Android: switch wifi on/off

activity.java

public void toggleWifi() {
  // Get the WifiManager service from the context
  WifiManager wm = (WifiManager) this.getSystemService(Context.WIFI_SERVICE);
  
  // Read the current state. True is On, False is Off
  boolean currentState = wm.isWifiEnabled();
  
  // And now, switch to the other state
  wm.setWifiEnabled(!currentState);
  
  // You're done :)
  // Note that it can take some time for the wifi to reconnect
  // when you switch it on.
}

AndroidManifest.xml

<!--  Add these permissions to your android manifest -->
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>