Wifi

You can use the Wi-Fi scanning capabilities provided by the WifiManager API to get a list of Wi-Fi access points that are visible from the device.

Wi-Fi scanning process

There are three steps to the scanning process:

1. Register a broadcast listener for SCAN_RESULTS_AVAILABLE_ACTION, which is called when scan requests are completed, providing their success/failure status. For devices running Android 10 (API level 29) and higher, this broadcast will be sent for any full Wi-Fi scan performed on the device by the platform or other apps. Apps can passively listen to all scan completions on device by using the broadcast without issuing a scan of their own.

2. Request a scan using WifiManager.startScan(). Make sure to check the return status of the method, since the call may fail for any of the following reasons:

   • Scan requests may be throttled because of too many scans in a short time.

   • The device is idle and scanning is disabled.

   • Wi-Fi hardware reports a scan failure.

3. Get scan results using WifiManager.getScanResults(). The returned scan results are the most recently updated results, which may be from a previous scan if your current scan has not completed or succeeded. This means that you might get older scan results if you call this method before receiving a successful SCAN_RESULTS_AVAILABLE_ACTION broadcast.

The following code provides an example of how to implement these steps:

WifiManager wifiManager = (WifiManager)

                   context.getSystemService(Context.WIFI_SERVICE);

BroadcastReceiver wifiScanReceiver = new BroadcastReceiver() {

  @Override

  public void onReceive(Context c, Intent intent) {

    boolean success = intent.getBooleanExtra(

                       WifiManager.EXTRA_RESULTS_UPDATED, false);

    if (success) {

      scanSuccess();

    } else {

      // scan failure handling

      scanFailure();

    }

  }

};

IntentFilter intentFilter = new IntentFilter();

intentFilter.addAction(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION);

context.registerReceiver(wifiScanReceiver, intentFilter);

boolean success = wifiManager.startScan();

if (!success) {

  // scan failure handling

  scanFailure();

}

....

private void scanSuccess() {

  List<ScanResult> results = wifiManager.getScanResults();

  ... use new scan results ...

}

private void scanFailure() {

  // handle failure: new scan did NOT succeed

  // consider using old scan results: these are the OLD results!

  List<ScanResult> results = wifiManager.getScanResults();

  ... potentially use older scan results ...

}

Restrictions

Android 8.0 (API level 26) introduced restrictions regarding permissions and the allowed frequency of Wi-Fi scans.

To improve network performance, security, and battery life, Android 9 (API level 28) tightened permission requirements and further limited the frequency of Wi-Fi scans.