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Flagsmith Android/Kotlin SDK

This SDK can be used for Android applications written in Kotlin. The source code for the client is available on Github.

Installation

Gradle - App

In your project path app/build.gradle add a new dependence

//flagsmith
implementation 'com.github.Flagsmith:flagsmith-kotlin-android-client:1.0.1'

You should be able to find the latest version in the releases section of the GitHub repository.

Gradle - Project

In the new Gradle version 7+ update your settings.gradle file to include JitPack if you haven't already

repositories {
google()
mavenCentral()

maven { url "https://jitpack.io" }
}

Basic Usage

The SDK is initialised against a single environment within a project on https://flagsmith.com, for example the Development or Production environment. You can find your Client-side Environment Key in the Environment settings page.

Initialization

Within your Activity inside onCreate()

lateinit var flagsmith : Flagsmith

override fun onCreate(savedInstanceState: Bundle?) {
initFlagsmith();
}

private fun initFlagsmith() {
flagsmith = Flagsmith(environmentKey = FlagsmithConfigHelper.environmentDevelopmentKey, context = context)
}

Custom configuration

The Flagsmith SDK has various parameters for initialisation. Most of these are optional, and allow you to configure the Flagsmith SDK to your specific needs:

  • environmentKey Take this API key from the Flagsmith dashboard and pass here
  • baseUrl By default we'll connect to the Flagsmith backend, but if you self-host you can configure here
  • context The current Context is required to use the Flagsmith Analytics functionality
  • enableAnalytics Enable analytics - default true. Disable this if you'd like to avoid the use of Context
  • analyticsFlushPeriod The period in seconds between attempts by the Flagsmith SDK to push analytic events to the server
  • enableRealtimeUpdates Enable the SDK to receive updates to features in real time while the app is running
  • defaultFlags Provide default flags the the SDK to ensure values are availble when no network connection can be made
  • cacheConfig Disabled by default, but when enabled will allow Flagsmith to fall back to cached values when no network connection can be made
  • request / read / writeTimeoutSeconds Fine-grained control of the HTTP timeouts used inside the Flagsmith SDK

Flags

Now you are all set to retrieve feature flags from your project. To list and print all flags:

flagsmith.getFeatureFlags { result ->
result.fold(
onSuccess = { flagList ->
Log.i("Flagsmith", "Current flags:")
flagList.forEach { Log.i("Flagsmith", "- ${it.feature.name} - enabled: ${it.enabled} value: ${it.featureStateValue ?: "not set"}") }
},
onFailure = { err ->
Log.e("Flagsmith", "Error getting feature flags", err)
})
}

Get Flag Object by featureId

To retrieve a feature flag boolean value by its name:

flagsmith.hasFeatureFlag(forFeatureId = "test_feature1") { result ->
val isEnabled = result.getOrDefault(true)
Log.i("Flagsmith", "test_feature1 is enabled? $isEnabled")
}

Create a Trait for a user identity

flagsmith.setTrait(Trait(key = "set-from-client", value = "12345"), identity = "test@test.com") { result ->
result.fold(
onSuccess = { _ ->
Log.i("Flagsmith", "Successfully set trait")

},
onFailure = { err ->
Log.e("Flagsmith", "Error setting trait", err)
})
}

Get all Traits

To retrieve a trait for a particular identity as explained here Traits

flagsmith.getTraits(identity = "test@test.com") { result ->
result.fold(
onSuccess = { traits ->
traits.forEach {
Log.i("Flagsmith", "Trait - ${it.key} : ${it.value}")
}
},
onFailure = { err ->
Log.e("Flagsmith", "Error setting trait", err)
})
}

Providing Default Flags

You can define default flag values when initialising the SDK. This ensures that your application works as intended in the event that it cannot receive a response from our API.

val defaultFlags = listOf(
Flag(
feature = Feature(
id = 345345L,
name = "Flag 1",
createdDate = "2023‐07‐07T09:07:16Z",
description = "Flag 1 description",
type = "CONFIG",
defaultEnabled = true,
initialValue = "true"
), enabled = true, featureStateValue = "value1"
),
Flag(
feature = Feature(
id = 34345L,
name = "Flag 2",
createdDate = "2023‐07‐07T09:07:16Z",
description = "Flag 2 description",
type = "CONFIG",
defaultEnabled = true,
initialValue = "true"
), enabled = true, featureStateValue = "value2"
),
)

// Then pass these during initialisation:
flagsmith = Flagsmith(
environmentKey = FlagsmithConfigHelper environmentDevelopmentKey,
defaultFlags = defaultFlags,
context = context)

Cache

By default, the cache is off. When turned on, Flagsmith will cache all flags returned by the API (to permanent storage), and in case of a failed response, fall back on the cached values. The cache can be turned off or on during initialisation:

flagsmith = Flagsmith(
environmentKey = FlagsmithConfigHelper environmentDevelopmentKey,
cacheConfig = FlagsmithCacheConfig(enableCache = true)
context = context)

You can also set a TTL for the cache (in seconds) for finer control:

FlagsmithCacheConfig (
enableCache = true,
cacheTTLSeconds = 3600L, // 1 hour
val cacheSize = 1024L * 1024L, // 1 MB
)

Override the default base URL

By default, the client uses a default configuration. You can override the configuration as follows. If you're also using realtime flag updates in your hosted environment you'll also need to pass the eventSourceUrl in a similar fashion:

        flagsmith = Flagsmith(
environmentKey = Helper.environmentDevelopmentKey,
context = context,
baseUrl = "https://hostedflagsmith.company.com/"),
eventSourceUrl = "https://api.hostedflagsmith.company.com/"