Android SDK reference

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Last edited: Jan 27, 2023

Version 4 of the Android SDK replaces users with contexts

A context is a generalized way of referring to the people, services, machines, or other resources that encounter feature flags in your product.

You can upgrade your SDK at any time. However, the ability to target by context, or review context instances that have encountered flags in your application, is only available for customers in the contexts Early Access Program (EAP). If you want access this feature, join the EAP. If you are not part of the EAP, your application can send user contexts to LaunchDarkly and they will appear on the Users list.

Code samples on this page are from the two most recent SDK versions where they differ. To learn more about upgrading, read Android SDK 3.x to 4.0 migration guide.

Overview

This topic documents how to get started with the Android SDK, and links to reference information on all of the supported features.

SDK quick links

LaunchDarkly's SDKs are open source. In addition to this reference guide, we provide source, API reference documentation, and a sample application:

Resource	Location
SDK API documentation	SDK API docs
GitHub repository	android-client-sdk
Sample application	Android
Published module	Maven

SDK version compatibility

The LaunchDarkly Android SDK is compatible with Android SDK versions 21 and higher (Android 5.0, Lollipop).

Getting started

After you complete the Getting started process, follow these instructions to start using the LaunchDarkly SDK in your Android application.

First, declare a dependency on the LaunchDarkly Android SDK:

implementation 'com.launchdarkly:launchdarkly-android-client-sdk:4.0.0'

The SDK uses AndroidX from Jetpack. If your project does not use AndroidX, read Android's migration guide.

Using ProGuard or R8

If you use ProGuard or R8, the aar artifact should automatically include the configuration for the Android SDK. If this is not the case for your build, include the Proguard configuration lines from consumer-proguard-rules.pro into your proguard file.

Next, import the LaunchDarkly client in your application code:

import com.launchdarkly.sdk.*;
import com.launchdarkly.sdk.android.*;

After you install the SDK, create a single, shared instance of LDClient. To create a client instance, you need your environment's mobile key. This authorizes your application to connect to a particular environment within LaunchDarkly. Your mobile key is available in the Projects tab of your Account settings page.

Never embed a server-side SDK key into a client-side application

Mobile keys are not secret and you can expose them in your client-side code without risk. However, never embed a server-side SDK key into a client-side application.

LDClient must be a singleton

It's important to make LDClient a singleton for each LaunchDarkly project. The client instance maintains internal state that allows LaunchDarkly to serve feature flags without making any remote requests. Do not instantiate a new client with every request.

If you have multiple LaunchDarkly projects, you can create one LDClient for each. In this situation, the clients operate independently. For example, they do not share a single connection to LaunchDarkly.

The following example shows the simplest way to create the client. It will block for up to five seconds until the latest feature flags are retrieved from LaunchDarkly.

In the v4 example, the context key is "context-key-123abc". In the v3 example, the user key is "user-key-123abc". Here is how to create the client:

LDConfig ldConfig = new LDConfig.Builder()
    .mobileKey("mobile-key-123abc")
    .build();
LDContext context = LDContext.create("context-key-123abc");
LDClient client = LDClient.init(this.getApplication(), ldConfig, context, 5);

However, calling blocking code from the main thread in an Android app is not a best practice. The preferred method allows you to use the client immediately. The app stores flags from the previous launch on the device and retrieves them for immediate use. The client still connects in the background and continually updates itself with the latest flags.

Making feature flags available to this SDK

You must make feature flags available to mobile SDKs before the SDK can evaluate those flags. If an SDK tries to evaluate a feature flag that is not available, the context will receive the default value for that flag.

To make a flag available to this SDK, check the SDKs using Mobile key checkbox during flag creation, or on the flag's Settings tab. To make all of a project's flags available to this SDK by default, check the SDKs using Mobile key checkbox in your project Settings.

Here is the preferred method:

LDClient client = LDClient.init(this.getApplication(), ldConfig, context, 0);

You can use client to check which variation a particular context will receive for a feature flag.

Here's how:

boolean showFeature = client.boolVariation(flagKey, true);
if (showFeature) {
    // Application code to show the feature
}
else {
    // The code to run if the feature is off
}

Shutting down

Shut down the client when your application terminates. To learn more, read Shutting down.

Data collection

The data collected by the Android SDK persists until the number of cached contexts exceeds a limit. When you call identify, the number of cached contexts increments. Eventually, the number of cached contexts exceeds maxCachedContexts. When that happens, the SDK deletes context data in excess of maxCachedContext, starting with the oldest context first.

Supported features

This SDK supports the following features: