public interface GitHubService {
  @GET("/users/{user}/repos")
  List<Repo> listRepos(@Path("user") String user);
}

RestAdapter restAdapter = new RestAdapter.Builder()
      .setEndpoint("https://api.github.com")
      .build();

GitHubService service = restAdapter.create(GitHubService.class);

List<Repo> repos = service.listRepos("octocat");