How to block Android wifi packet sniffing

Question

I want to block sniffing to my app and I assume if there is many proxy then a sniffer working in background. But proxylist always 1 proxy.

 ProxySelector defaultProxySelector = ProxySelector.getDefault();
                List<Proxy> proxyList = defaultProxySelector.select(URI.create("http://www.google.com"));
                if (proxyList.size() > 1)
                    Log.d(TAG, "Sniffing");
                else
                    Log.d(TAG, "Safe");

I'm not sure if my opinion is correct also. Is there any other way to block sniffing. Is there a mistake in the line of code.