private final BroadcastReceiver wifiScanReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)) {
            wifiList = wifiManager.getScanResults();
            showWifis();
        }
    }
};




public void detectWifi() {
    registerReceiver(wifiScanReceiver, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
    wifiManager.startScan();
}