Friends, I want to find all available WiFi networks and display them in a list I have tried as below. But it's not working. I have edited my code, and now I got the result but with all the result that I don't need. I only need names of wifi network in my list.
public class MainActivity extends Activity {
TextView mainText;
WifiManager mainWifi;
WifiReceiver receiverWifi;
List<ScanResult> wifiList;
StringBuilder sb = new StringBuilder();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mainText = (TextView) findViewById(R.id.tv1);
mainWifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
if (mainWifi.isWifiEnabled() == false)
{
// If wifi disabled then enable it
Toast.makeText(getApplicationContext(), "wifi is disabled..making it enabled",
Toast.LENGTH_LONG).show();
mainWifi.setWifiEnabled(true);
}
receiverWifi = new WifiReceiver();
registerReceiver(receiverWifi, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
mainWifi.startScan();
mainText.setText("Starting Scan...");
}
public boolean onCreateOptionsMenu(Menu menu) {
menu.add(0, 0, 0, "Refresh");
return super.onCreateOptionsMenu(menu);
}
public boolean onMenuItemSelected(int featureId, MenuItem item) {
mainWifi.startScan();
mainText.setText("Starting Scan");
return super.onMenuItemSelected(featureId, item);
}
protected void onPause() {
unregisterReceiver(receiverWifi);
super.onPause();
}
protected void onResume() {
registerReceiver(receiverWifi, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
super.onResume();
}
// Broadcast receiver class called its receive method
// when number of wifi connections changed
class WifiReceiver extends BroadcastReceiver {
// This method call when number of wifi connections changed
public void onReceive(Context c, Intent intent) {
sb = new StringBuilder();
wifiList = mainWifi.getScanResults();
sb.append("\n Number Of Wifi connections :"+wifiList.size()+"\n\n");
for(int i = 0; i < wifiList.size(); i++){
sb.append(new Integer(i+1).toString() + ". ");
sb.append((wifiList.get(i)).toString());
sb.append("\n\n");
}
mainText.setText(sb);
}
}
}
You need to create a BroadcastReceiver to listen for Wifi scan results:
private final BroadcastReceiver mWifiScanReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context c, Intent intent) {
if (intent.getAction().equals(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)) {
List<ScanResult> mScanResults = mWifiManager.getScanResults();
// add your logic here
}
}
}
In onCreate() you would assign mWifiManager and initiate a scan:
mWifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
registerReceiver(mWifiScanReceiver,
new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
mWifiManager.startScan();
getScanResults() will return data only if you have appropriate permissions. For this, add one of the following two lines to your AndroidManifest.xml:
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
Also note that in API 23+, permissions must be requested at runtime. (For a lab environment, you can also grant permissions manually in Settings instead—less coding required, but not recommended for an end-user app.)
Note that the code which handles your scan results would run every time a new scan result is available, updating the result.
After Android 6.0
If your Android OS version is 6.0 or above then your application must ask for the following permission at runtime(Either of the following).
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
How to ask the permission at runtime
Just add this code in the onResume method of your activity
@Override
public void onResume()
{
super.onResume();
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
{
if(checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED)
{
requestPermissions(new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, 87);
}
}
}
What will happen if you don't have the above permission at Runtime?
Wifi.getScanResults() will return 0 results.
Many people including me have faced this problem in Nexus 5 phones and referred to it as a "bug".
How to scan and read wifi networks? (Deeper Understanding)
Scanning can be requested by
wifiManager.startScan();
boolean startScan() returns
true or false immediately based on the fact whether the scan has started
successfully or not.
However it starts an asynchronous event which
sends an intent (WifiManager.SCAN_RESULTS_AVAILABLE_ACTION) when
the scan completes. Since the scan results (asynchronous event result) will not be available immediately, you will have to register your activity with a BroadcastReceiver.
Here is the code snippet to read those results(asynchronously) using BroadcastReceiver.
public class WifiScanReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equals(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION))
{
List<ScanResult> scanResults = wifimanager.getScanResults();
// Write your logic to show in the list
}
}
}
You can see this demo on BroadcastReceiver
Relevant links
Scan result returns an empty list in Android 6.0
class WifiReceiver extends BroadcastReceiver {
public void onReceive(Context c, Intent intent) {
sb = new StringBuilder();
wifiList = mainWifi.getScanResults();
for (int i = 0; i < wifiList.size(); i++){
sb.append(new Integer(i+1).toString() + ".");
sb.append((wifiList.get(i)).SSID);
sb.append("\n");
}
mainText.setText(sb);
}
}
