Before couple of months, I created GPSTracker library to help me to get GPS locations. In case you need to view GPSTracker > getLocation

Demo

AndroidManifest.xml

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

Activity

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;

public class MainActivity extends Activity {

    TextView textview;

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

        // check if GPS enabled
        GPSTracker gpsTracker = new GPSTracker(this);

        if (gpsTracker.getIsGPSTrackingEnabled())
        {
            String stringLatitude = String.valueOf(gpsTracker.latitude);
            textview = (TextView)findViewById(R.id.fieldLatitude);
            textview.setText(stringLatitude);

            String stringLongitude = String.valueOf(gpsTracker.longitude);
            textview = (TextView)findViewById(R.id.fieldLongitude);
            textview.setText(stringLongitude);

            String country = gpsTracker.getCountryName(this);
            textview = (TextView)findViewById(R.id.fieldCountry);
            textview.setText(country);

            String city = gpsTracker.getLocality(this);
            textview = (TextView)findViewById(R.id.fieldCity);
            textview.setText(city);

            String postalCode = gpsTracker.getPostalCode(this);
            textview = (TextView)findViewById(R.id.fieldPostalCode);
            textview.setText(postalCode);

            String addressLine = gpsTracker.getAddressLine(this);
            textview = (TextView)findViewById(R.id.fieldAddressLine);
            textview.setText(addressLine);
        }
        else
        {
            // can't get location
            // GPS or Network is not enabled
            // Ask user to enable GPS/network in settings
            gpsTracker.showSettingsAlert();
        }
    }

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

GPS Tracker

import java.io.IOException;
import java.util.List;
import java.util.Locale;

import android.app.AlertDialog;
import android.app.Service;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;
import android.util.Log;

/**
 * Create this Class from tutorial : 
 * http://www.androidhive.info/2012/07/android-gps-location-manager-tutorial
 * 
 * For Geocoder read this : http://stackoverflow.com/questions/472313/android-reverse-geocoding-getfromlocation
 * 
 */

public class GPSTracker extends Service implements LocationListener {

    // Get Class Name
    private static String TAG = GPSTracker.class.getName();

    private final Context mContext;

    // flag for GPS Status
    boolean isGPSEnabled = false;

    // flag for network status
    boolean isNetworkEnabled = false;

    // flag for GPS Tracking is enabled 
    boolean isGPSTrackingEnabled = false;

    Location location;
    double latitude;
    double longitude;

    // How many Geocoder should return our GPSTracker
    int geocoderMaxResults = 1;

    // The minimum distance to change updates in meters
    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters

    // The minimum time between updates in milliseconds
    private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute

    // Declaring a Location Manager
    protected LocationManager locationManager;

    // Store LocationManager.GPS_PROVIDER or LocationManager.NETWORK_PROVIDER information
    private String provider_info;

    public GPSTracker(Context context) {
        this.mContext = context;
        getLocation();
    }

    /**
     * Try to get my current location by GPS or Network Provider
     */
    public void getLocation() {

        try {
            locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE);

            //getting GPS status
            isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

            //getting network status
            isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

            // Try to get location if you GPS Service is enabled
            if (isGPSEnabled) {
                this.isGPSTrackingEnabled = true;

                Log.d(TAG, "Application use GPS Service");

                /*
                 * This provider determines location using
                 * satellites. Depending on conditions, this provider may take a while to return
                 * a location fix.
                 */

                provider_info = LocationManager.GPS_PROVIDER;

            } else if (isNetworkEnabled) { // Try to get location if you Network Service is enabled
                this.isGPSTrackingEnabled = true;

                Log.d(TAG, "Application use Network State to get GPS coordinates");

                /*
                 * This provider determines location based on
                 * availability of cell tower and WiFi access points. Results are retrieved
                 * by means of a network lookup.
                 */
                provider_info = LocationManager.NETWORK_PROVIDER;

            } 

            // Application can use GPS or Network Provider
            if (!provider_info.isEmpty()) {
                locationManager.requestLocationUpdates(
                    provider_info,
                    MIN_TIME_BW_UPDATES,
                    MIN_DISTANCE_CHANGE_FOR_UPDATES, 
                    this
                );

                if (locationManager != null) {
                    location = locationManager.getLastKnownLocation(provider_info);
                    updateGPSCoordinates();
                }
            }
        }
        catch (Exception e)
        {
            //e.printStackTrace();
            Log.e(TAG, "Impossible to connect to LocationManager", e);
        }
    }

    /**
     * Update GPSTracker latitude and longitude
     */
    public void updateGPSCoordinates() {
        if (location != null) {
            latitude = location.getLatitude();
            longitude = location.getLongitude();
        }
    }

    /**
     * GPSTracker latitude getter and setter
     * @return latitude
     */
    public double getLatitude() {
        if (location != null) {
            latitude = location.getLatitude();
        }

        return latitude;
    }

    /**
     * GPSTracker longitude getter and setter
     * @return
     */
    public double getLongitude() {
        if (location != null) {
            longitude = location.getLongitude();
        }

        return longitude;
    }

    /**
     * GPSTracker isGPSTrackingEnabled getter.
     * Check GPS/wifi is enabled
     */
    public boolean getIsGPSTrackingEnabled() {

        return this.isGPSTrackingEnabled;
    }

    /**
     * Stop using GPS listener
     * Calling this method will stop using GPS in your app
     */
    public void stopUsingGPS() {
        if (locationManager != null) {
            locationManager.removeUpdates(GPSTracker.this);
        }
    }

    /**
     * Function to show settings alert dialog
     */
    public void showSettingsAlert() {
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

        //Setting Dialog Title
        alertDialog.setTitle(R.string.GPSAlertDialogTitle);

