Android Wi-Fi Scan: Filter printers from ScanResult

Question

I am working on a project, that needs to scan for public Wi-Fi access points.

Currently, I am filtering the ScanResult like this:

for (ScanResult scanResult : wifiList) {
  if (!(scanResult.capabilities.contains("WEP") || 
        scanResult.capabilities.contains("WPA") || 
        scanResult.capabilities.contains("WPA2"))) {

              openWifiList.add(scanResult);    

  }
}

It works fine, except that I also get printers that are nearby.

While scanning, the phone is not connected to any network.

I would have assumed that I get a list that is identically with the list of Wi-Fi connections that is shown in the Wi-Fi Settings on Android. But in the Wi-Fi Setting there is no printer shown ever.

So for 1) I think it is strange that printers show up in the ScanResult list at all, should printers really be visible that way?

---

UPDATE: not all Wi-Fi printers are visible, I got some hints on that, and it seems like the printers that are showing up, do have a special functionality, e.g. HP printers support the HP Wireless Direct functionality (see e.g. https://h30434.www3.hp.com/t5/Inkjet-Printing/Printer-SSID-appearing-on-my-wi-fi-list/td-p/1705073 and https://support.hp.com/rs-en/document/c04577030).

---

And 2) is there any way that I could check whether the ScanResult belongs to a printer?

So far I could only think of filtering for common SSID names, but that will not be very efficient or reliable.

Thanks for any suggestions.

Answer 1

1) Not all printers support the WiFi Direct protocol, HP supports this and also their proprietary protocol you've mentioned (HP Wireless Direct), though your device probably doesn't support it without HP software.

Learn more about connecting to WiFi Direct protocol from Android here.

2) WiFi direct discovery returns String fullDomain, if it contains _ipp - that's most likely a printer.