAndInit();
        } catch (Exception e) {
            // Handle initialization error
            Log.e("Eppo", "Failed to initialize SDK", e);
        }
    }
}
tip

Get your SDK key from the Eppo web interface.

Feature Flags​

Once initialized, you can start using feature flags anywhere in your app:

import cloud.eppo.android.EppoClient;

// Get the SDK instance
EppoClient eppoClient = EppoClient.getInstance();

// Check if a feature should be enabled
String userId = getCurrentUserId(); // Your user identification logic
Map<String, Object> attributes = new HashMap<>();
attributes.put("userType", "premium");
attributes.put("country", "US");

boolean isEnabled = eppoClient.getBooleanAssignment(
    "new-feature", // Feature flag key
    userId,        // Subject/user identifier
    attributes,    // Optional targeting attributes
    false          // Default value if flag is not found
);

if (isEnabled) {
    // Show new feature
    showNewFeature();
} else {
    // Show existing feature
    showExistingFeature();
}

Running Experiments​

To run experiments, you'll need to add a logging callback during initialization to track assignments:

import cloud.eppo.android.EppoClient;
import cloud.eppo.android.dto.Assignment;

public class MyApplication extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        
        // Create assignment logger
        AssignmentLogger logger = new AssignmentLogger() {
            @Override
            public void logAssignment(Assignment assignment) {
                // Log assignment to your analytics system
                analytics.track("Eppo Experiment Assignment",
                    new Properties()
                        .putValue("experiment", assignment.getExperiment())
                        .putValue("variation", assignment.getVariation())
                        .putValue("subject", assignment.getSubject())
                );
            }
        };

        // Initialize with logger
        EppoClient eppoClient = new EppoClient.Builder("YOUR_SDK_KEY", this)
            .assignmentLogger(logger)
            .buildAndInit();
    }
}

Then use the SDK to make experiment assignments:

String variation = eppoClient.getStringAssignment(
    "recommendation-algo",    // Experiment key
    userId,                   // Subject identifier
    attributes,              // Targeting attributes
    "control"                // Default variation
);

switch (variation) {
    case "variant-a":
        showRecommendationAlgoA();
        break;
    case "variant-b":
        showRecommendationAlgoB();
        break;
    default:
        showDefaultRecommendations();
}

Assignment Types​

The SDK provides different methods based on your flag/experiment value type:

// Boolean flags/experiments
boolean value = eppoClient.getBooleanAssignment(key, subject, attributes, false);

// Numeric values
int intValue = eppoClient.getIntegerAssignment(key, subject, attributes, 0);
double doubleValue = eppoClient.getDoubleAssignment(key, subject, attributes, 0.0);

// String values
String stringValue = eppoClient.getStringAssignment(key, subject, attributes, "default");

// JSON configuration
JSONObject config = eppoClient.getJSONAssignment(key, subject, attributes, defaultJson);

Next Steps​

Now that you have the basics working, here are some advanced topics to explore: