Scanning WIFI in Android

Question

I checked my device Wifi is enabled and once enabled, I tried scan all available Wifi networks. But can't detect any Wifi network. My program is

      protected void onCreate(Bundle savedInstanceState) {
            String service1 = Context.WIFI_SERVICE;
            wifi = (WifiManager)getSystemService(service1);
            if(!wifi.isWifiEnabled())
                wifi.setWifiEnabled(true);

            receiverWifi = new WifiReceiver();
            registerReceiver(receiverWifi, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
            wifi.startScan();   //startScan 
            displayWifiNetworks();
      }

     class WifiReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            // TODO Auto-generated method stub
            Toast.makeText(SDcard_DetailView.this, "in onReceive ...", Toast.LENGTH_LONG).show();
            wifiList = wifi.getScanResults();
            for(int i = 0; i< wifiList.size(); i++) {
                System.out.println(wifiList.get(i).toString());
            }

        }   
    }


    public void displayWifiNetworks() {
        //Toast.makeText(this, "displaying WiFi information...", Toast.LENGTH_LONG).show(); 
        //if(null != wifi.getScanResults().get(1).SSID)     
        if(wifiList.size() > 0)
            Toast.makeText(this, "Networks available!", Toast.LENGTH_LONG).show();


    }

Receiver manifest file

        <!-- in order to access the WifiManage.getScanResults()  -->
        <receiver 
           android:name="com.example.connectivitymanager.MainActivity$WifiReceiver">
           <intent-filter>
              <action android:name="android.net.wifi.STATE_CHANGE"></action>
              <action android:name="android.net.wifi.SCAN_RESULTS"></action>
           </intent-filter>
       </receiver>

I also have permission as

    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
    <uses-permission android:name="android.permission.WAKE_LOCK"/>

Thanks

Answer 1

Do you have the below line?

<uses-permission android:name="android.permission.INTERNET"/>

It's possible that you can't access WIFI because you're not even allowed to access the internet!

Answer 2

    package wf1.wf2.wf3;    
import java.util.ArrayList;
import java.util.HashMap;    
import java.util.List;    
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.WifiConfiguration;   
import android.net.wifi.WifiManager;    
import android.os.Bundle;    
import android.util.Log;   
import android.view.View;    
import android.view.View.OnClickListener;    
import android.widget.AdapterView;    
import android.widget.Button;    
import android.widget.ListView;    
import android.widget.SimpleAdapter;    
import android.widget.TextView;    
import android.widget.Toast;

public class WiFiDemo extends Activity implements OnClickListener
 {      
    WifiManager wifi;       
    ListView lv;
    TextView textStatus;
    Button buttonScan;
    int size = 0;
    List<ScanResult> results;

    String ITEM_KEY = "key";
    ArrayList<HashMap<String, String>> arraylist = new ArrayList<HashMap<String, String>>();
    SimpleAdapter adapter;

    /* Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        textStatus = (TextView) findViewById(R.id.textStatus);
        buttonScan = (Button) findViewById(R.id.buttonScan);
        buttonScan.setOnClickListener(this);
        lv = (ListView)findViewById(R.id.list);

        wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
        if (wifi.isWifiEnabled() == false)
        {
            Toast.makeText(getApplicationContext(), "wifi is disabled..making it enabled", Toast.LENGTH_LONG).show();
            wifi.setWifiEnabled(true);
        }   
        this.adapter = new SimpleAdapter(WiFiDemo.this, arraylist, R.layout.row, new String[] { ITEM_KEY }, new int[] { R.id.list_value });
        lv.setAdapter(this.adapter);

        registerReceiver(new BroadcastReceiver()
        {
            @Override
            public void onReceive(Context c, Intent intent) 
            {
               results = wifi.getScanResults();
               size = results.size();
            }
        }, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));                    
    }

    public void onClick(View view) 
    {
        arraylist.clear();          
        wifi.startScan();

        Toast.makeText(this, "Scanning...." + size, Toast.LENGTH_SHORT).show();
        try 
        {
            size = size - 1;
            while (size >= 0) 
            {   
                HashMap<String, String> item = new HashMap<String, String>();                       
                item.put(ITEM_KEY, results.get(size).SSID + "  " + results.get(size).capabilities);

                arraylist.add(item);
                size--;
                adapter.notifyDataSetChanged();                 
            } 
        }
        catch (Exception e)
        { }         
    }    
}

use following permission

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
 <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />