AccountManager wrapper with an easier API and RxJava support

BetterAccountManager.java

/**
 * Wrapper for {@link AccountManager} with improved functionality and RxJava support.
 * 
 * Originally found from <a href="https://github.com/novoda/spikes/tree/master/gertherb/android/src/main/java/com/gertherb/authentication">github.com/spikes/gertherb</a>,
 * and modified to work with a newer RxJava version, using {@link Single} instead of {@link rx.Observable}.
 *
 * @author Ataul Munim
 * @author Santeri Elo
 */
public class BetterAccountManager {
    private final AccountManager accountManager;
    private final Activity activity;

    @Inject public BetterAccountManager(Activity activity) {
        this.activity = activity;
        this.accountManager = AccountManager.get(activity.getApplicationContext());
    }

    /**
     * Starts the login flow and gets the new user's access token.
     *
     * @param options {@link Bundle} may be empty or null (not that important)
     * @return Single emitting a {@link Token}
     */
    public Single<Token> addAccountAndGetToken(final Bundle options) {
        return addAccount(options)
                .flatMap(s -> getSessionKey(options))
                .compose(applySchedulers());
    }

    /**
     * Gets the current user's access token. If no user is logged in, normal login flow is started.
     *
     * @param options {@link Bundle} may be empty or null (not that important)
     * @return Single emitting a {@link Token}
     */
    public Single<Token> getSessionKeyOrAddAccount(Bundle options) {
        return getSessionKey(options)
                .onErrorResumeNext(addNewAccount(options))
                .compose(applySchedulers());
    }

    private Single<Token> getSessionKey(final Bundle options) {
        return Single.create(new Single.OnSubscribe<Token>() {
            @Override
            public void call(SingleSubscriber<? super Token> subscriber) {
                Account[] accounts = accountManager.getAccountsByType(ACCOUNT_TYPE);
                if (accounts.length == 0) {
                    subscriber.onError(new NoAccountException());
                    return;
                }

                Bundle result;
                try {
                    result = getAuthToken(accounts[0], options);
                } catch (AuthenticatorException | OperationCanceledException | IOException e) {
                    subscriber.onError(e);
                    return;
                }

                subscriber.onSuccess(new Token(accounts[0].name, result.getString(AccountManager.KEY_AUTHTOKEN)));
            }
        });
    }

    private Bundle getAuthToken(Account account, Bundle options) throws AuthenticatorException, OperationCanceledException, IOException {
        return accountManager.getAuthToken(account, AUTHTOKEN_TYPE, options, activity, null, null).getResult();
    }

    private Func1<Throwable, Single<? extends Token>> addNewAccount(final Bundle options) {
        return onErrorThrowable -> {
            if (onErrorThrowable.getCause() instanceof NoAccountException) {
                return addAccountAndGetToken(options);
            }
            return Single.error(onErrorThrowable.getCause());
        };
    }

    private Single<String> addAccount(final Bundle options) {
        return Single.create(new Single.OnSubscribe<String>() {
            @Override
            public void call(SingleSubscriber<? super String> subscriber) {
                Bundle result;
                try {
                    result = accountManager.addAccount(ACCOUNT_TYPE, AUTHTOKEN_TYPE, null, options, activity, null, null).getResult();
                } catch (OperationCanceledException | AuthenticatorException | IOException e) {
                    subscriber.onError(e);
                    return;
                }

                subscriber.onSuccess(result.getString(AccountManager.KEY_ACCOUNT_NAME));
            }
        });
    }

    private <T> Single.Transformer<T, T> applySchedulers() {
        return observable -> observable.subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread());
    }
}

This gist is for RxJava v1?

This gist is for RxJava v1?

Yes, but I don't see why this couldn't be adapted for RxJava2+ with small changes.