package com.example.ybs.myapplication

 import android.annotation.SuppressLint

 import android.net.wifi.WifiManager

 import android.support.v7.app.AppCompatActivity

 import android.os.Bundle

 import kotlinx.android.synthetic.main.activity_main.*

 import java.net.NetworkInterface

 class MainActivity : AppCompatActivity() {

     override fun onCreate(savedInstanceState: Bundle?) {

         super.onCreate(savedInstanceState)

         setContentView(R.layout.activity_main);

         var mac = getLocalMacAddress();

         txtInfo.text = mac;

     }

     @SuppressLint("WifiManagerLeak")

     fun getLocalMacAddress():String{

          var Context = this.applicationContext;

         var wifi= getSystemService(WIFI_SERVICE) as WifiManager;

         var info=wifi.connectionInfo;

         return info.macAddress;

     }

 }

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

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