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Feature Flags Java

PostHogOfficialCreated by PostHog

  • Skill
  • Tool integration
  • Data and AI
  • MIT
  • No issues found
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From the author

PostHog feature flags for Java applications
— the description by PostHog

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides guidance and best practices for implementing PostHog feature flags within Java-based applications. It emphasizes server-side evaluation for performance and consistency, while offering strategies for managing flag lifecycles, naming conventions, and minimizing code complexity. The skill also supports the use of PostHog MCP tools for programmatic flag management directly from the development environment.

What it does

  • Provides patterns for integrating PostHog feature flags into Java codebases.
  • Offers best practices for flag naming, targeting, and lifecycle management.
  • Supports server-side flag evaluation to prevent UI flickering.
  • Enables management of feature flags via PostHog MCP tools.
  • Advises on using environment variables for secure configuration.

When to use it

  • When you need to perform canary releases or feature rollouts in a Java application.
  • When you want to decouple feature deployment from code deployment.
  • When you need to manage feature access for specific user segments or groups.
  • When you want to perform A/B testing or experiments on the server side.

Advantages

  • Reduces the risk of deploying new features by allowing instant toggling.
  • Improves application performance through server-side local evaluation.
  • Ensures consistent user experiences by leveraging proper identification and targeting.
  • Simplifies flag maintenance through clear naming and modular implementation patterns.

Usage examples

“How do I check a boolean feature flag in my Java service?”
The agent will provide a code snippet demonstrating how to call the PostHog client to evaluate a boolean flag and execute conditional logic based on the result.
“What are the best practices for naming feature flags?”
The agent will explain the importance of descriptive, type-aware naming conventions like 'is_premium_user' to ensure maintainability and clarity across the team.

Install

  1. Download the skill as a ZIP:

    https://autogineer.com/agent-skills/posthog/feature-flags-java/download

  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip feature-flags-java.zip -d .agents/skills

Documentation by PostHog

PostHog feature flags for Java

This skill helps you add PostHog feature flags to Java applications.

Reference files

  • references/java.md - Java feature flags installation - docs

  • references/adding-feature-flag-code.md - Adding feature flag code - docs

  • references/best-practices.md - Feature flag best practices - docs

Consult the documentation for API details and framework-specific patterns.

Key principles

  • Environment variables: Always use environment variables for PostHog keys. Never hardcode them.

  • Minimal changes: Add feature flag code alongside existing logic. Don't replace or restructure existing code.

  • Boolean flags first: Default to boolean flag checks unless the user specifically asks for multivariate flags.

  • Server-side when possible: Prefer server-side flag evaluation to avoid UI flicker.

PostHog MCP tools

Check if a PostHog MCP server is connected. If available, look for tools related to feature flag management (creating, listing, updating, deleting flags). Use these tools to manage flags directly in PostHog rather than requiring the user to do it manually in the dashboard.

Framework guidelines

No specific framework guidelines.

Files

references/java.md

Java feature flags installation - Docs

The best way to install the PostHog Java SDK is with a build system like Gradle or Maven. This ensures you can easily upgrade to the latest versions.

Look up the latest version of com.posthog.posthog-server.

Gradle

All you need to do is add the posthog-server module to your build.gradle:

build.gradle

PostHog AI

dependencies {
  implementation 'com.posthog:posthog-server:2.+'
}
Maven

All you need to do is add the posthog-server module to your pom.xml:

pom.xml

PostHog AI

<dependency>
  <groupId>com.posthog</groupId>
  <artifactId>posthog-server</artifactId>
  <version>LATEST</version>
</dependency>
Other

See com.posthog.posthog-server in the Maven Central Repository. Clicking on the latest version shows you options for adding dependencies for other build systems.

Setup

Java

PostHog AI

import com.posthog.server.PostHog;
import com.posthog.server.PostHogConfig;
import com.posthog.server.PostHogInterface;
class Sample {
  private static final String POSTHOG_API_KEY = "<ph_project_token>";
  private static final String POSTHOG_HOST = "https://us.i.posthog.com";
  public static void main(String args[]) {
    PostHogConfig config = PostHogConfig
            .builder(POSTHOG_API_KEY)
            .host(POSTHOG_HOST)
            .build();
    PostHogInterface posthog = PostHog.with(config);
    posthog.flush(); // send any remaining events
    posthog.close(); // shut down the client
  }
}

Integrating with Spring

To see how to integrate the PostHog SDK with Spring, check out this sample project.

Debug mode

If you're not seeing the expected events being captured, or the feature flags being evaluated, you can enable debug mode to see what's happening.

To see detailed logging, set the debug configuration option to true.

Java

PostHog AI

PostHogConfig config = PostHogConfig
          .builder(POSTHOG_API_KEY)
          .host(POSTHOG_HOST)
          .debug(true)
          .build();
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Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Needs an MCP server

Security

No issues found by our static scan· No issues found

A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.

Attribution and licence

Created by
PostHog
Publisher
PostHog (Official)
Source
PostHog/skills · skills/posthog/feature-flags/skills/java · commit a5d30e7
Licence
MIT License (redistribution allowed)
  • LICENSE (added by AutoGineer from LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
Synced
Also distributed in
PostHog/skills

AutoGineer is not affiliated with or endorsed by PostHog or PostHog.

Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download feature-flags-java.zip