Как сканировать доступный WI-FI на KITKAT?

Question

Я создаю приложение, которое сканирует доступные сети WI-FI и затем показывает их в списке.вот мой код:

public class MainActivity extends ListActivity {

WifiManager mainWifiObj;
WifiScanReceiver wifiReciever;
ListView list;
String wifis[];

EditText pass;


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


    list=getListView();

    mainWifiObj = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
    wifiReciever = new WifiScanReceiver();
    mainWifiObj.startScan();


    list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {


            String ssid = ((TextView) view).getText().toString();
            connectToWifi(ssid);
            Toast.makeText(MainActivity.this,"Wifi SSID : "+ssid,Toast.LENGTH_SHORT).show();

        }
    });
}

protected void onPause() {
    unregisterReceiver(wifiReciever);
    super.onPause();
}

protected void onResume() {
    registerReceiver(wifiReciever, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
    super.onResume();
}
class WifiScanReceiver extends BroadcastReceiver {
    @SuppressLint("UseValueOf")
    public void onReceive(Context c, Intent intent) {
        List<ScanResult> wifiScanList = mainWifiObj.getScanResults();
        wifis = new String[wifiScanList.size()];
        for(int i = 0; i < wifiScanList.size(); i++){
            wifis[i] = ((wifiScanList.get(i)).toString());
        }
        String filtered[] = new String[wifiScanList.size()];
        int counter = 0;
        for (String eachWifi : wifis) {
            String[] temp = eachWifi.split(",");

            filtered[counter] = temp[0].substring(5).trim();//+"\n" + temp[2].substring(12).trim()+"\n" +temp[3].substring(6).trim();//0->SSID, 2->Key Management 3-> Strength

            counter++;

        }
        list.setAdapter(new ArrayAdapter<String>(getApplicationContext(),R.layout.list_item,R.id.label, filtered));


    }
}

private void finallyConnect(String networkPass, String networkSSID) {
    WifiConfiguration wifiConfig = new WifiConfiguration();
    wifiConfig.SSID = String.format("\"%s\"", networkSSID);
    wifiConfig.preSharedKey = String.format("\"%s\"", networkPass);


    int netId = mainWifiObj.addNetwork(wifiConfig);
    mainWifiObj.disconnect();
    mainWifiObj.enableNetwork(netId, true);
    mainWifiObj.reconnect();

    WifiConfiguration conf = new WifiConfiguration();
    conf.SSID = "\"\"" + networkSSID + "\"\"";
    conf.preSharedKey = "\"" + networkPass + "\"";
    mainWifiObj.addNetwork(conf);
}

private void connectToWifi(final String wifiSSID) {
    final Dialog dialog = new Dialog(this);
    dialog.setContentView(R.layout.connect);
    dialog.setTitle("Connect to Network");
    TextView textSSID = (TextView) dialog.findViewById(R.id.textSSID1);

    Button dialogButton = (Button) dialog.findViewById(R.id.okButton);
    pass = (EditText) dialog.findViewById(R.id.textPassword);
    textSSID.setText(wifiSSID);


    dialogButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String checkPassword = pass.getText().toString();
            finallyConnect(checkPassword, wifiSSID);
            dialog.dismiss();
        }
    });
    dialog.show();
}
}

Но во время выполнения на андроид версии Lollipop работает отлично и все.Но на андроид версии KITKAT вылетает и говорит (К сожалению, «Имя приложения» остановилось.).Это происходит при сканировании сетей WI-FI.Я не знаю, что я делаю не так.

Вот мой logcat на андроид KITKAT:

Process: com.example.app, PID: 14212
java.lang.RuntimeException: Error receiving broadcast Intent { act=android.net.wifi.SCAN_RESULTS flg=0x4000010 } in com..app.MainActivity$WifiScanReceiver@424b88a0
    at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:773)
    at android.os.Handler.handleCallback(Handler.java:733)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:146)
    at android.app.ActivityThread.main(ActivityThread.java:5756)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
    at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.StringIndexOutOfBoundsException: length=0; index=5
    at java.lang.String.indexAndLength(String.java:584)
    at java.lang.String.substring(String.java:1449)
    at com.example.app.MainActivity$WifiScanReceiver.onReceive(MainActivity.java:83)
    at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:763)
    at android.os.Handler.handleCallback(Handler.java:733) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:146) 
    at android.app.ActivityThread.main(ActivityThread.java:5756) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 
    at dalvik.system.NativeStart.main(Native Method)