Android: Scanning Wifi Network + Selectable list

Question

I\'m trying to creat an application that let you scan the available wifi networks, and then display them in a selectable list. To do that I tried with this code:

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Answer 1

Please try below one. Working well, but not tested properly. Please optimise the code yourself.

public class MainActivity extends Activity {


    WifiManager mainWifi;
    WifiReceiver receiverWifi;

    StringBuilder sb = new StringBuilder();

    private final Handler handler = new Handler();


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        mainWifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);

        receiverWifi = new WifiReceiver();
        registerReceiver(receiverWifi, new IntentFilter(
                WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
        if (mainWifi.isWifiEnabled() == false) {
            mainWifi.setWifiEnabled(true);
        }


        doInback();
    }

    public void doInback() {
        handler.postDelayed(new Runnable() {

            @Override
            public void run() {
                // TODO Auto-generated method stub
                mainWifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);

                if (receiveWifi == null)
                    receiverWifi = new WifiReceiver();
                registerReceiver(receiverWifi, new IntentFilter(
                        WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
                mainWifi.startScan();
                doInback();
            }
        }, 1000);

    }

    public boolean onCreateOptionsMenu(Menu menu) {
        menu.add(0, 0, 0, "Refresh");
        return super.onCreateOptionsMenu(menu);
    }

    public boolean onMenuItemSelected(int featureId, MenuItem item) {
        mainWifi.startScan();

        return super.onMenuItemSelected(featureId, item);
    }


    @Override
    protected void onPause() {
        unregisterReceiver(receiverWifi);
        super.onPause();
    }

    @Override
    protected void onResume() {
        registerReceiver(receiverWifi, new IntentFilter(
                WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
        super.onResume();
    }

    class WifiReceiver extends BroadcastReceiver {
        public void onReceive(Context c, Intent intent) {

            ArrayList<String> connections = new ArrayList<String>();
            ArrayList<Float> Signal_Strenth = new ArrayList<Float>();

            sb = new StringBuilder();
            List<ScanResult> wifiList;
            wifiList = mainWifi.getScanResults();
            for (int i = 0; i < wifiList.size(); i++) {

                connections.add(wifiList.get(i).SSID);
            }


        }
    }


}

Answer 2

Doesn't doInback() create multiple WifiReceivers which then will end up in an Exception as they might not all get unregistered?

Maybe s.th. like this could fix that:

if (receiveWifi==null) {
   receiveWifi = new WifiReceiver();
}