Observable.just(responseBody)
.subscribeOn(
Schedulers.io())
.subscribe(new Observer<ResponseBody>() {
@Override public void onSubscribe(Disposable d) {}
@Override public void onNext(ResponseBody responseBody) {
createFileApk(responseBody, apkFile);}
@Override public void onError(Throwable e) {
showErrorDownloading(e);}
@Override public void onComplete() {}
});