Is there a way to refactor this RxJava code?

I have my Observable subscription that looks like:

      compositeDisposables.add(githubService.getRepos()
                    .subscribeOn(Schedulers.io())
                    .observeOn(AndroidSchedulers.mainThread())
                    .subscribe(
                            (List<GithubRepo> value) -> {
                                if (!value.isEmpty()) {
                                    ArrayAdapter<GithubRepo> adapter = new 
     ArrayAdapter<GithubRepo>
                                            (MainActivity.this,

     android.R.layout.simple_spinner_dropdown_item, value);
                                    reposSpinner.setAdapter(adapter);
                                    reposSpinner.setEnabled(true);
                                } else {
                                    showEmptyRepoAdapterState();
                                }
                            },
                            (Throwable e) -> {
                                e.printStackTrace();
                                Toast.makeText(this, "Cannot load repositories", Toast
                                        .LENGTH_SHORT).show();
                            }));

Is there a way to abstract all the code in the subscribe() method to a separate method? I've tried doing this:

private DisposableSingleObserver<List<GithubRepo>> getRepos(){
    return (List<GithubRepo> value) -> {
        if (!value.isEmpty()) {
            ArrayAdapter<GithubRepo> adapter = new ArrayAdapter<GithubRepo>
                    (MainActivity.this,
                            android.R.layout.simple_spinner_dropdown_item, value);
            reposSpinner.setAdapter(adapter);
            reposSpinner.setEnabled(true);
        } else {
            showEmptyRepoAdapterState();
        }
    },
    (Throwable e) -> {
        e.printStackTrace();
        Toast.makeText(this, "Cannot load repositories", Toast
                .LENGTH_SHORT).show();
    };
};

But I get an error: Target type of a lambda conversion must be an interface.

So, is there a way to refactor this code?? How do I even know the expected return value?

I figured it out. The method signature that I used required two Consumer parameters so the huge block of code I had could be refactored to this:

  compositeDisposables.add(githubService.getRepos()
                    .subscribeOn(Schedulers.io())
                    .observeOn(AndroidSchedulers.mainThread())
                    .subscribe(
                            successResponse(),
                            errorResponse()
                    ));

And then the parameters looked like:

    private Consumer<List<GithubRepo>> successResponse() {
    return (List<GithubRepo> value) -> {
        if (!value.isEmpty()) {
            ArrayAdapter<GithubRepo> adapter = new ArrayAdapter<GithubRepo>
                    (MainActivity.this,
                            android.R.layout.simple_spinner_dropdown_item, value);
            reposSpinner.setAdapter(adapter);
            reposSpinner.setEnabled(true);
        } else {
            showEmptyRepoAdapterState();
        }
    };
}

And

     private Consumer<Throwable> errorResponse() {
    return (Throwable e) -> {
        e.printStackTrace();
        Toast.makeText(this, "Cannot load repositories", Toast
                .LENGTH_SHORT).show();
    };
}