# OpenFeature SDK for Java

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This is the Java implementation of [OpenFeature](https://openfeature.dev), a vendor-agnostic abstraction library for evaluating feature flags.

We support multiple data types for flags (numbers, strings, booleans, objects) as well as  hooks, which can alter the lifecycle of a flag evaluation.

This library is intended to be used in server-side contexts and has not been evaluated for use in mobile devices.

## Usage

While `Boolean` provides the simplest introduction, we offer a variety of flag types.

```java
import dev.openfeature.javasdk.Structure;

class MyClass {
    public UI booleanExample() {
        // Should we render the redesign? Or the default webpage? 
        if (client.getBooleanValue("redesign_enabled", false)) {
            return render_redesign();
        }
        return render_normal();
    }

    public Template stringExample() {
        // Get the template to load for the custom new homepage
        String template = client.getStringValue("homepage_template", "default-homepage.html");
        return render_template(template);
    }

    public List<HomepageModule> numberExample() {
        // How many modules should we be fetching?
        Integer count = client.getIntegerValue("module-fetch-count", 4);
        return fetch_modules(count);
    }

    public HomepageModule structureExample() {
        Structure obj = client.getObjectValue("hero-module", previouslyDefinedDefaultStructure);
        return HomepageModule.builder()
                .title(obj.getValue("title"))
                .body(obj.getValue("description"))
                .build();
    }
}
```

## Requirements
- Java 8+

## Installation

### Add it to your build

#### Maven
```xml
<dependency>
    <groupId>dev.openfeature</groupId>
    <artifactId>javasdk</artifactId>
    <version>0.1.0</version>
</dependency>
```

If you would like snapshot builds, this is the relevant repository information:

```xml
<repositories>
    <repository>
        <snapshots>
            <enabled>true</enabled>
        </snapshots>
        <id>sonartype</id>
        <name>Sonartype Repository</name>
        <url>https://s01.oss.sonatype.org/content/repositories/snapshots/</url>
    </repository>
</repositories>
```

#### Gradle
```groovy
dependencies {
    implementation 'dev.openfeature:javasdk:0.1.0'
}
```

### Configure it
To configure it, you'll need to add a provider to the global singleton `OpenFeatureAPI`. From there, you can generate a `Client` which is usable by your code. While you'll likely want a provider for your specific backend, we've provided a `NoOpProvider`, which simply returns the default passed in.
```java
class MyApp {
    public void example(){
        OpenFeatureAPI api = OpenFeatureAPI.getInstance();
        api.setProvider(new NoOpProvider());
        Client client = api.getClient();
        // Now use your `client` instance to evaluate some feature flags!
    }
}
```
## Contacting us
We hold regular meetings which you can see [here](https://github.com/open-feature/community/#meetings-and-events).

We are also present on the `#openfeature` channel in the [CNCF slack](https://slack.cncf.io/).

## Contributors

Thanks so much to our contributors.

<a href="https://github.com/open-feature/java-sdk/graphs/contributors">
  <img src="https://contrib.rocks/image?repo=open-feature/java-sdk" alt="Pictures of the folks who have contributed to the project"/>
</a>

Made with [contrib.rocks](https://contrib.rocks).