How to enable/disable WiFi from an application?

try this code

 Intent gpsOptionsIntent = new Intent(  android.provider.Settings.ACTION_WIFI_SETTINGS);  
            startActivityForResult(gpsOptionsIntent,0); 

To enable/disable WiFi in your application you need to use WiFiManager class. Create an Object of WiFiManager class to get the services of WiFi.

WifiManager wifi;
wifi=(WifiManager)getSystemService(Context.WIFI_SERVICE);

wifi.setWifiEnabled(false);//Turn off Wifi

wifi.setWifiEnabled(true);//Turn on Wifi

And you have to put the following permissions in AndroidManifest.xml

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

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

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

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

To get the whole sample code of enable/disable Wifi in android with UI visit this website

WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
wifi.setWifiEnabled(false); // true or false to activate/deactivate wifi

You also need to request the permission in your AndroidManifest.xml :

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