On Android, Google Now serves as the virtual assistant Siri is on iOS and Cortana is on Windows Phone (WP). Thus, Google Now can take voice commands and act on them. But up until recently that did not include toggling certain system settings. The good news is that as of this moment Google Now is in fact able to toggle your Wi-Fi and Bluetooth connections on or off, as well as the flashlight functionality enabled by your phone’s LED flash. Before, if you told Google Now to “turn Wi-Fi off” for example, it would simply take you to the relevant menu inside Settings (and this is still what happens if you use Google Now on older versions of the OS). Now , when you tell it to turn Wi-Fi on or off, it simply does that without no hesitation. Once you’ve told Google Now what to do, you get audio feedback letting you know that the action has been performed, as well as a card and a small toggle (as you can see from the screenshots below). The toggle that’s displayed helps you quickly revert an action if you made a mistake.For now just these three commands (wi-fi , bluetooth , LED flash) work like this.
Note : This works only on Android v5.0 lollipop.