        //Setting Dialog Message
        alertDialog.setMessage(R.string.GPSAlertDialogMessage);

        //On Pressing Setting button
        alertDialog.setPositiveButton(R.string.action_settings, new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) 
            {
                Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                mContext.startActivity(intent);
            }
        });

        //On pressing cancel button
        alertDialog.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) 
            {
                dialog.cancel();
            }
        });

        alertDialog.show();
    }

    /**
     * Get list of address by latitude and longitude
     * @return null or List<Address>
     */
    public List<Address> getGeocoderAddress(Context context) {
        if (location != null) {

            Geocoder geocoder = new Geocoder(context, Locale.ENGLISH);

            try {
                /**
                 * Geocoder.getFromLocation - Returns an array of Addresses 
                 * that are known to describe the area immediately surrounding the given latitude and longitude.
                 */
                List<Address> addresses = geocoder.getFromLocation(latitude, longitude, this.geocoderMaxResults);

                return addresses;
            } catch (IOException e) {
                //e.printStackTrace();
                Log.e(TAG, "Impossible to connect to Geocoder", e);
            }
        }

        return null;
    }

    /**
     * Try to get AddressLine
     * @return null or addressLine
     */
    public String getAddressLine(Context context) {
        List<Address> addresses = getGeocoderAddress(context);

        if (addresses != null && addresses.size() > 0) {
            Address address = addresses.get(0);
            String addressLine = address.getAddressLine(0);

            return addressLine;
        } else {
            return null;
        }
    }

    /**
     * Try to get Locality
     * @return null or locality
     */
    public String getLocality(Context context) {
        List<Address> addresses = getGeocoderAddress(context);

        if (addresses != null && addresses.size() > 0) {
            Address address = addresses.get(0);
            String locality = address.getLocality();

            return locality;
        }
        else {
            return null;
        }
    }

    /**
     * Try to get Postal Code
     * @return null or postalCode
     */
    public String getPostalCode(Context context) {
        List<Address> addresses = getGeocoderAddress(context);

        if (addresses != null && addresses.size() > 0) {
            Address address = addresses.get(0);
            String postalCode = address.getPostalCode();

            return postalCode;
        } else {
            return null;
        }
    }

    /**
     * Try to get CountryName
     * @return null or postalCode
     */
    public String getCountryName(Context context) {
        List<Address> addresses = getGeocoderAddress(context);
        if (addresses != null && addresses.size() > 0) {
            Address address = addresses.get(0);
            String countryName = address.getCountryName();

            return countryName;
        } else {
            return null;
        }
    }

    @Override
    public void onLocationChanged(Location location) {
    }

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

    @Override
    public void onProviderEnabled(String provider) {
    }

    @Override
    public void onProviderDisabled(String provider) {
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

Note

If the method / answer doesn't work. You need to use the official Google Provider: FusedLocationProviderApi.

Article: Getting the Last Known Location

onLocationChanged gets called every time when your location updates , so keep & update a global value and take that value on your Button click to do what you want

 private LatLng latLng;

       @Override
        public void onLocationChanged(Location location) {
        if(location!=null){
         latLng = new LatLng(location.getLatitude(), location.getLongitude()); }
    }

or based on time or distance you can get the location as well use android.location.LocationListener() see Edit for that,

If you want to manually call onLocationChanged after a time period even the location is not changed use below

 LocationRequest  mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(30000); //5 seconds
    mLocationRequest.setFastestInterval(30000); //3 seconds
    mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
    //mLocationRequest.setSmallestDisplacement(0.1F); //1/10 meter

    if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);

Edit : This is the location listener you can use this separately without the above if you want

    private LocationManager locationManager;
    private android.location.LocationListener myLocationListener;

    public void checkLocation() {

        String serviceString = Context.LOCATION_SERVICE;
        locationManager = (LocationManager) getSystemService(serviceString);


        if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            return;
        }


        myLocationListener = new android.location.LocationListener() {
            public void onLocationChanged(Location locationListener) {

                if (isGPSEnabled(YourActivityName.this)) {
                    if (locationListener != null) {
                        if (ActivityCompat.checkSelfPermission(YourActivityName.this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(YourActivityName.this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                            return;
                        }

                        if (locationManager != null) {
                            location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
                            if (location != null) {
                                latitude = location.getLatitude();
                                longitude = location.getLongitude();
                            }
                        }
                    }
                } else if (isInternetConnected(YourActivityName.this)) {
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }



            }

            public void onProviderDisabled(String provider) {

            }

            public void onProviderEnabled(String provider) {

            }

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

            }
        }; 

locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 1, myLocationListener); 
}

isInternetConnected method

public static boolean isInternetConnected(Context ctx) {
        ConnectivityManager connectivityMgr = (ConnectivityManager) ctx
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo wifi = connectivityMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
        NetworkInfo mobile = connectivityMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
        // Check if wifi or mobile network is available or not. If any of them is
        // available or connected then it will return true, otherwise false;
        if (wifi != null) {
            if (wifi.isConnected()) {
                return true;
            }
        }
        if (mobile != null) {
            if (mobile.isConnected()) {
                return true;
            }
        }
        return false;
    }

isGpsEnabled method

  public boolean isGPSEnabled(Context mContext) {
        LocationManager locationManager = (LocationManager) mContext.getSystemService(Context.LOCATION_SERVICE);
        return locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
    }

Note : Now do not get confuse. There are 3 ways mentioned here.

1.use onLocationChanged automatically

2. use onLocationChanged manually

3. use android.location.LocationListener() added the full implementation (this will not help you to learn but to get a data. Go through these lines and understand them by searching what happen actually )