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Yegor Bugayenko
14 May 2014

Object-Oriented GitHub API

GitHub is an awesome platform for maintaining Git sources and tracking project issues. I moved all my projects (both private and public) to GitHub about three years ago and have no regrets. Moreover, GitHub gives access to almost all of its features through RESTful JSON API.

There are a few Java SDK-s that wrap and expose the API. I tried to use them, but faced a number of issues:

Keeping in mind all those drawbacks, I created my own library—jcabi-github. Let's look at its most important advantages.

Object Oriented for Real

GitHub server is an object. A collection of issues is an object, an individual issue is an object, its author is an author, etc. For example, to retrieve the name of the author we use:

GitHub github = new RtGitHub(/* credentials */);
Repos repos = github.repos();
Repo repo = repos.get(new Coordinates.Simple("jcabi/jcabi-github"));
Issues issues = github.issues();
Issue issue = issues.get(123);
User author = new Issue.Smart(issue).author();

Needless to say, GitHub, Repos, Repo, Issues, Issue, and User are interfaces. Classes that implement them are not visible in the library.

Mock Engine

MkGitHub class is a mock version of a GitHub server. It behaves almost exactly the same as a real server and is the perfect instrument for unit testing. For example, say that you're testing a method that is supposed to post a new issue to GitHub and add a message into it. Here is how the unit test would look:

public class FooTest {
  public void createsIssueAndPostsMessage() {
    GitHub github = new MkGitHub("jeff");
      Json.createObjectBuilder().add("name", owner).build()
    new Foo().doTheThing(github);

This is much more convenient and compact than traditional mocking via Mockito or a similar framework.


It is based on JSR-353 and uses jcabi-http for HTTP request processing. This combination makes it highly customizable and extensible, when some GitHub feature is not covered by the library (and there are many of them).

For example, you want to get the value of hireable attribute of a User. Class User.Smart doesn't have a method for it. So, here is how you would get it:

User user = // get it somewhere
// name() method exists in User.Smart, let's use it
System.out.println(new User.Smart(user).name());
// there is no hireable() method there

We're using method json() that returns an instance of JsonObject from JSR-353 (part of Java7).

No other library allows such direct access to JSON objects returned by the GitHub server.

Let's see another example. Say, you want to use some feature from GitHub that is not covered by the API. You get a Request object from GitHub interface and directly access the HTTP entry point of the server:

GitHub github = new RtGitHub(oauthKey);
int found = github.entry()

jcabi-http HTTP client is used by jcabi-github.


All classes are truly immutable and annotated with @Immutable. This may sound like a minor benefit, but it was very important for me. I'm using this annotation in all my projects to ensure my classes are truly immutable.

Version 0.8

A few days ago we released the latest version 0.8. It is a major release, that included over 1200 commits. It covers the entire GitHub API and is supposed to be very stable. The library ships as a JAR dependency in Maven Central (get its latest versions in Maven Central):