1)Firstly in your XML,Make a Button and TextView :

<Button
    android:id="@+id/btnMyLocation"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/mylocation"/>
 <TextView
     android:id="@+id/tvMyLocation"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:textSize="@dimen/text_Size"
     android:layout_below="@+id/btnMyLocation"/>

2)In your Corresponding Java File,the onCreate method will be:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btnMyLocation=(Button)findViewById(R.id.btnMyLocation);
    tvMyLocation=(TextView)findViewById(R.id.tvMyLocation);
    btnMyLocation.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            gps = new GPSTracker(MainActivity.this);
            // check if GPS enabled
            if(gps.canGetLocation()){
                double latitude = gps.getLatitude();
                double longitude = gps.getLongitude();
                // \n is for new line
               // Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + latitude + "\nLong: " + longitude, Toast.LENGTH_LONG).show();
                tvMyLocation.setText("latitude is :"+ latitude + "&&" + "longitude is :"+ longitude);
            }else{
                // can't get location
                // GPS or Network is not enabled
                // Ask user to enable GPS/network in settings
                gps.showSettingsAlert();
            }
        }
    });
}

Set onClickListener on a Button click.When a button is clicked,it will start a Service gps = new GPSTracker(MainActivity.this) namely GPSTracker.It will first check if GPS on ur Phone is Enabled Or Not.If it is Enabled then it will get Latitude and Longitude,and set it in TextView AND If GPS is NOT Enabled,then it will ask user to Enable GPS.

3)In your GPSTracker Java File,it will extend a Service and code will be as Follows:

public class GPSTracker extends Service implements LocationListener {
    private final Context mContext;
    // flag for GPS status
    boolean isGPSEnabled = false;
    // flag for network status
    boolean isNetworkEnabled = false;
    // flag for GPS status
    boolean canGetLocation = false;
    Location location; // location
    double latitude; // latitude
    double longitude; // longitude
    // 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;
    public GPSTracker(Context context) {
        this.mContext = context;
        getLocation();
    }
    public Location 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);
            if (!isGPSEnabled && !isNetworkEnabled) {
                // no network provider is enabled
            } else {
                this.canGetLocation = true;
                if (isNetworkEnabled) {
                    locationManager.requestLocationUpdates(
                            LocationManager.NETWORK_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d("Network", "Network");
                    if (locationManager != null) {
                        location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
                // if GPS Enabled get lat/long using GPS Services
                if (isGPSEnabled) {
                    if (location == null) {
                        locationManager.requestLocationUpdates(
                                LocationManager.GPS_PROVIDER,
                                MIN_TIME_BW_UPDATES,
                                MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                        Log.d("GPS Enabled", "GPS Enabled");
                        if (locationManager != null) {
                            location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
                            if (location != null) {
                                latitude = location.getLatitude();
                                longitude = location.getLongitude();
                            }
                        }
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return location;
    }
    /**
     * Stop using GPS listener
     * Calling this function will stop using GPS in your app
     */
    public void stopUsingGPS() {
        if (locationManager != null) {
            locationManager.removeUpdates(GPSTracker.this);
        }
    }
    /**
     * Function to get latitude
     */
    public double getLatitude() {
        if (location != null) {
            latitude = location.getLatitude();
        }
        // return latitude
        return latitude;
    }
    /**
     * Function to get longitude
     */
    public double getLongitude() {
        if (location != null) {
            longitude = location.getLongitude();
        }
        // return longitude
        return longitude;
    }
    /**
     * Function to check GPS/wifi enabled
     *
     * @return boolean
     */
    public boolean canGetLocation() {
        return this.canGetLocation;
    }
    /**
     * Function to show settings alert dialog
     * On pressing Settings button will lauch Settings Options
     */
    public void showSettingsAlert() {
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
        // Setting Dialog Title
        alertDialog.setTitle("GPS is settings");
        // Setting Dialog Message
        alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");
        // On pressing Settings button
        alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
            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("Cancel", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                dialog.cancel();
            }
        });
        // Showing Alert Message
        alertDialog.show();
    }
    @Override
    public void onLocationChanged(Location location) {
// TODO Auto-generated method stub
    }
    @Override
    public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
    }
    @
    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
    }
    @Override
    public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
        return null;
    }
}Override
    public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
    }
    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
    }
    @Override
    public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
        return null;
    }
}

I hope it will help you:)