How to update WiFi state using BroadcastReceiver

This BroadcastReceiver will trigger anytime "Mobile data" disconnects or connects.

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

TextView wifistate = (TextView) findViewById(R.id.infowifi);

this.registerReceiver(mWifiStateChangedReceiver,new IntentFilter(WifiManager.WIFI_STATE_CHANGED_ACTION));

}

@Override
public void onBackPressed() {
    
    unregisterReceiver(mWifiStateChangedReceiver); // this will unregister Receiver
    this.finish(); // this will finish ThisActivity
    super.onBackPressed();
}

private BroadcastReceiver mWifiStateChangedReceiver