Step by Step Guide to Building a Linear API Integration in Java

Introduction

Hey there, fellow developer! Ready to supercharge your project management workflow? Let's dive into building a Linear API integration in Java. Linear's API is a powerhouse for automating tasks, syncing data, and creating custom workflows. By the end of this guide, you'll have a robust integration that'll make your team wonder how they ever lived without it.

Prerequisites

Before we jump in, make sure you've got:

• A Java development environment (I know you've got this covered!)
• A Linear account and API key (grab one from your account settings)
• Your favorite HTTP client library (we'll use OkHttp in this guide, but feel free to use what you're comfortable with)

Setting up the project

First things first, let's get our project set up:

1. Create a new Java project in your IDE of choice.
2. Add the necessary dependencies to your pom.xml or build.gradle:

<dependency>
    <groupId>com.squareup.okhttp3</groupId>
    <artifactId>okhttp</artifactId>
    <version>4.10.0</version>
</dependency>

Authentication

Now, let's tackle authentication:

public class LinearApiClient {
    private static final String API_KEY = "your_api_key_here";
    private static final String BASE_URL = "https://api.linear.app/graphql";
    private final OkHttpClient client;

    public LinearApiClient() {
        this.client = new OkHttpClient.Builder()
            .addInterceptor(chain -> {
                Request original = chain.request();
                Request request = original.newBuilder()
                    .header("Authorization", API_KEY)
                    .build();
                return chain.proceed(request);
            })
            .build();
    }
}

Pro tip: In a real-world scenario, you'd want to store that API key securely, not hardcode it. But you knew that already, right?

Making API requests

Linear uses GraphQL, so our requests will be a bit different from typical REST APIs. Here's how to make a basic request:

public String makeRequest(String query) throws IOException {
    RequestBody body = RequestBody.create(query, MediaType.get("application/json; charset=utf-8"));
    Request request = new Request.Builder()
        .url(BASE_URL)
        .post(body)
        .build();

    try (Response response = client.newCall(request).execute()) {
        return response.body().string();
    }
}

Core functionality implementation

Let's implement some core features:

Fetching issues

public List<Issue> getIssues() throws IOException {
    String query = "{ issues { nodes { id title description } } }";
    String response = makeRequest(query);
    // Parse JSON response and return List<Issue>
}

Creating new issues

public Issue createIssue(String title, String description) throws IOException {
    String query = String.format(
        "mutation { issueCreate(input: { title: \"%s\", description: \"%s\" }) { issue { id title description } } }",
        title, description
    );
    String response = makeRequest(query);
    // Parse JSON response and return Issue
}

You get the idea - updating and deleting issues follow a similar pattern.

Advanced features

Want to take it up a notch? Here are some advanced features to consider:

• Implement pagination for large result sets
• Add filtering and sorting options to your queries
• Set up webhooks to receive real-time updates

Error handling and logging

Don't forget to implement robust error handling and logging. Your future self will thank you when debugging:

try {
    // API call here
} catch (IOException e) {
    logger.error("API call failed", e);
    throw new LinearApiException("Failed to communicate with Linear API", e);
}

Testing the integration

You're a pro, so I don't need to tell you about the importance of testing. But here's a gentle reminder to write both unit tests for your methods and integration tests to ensure everything plays nice with the actual API.

Best practices and optimization

To keep your integration running smoothly:

• Respect rate limits (Linear's pretty generous, but still)
• Implement caching for frequently accessed data
• Use connection pooling in your HTTP client for better performance

Conclusion

And there you have it! You've just built a solid Linear API integration in Java. From here, the sky's the limit. You could expand this to create a full-fledged Linear client library, or integrate it into your existing project management tools.

Remember, the best integrations are those that solve real problems for your team. So go forth and automate, integrate, and innovate!

Happy coding!