Android - how to turn on wifi programmatically and wait until it not enabled

Question

I want to send data over local network using wifi. Before sending data I check the wifi state, and, if it not enabled, ask the user and turn wifi on. The problem is if I turn wifi on and try to use it immediately, I have got an error cause the wifi need some time to be turned on.

So, as I think, I need to turn wifi on and set the handler which will be called when wifi goes to enabled state. But WifiManager doesn't provide such methods with handlers. How I can catch changing of wifi state?

UPD

How I turn wifi on:

WifiManager wifi = WifiUtils.getWifi( getApplicationContext() );
if (WifiUtils.isWifiEnabled( wifi)) return true;
wifi.setWifiEnabled(true);
//---
public static WifiManager getWifi( Context ctx) 
{
    return (WifiManager)ctx.getSystemService(ctx.WIFI_SERVICE);
}

public static boolean isWifiEnabled( WifiManager wifi)
{
    if (wifi==null) return false;
    if (wifi.getWifiState()!=wifi.WIFI_STATE_ENABLED) return false;
    return true;
}

Answer 1

First of all if you want to check if wifi is connected or not You can use this

ConnectivityManager cm = (ConnectivityManager) getSystemService(
        Context.CONNECTIVITY_SERVICE);
NetworkInfo wifiNetwork = cm.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
if (wifiNetwork != null && wifiNetwork.isConnected()) {

}
else{
//ask your user to turn on wifi
}

Now if you want to check whether the device can access internet even if wifi is on, then you could do something like

if (wifiNetwork != null && wifiNetwork.isConnected()) {

HttpURLConnection conn= (HttpURLConnection) url.openConnection();
            conn.setConnectTimeout(10000);
            int responseCode = conn.getResponseCode();
            if(responseCode == 200){

                //internet access
            }
            else {
                //no internet access
            }
}

If you want to handle wifi state changes then you can try BroadcastReceiver when wifi or 3g network state changed or Android: Getting Notified of Connectivity Changes

However if you want to turn wifi on programmatically refer this SO question .Basically you will need to do something like this

WifiManager wManager = (WifiManager)this.getApplicationContext().getSystemService(Context.WIFI_SERVICE);

wManager.setWifiEnabled(booleanValue); //true for on and false for off

And of course you will need to add necessary permissions in your AndroidManifest.xml like

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