Signal strength of available access points

See more:

Mobile

Android

I am trying to get the signal strength info from the all the available wifi access points but it doesnt work... Its always returning some null exception it seems. I tried to run it in mobile also but its not working. I have pointed out the line which is creating error by placing a comment in bold.

package a.c;

import java.util.ArrayList; 
import java.util.List;
 
import a.c.WifiActivity.WifiReceiver; 
import android.app.Activity; 
import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.content.IntentFilter; 
import android.net.wifi.ScanResult; 
import android.net.wifi.WifiManager; 
import android.os.Bundle; 
import android.widget.TextView; 
import android.widget.Toast; 
 
public class WifiActivity extends Activity { 
private WifiManager mainWifi; 
private WifiReceiver receiverWifi;
 
TextView sig;
 
/** Called when the activity is first created. */
 
@Override
 
public void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.main); 
mainWifi = (WifiManager) getSystemService(Context.WIFI_SERVICE); 
receiverWifi = new WifiReceiver(); 
registerReceiver(receiverWifi, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)); 
}
 
class WifiReceiver extends BroadcastReceiver { 
public void onReceive(Context c, Intent intent) { 
List wifiList = mainWifi.getScanResults(); 
for (int i = 0; i < wifiList.size(); i++) { 
ScanResult scanResult = wifiList.get(i); 
// I have to put a try catch block here otherwise it returns an exception. 
try{ 
sig.append(scanResult.level+";"); 
} 
catch(exception e){}
}
} 
}
}

Can anyone help me with the code. I dont know what to do to get the signal strength info from the access points.There are access points nearby but im not able get the strength.If anyone could provide the code or any help then i would be thankful. Note: I have added the required permission to access wifistate in the manifest also so its not a problem there.