JAVA SDK usage

Install dependencies

The first thing we will do is install the Open Feature SDK and the GO Feature Flag provider.

maven

<dependency>
    <groupId>dev.openfeature</groupId>
    <artifactId>sdk</artifactId>
    <artifactId>1.12.2</artifactId>
</dependency>
<dependency>
    <groupId>dev.openfeature.contrib.providers</groupId>
    <artifactId>go-feature-flag</artifactId>
    <version>0.4.0</version>
</dependency>

gradle

implementation group: 'dev.openfeature', name: 'javasdk', version: '1.12.2'
implementation group: 'dev.openfeature.contrib.providers', name: 'go-feature-flag', version: '0.4.0'

Initialize your Open Feature client

To evaluate the flag you need to have an Open Feature configured in your app. This code block shows you how you can create a client that you can use in your application.

java

import dev.openfeature.contrib.providers.gofeatureflag.GoFeatureFlagProvider;
import dev.openfeature.contrib.providers.gofeatureflag.GoFeatureFlagProviderOptions;
import dev.openfeature.sdk.EvaluationContext;
import dev.openfeature.sdk.MutableContext;
import dev.openfeature.sdk.OpenFeatureAPI;

// ...

GoFeatureFlagProviderOptions options = GoFeatureFlagProviderOptions.builder().endpoint("http://localhost:1031/").build();
GoFeatureFlagProvider provider = new GoFeatureFlagProvider(options);

OpenFeatureAPI.getInstance().setProvider(provider);
OpenFeatureAPI api = OpenFeatureAPI.getInstance();
Client featureFlagClient = api.getClient();

Kotlin

import dev.openfeature.contrib.providers.gofeatureflag.GoFeatureFlagProvider
import dev.openfeature.contrib.providers.gofeatureflag.GoFeatureFlagProviderOptions
import dev.openfeature.sdk.EvaluationContext
import dev.openfeature.sdk.MutableContext
import dev.openfeature.sdk.OpenFeatureAPI

// ...

val options = GoFeatureFlagProviderOptions.builder().endpoint("http://localhost:1031/").build()
val provider = GoFeatureFlagProvider(options)

OpenFeatureAPI.getInstance().provider = provider
// wait for the provider to be ready
val api = OpenFeatureAPI.getInstance()
val featureFlagClient = api.client

Evaluate your flag

This code block explain how you can create an EvaluationContext and use it to evaluate your flag.

note

In this example we are evaluating a boolean flag, but other types are available.

Refer to the Open Feature documentation to know more about it.

java

// Context of your flag evaluation.
// With GO Feature Flag you MUST have a targetingKey that is a unique identifier of the user.
EvaluationContext userContext = new MutableContext("1d1b9238-2591-4a47-94cf-d2bc080892f1")
  .add("firstname", "john")
  .add("lastname", "doe")
  .add("email","john.doe@gofeatureflag.org")
  .add("admin", true)
  .add("anonymous", false);

Boolean adminFlag = featureFlagClient.getBooleanValue("flag-only-for-admin", false, userContext);
if (adminFlag) {
    // flag "flag-only-for-admin" is true for the user
} else {
    // flag "flag-only-for-admin" is false for the user
}

Kotlin

// Context of your flag evaluation.
// With GO Feature Flag you MUST have a targetingKey that is a unique identifier of the user.
val userContext: EvaluationContext = MutableContext("1d1b9238-2591-4a47-94cf-d2bc080892f1")
  .add("firstname", "john")
  .add("lastname", "doe")
  .add("email", "john.doe@gofeatureflag.org")
  .add("admin", true)
  .add("anonymous", false)

val adminFlag = featureFlagClient.getBooleanValue("bool_targeting_match", false, userContext)
if (adminFlag) {
    // flag "flag-only-for-admin" is true for the user
} else {
    // flag "flag-only-for-admin" is false for the user
}

Contribute to the provider

You can find the source of the provider in the open-feature/java-sdk-contrib repository.