How to get User location information via android system

Get User Location.java

package com.example.robpercival.locationdemo;

import android.app.Activity;
import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;

public class MainActivity extends Activity implements LocationListener {

    LocationManager locationManager; // creating an object of class Location manager
    String provider;

    @Override // An Override function that responsible for the code running in the background and connot affect the UI
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); // calling the location service to the Location manager class

        provider = locationManager.getBestProvider(new Criteria(), false); // get the location from the best provider based on a certain criteria like 
                                                                           // low power consuming, false to check up till meet the criteria - true to
                                                                           //use the current criteria.

        Location location = locationManager.getLastKnownLocation(provider);

        if (location != null) {

            Log.i("Location Info", "Location achieved!");

        } else {

            Log.i("Location Info", "No location :(");

        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override  // A method responsible for requesting the user current location once the app being resumed in use.
    protected void onResume() {
        super.onResume();

        locationManager.requestLocationUpdates(provider, 400, 1, this); // get location via provider, if min time, if min dist, for this context

    }

    @Override // A method that handles what should happen when the app is in the background
    protected void onPause() {
        super.onPause();

        locationManager.removeUpdates(this); // Updates should be removed due not to consume alot of battery power

    }

    @Override // A Generated method related to [implement LocationListener extended class]  detects if user location changed
    public void onLocationChanged(Location location) {

        Double lat = location.getLatitude();  // get user latitude
        Double lng = location.getLongitude(); // get user longtide

        Log.i("Location info: Lat", lat.toString());
        Log.i("Location info: Lng", lng.toString());

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {

    }

    @Override
    public void onProviderEnabled(String provider) {

    }

    @Override
    public void onProviderDisabled(String provider) {

    }

    public void getLocation(View view) {  // method to get the last user known location if the provider service is not available

        Location location = locationManager.getLastKnownLocation(provider); // get last known location

        onLocationChanged(location);  // use this value to return to the locationChanged method


    }

}