Async.create().on(Async.io()).next(new Func0<Float>() { // this block is running on a non-main thread, // so you can do some heavey things. Request request = new Request.Builder() .url(url) .build(); Response response = client.newCall(request).execute(); return response.body().string(); }).on(Async.mainThread()).result(new Result<String>() { // this block is running on main thread, // so you can do some UI stuff. @Override public void onResult(String str) { Log.e(TAG, "http response:"+str); } @Override public void onError(Throwable e) { Log.e(TAG, "http execption", e); } }).fire();