I am using following code for GPS on/off.
//Enable GPS
Intent intent = new Intent(\"android.location.GPS_ENABLED_CHANGE\");
intent.putExtra(\"enabled\", true
Use this for turning GPS ON and reverse the condition to put GPS OFF
Intent intent = new Intent("android.location.GPS_ENABLED_CHANGE");
intent.putExtra("enabled", true);
this.ctx.sendBroadcast(intent);
String provider = Settings.Secure.getString(ctx.getContentResolver(), Settings.Secure.LOCATION_PROVIDERS_ALLOWED);
if(!provider.contains("gps")){ //if gps is disabled
final Intent poke = new Intent();
poke.setClassName("com.android.settings", "com.android.settings.widget.SettingsAppWidgetProvider");
poke.addCategory(Intent.CATEGORY_ALTERNATIVE);
poke.setData(Uri.parse("3"));
this.ctx.sendBroadcast(poke);
}