title: NullPointerException after disabling Wifi state and trying to enable again
body: <p>The first time I enable Wifi and then disable it everything is fine, but if I try to re-enable the Wifi after (either immediately or waiting for mobile data to connect again) it throws a NullPointerException and Force Closes.</p>
  
  <pre><code>private void toggleWifi(){
  
      if (wifi == 0){
          wifiManager.setWifiEnabled(true);
          scanOnly = wifiManager.createWifiLock(WifiManager.WIFI_MODE_SCAN_ONLY, "scanOnly");
          scanOnly.acquire();
  
          bWifi.setText("Turn Wifi OFF");
  
          List&lt;ScanResult&gt; wifiResults = wifiManager.getScanResults();
  
          StringBuilder sb = new StringBuilder("Scan Results:\n");            
          sb.append("-----------------------\n");
  
          for (ScanResult r : wifiResults) {
              sb.append(r.SSID + " " + r.level + " dBM\n");
          }
  
          tvWifi.setText(sb.toString());
  
          wifi = 1;
  
      } else {
          scanOnly.release();
          wifiManager.setWifiEnabled(false);
  
          bWifi.setText("Turn WiFi ON");
  
          tvWifi.setText("");
  
          wifi = 0;
      }
  
  }
  </code></pre>
  
  <p>The error is on this line:</p>
  
  <pre><code>for (ScanResult r : wifiResults) {
      sb.append(r.SSID + " " + r.level + " dBM\n");
  }
  </code></pre>