Enable GPS in app

MainActivity.java

package catvinhquang.enablegps;

import android.Manifest;
import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Location;
import android.os.Bundle;
import android.os.Looper;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.text.method.ScrollingMovementMethod;
import android.view.View;
import android.widget.TextView;

import com.google.android.gms.common.api.ResolvableApiException;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationCallback;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationResult;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.location.LocationSettingsRequest;
import com.google.android.gms.location.LocationSettingsResponse;
import com.google.android.gms.location.SettingsClient;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;

/**
 * Created by quangcv on 15/08/2018.
 */

public class MainActivity extends Activity {

    static final int REQUEST_GPS = 100;
    static final int REQUEST_PERMISSION_LOCATION = 101;
    static final LocationRequest locationRequest;

    static {
        locationRequest = new LocationRequest();
        locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        locationRequest.setInterval(1000);
        locationRequest.setFastestInterval(1000);
        locationRequest.setNumUpdates(1);
    }

    final StringBuilder consoleBuilder = new StringBuilder();
    TextView console;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        console = new TextView(this);
        console.setMovementMethod(new ScrollingMovementMethod());
        console.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                requestGPS();
            }
        });
        console.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View v) {
                clear();
                return true;
            }
        });
        clear();
        setContentView(console);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_GPS) {
            if (resultCode == RESULT_OK) {
                log("GPS enabled");
                requestLocation();
            } else {
                log("Request GPS is canceled");
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        if (requestCode == REQUEST_PERMISSION_LOCATION) {
            if (grantResults[0] == PackageManager.PERMISSION_GRANTED && grantResults[1] == PackageManager.PERMISSION_GRANTED) {
                log("Permission granted");
                requestLocation();
            } else {
                log("Permission denied");
            }
        }
    }

    void requestGPS() {
        LocationSettingsRequest settingsRequest = new LocationSettingsRequest.Builder()
                .addLocationRequest(locationRequest)
                .setAlwaysShow(true)
                .build();

        SettingsClient settingsClient = LocationServices.getSettingsClient(this);
        Task<LocationSettingsResponse> task = settingsClient.checkLocationSettings(settingsRequest);
        task.addOnSuccessListener(new OnSuccessListener<LocationSettingsResponse>() {
            @Override
            public void onSuccess(LocationSettingsResponse locationSettingsResponse) {
                log("GPS enabled");
                requestLocation();
            }
        });
        task.addOnFailureListener(this, new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                log("GPS disabled");
                if (e instanceof ResolvableApiException) {
                    try {
                        log("Requesting GPS");
                        ResolvableApiException resolvable = (ResolvableApiException) e;
                        resolvable.startResolutionForResult(MainActivity.this, REQUEST_GPS);
                    } catch (Throwable t) {
                        t.printStackTrace();
                    }
                }
            }
        });
    }

    void requestLocation() {
        log("Requesting location");
        FusedLocationProviderClient providerClient = LocationServices.getFusedLocationProviderClient(this);
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            log("Request location is canceled");
            log("Request permission");
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION}, REQUEST_PERMISSION_LOCATION);
            return;
        }
        providerClient.requestLocationUpdates(locationRequest, new LocationCallback() {
            @Override
            public void onLocationResult(LocationResult locationResult) {
                Location location = locationResult.getLastLocation();
                log(location.getProvider() + " | " + location.getLatitude() + ", " + location.getLongitude());
            }
        }, Looper.myLooper());
    }

    void log(String message) {
        consoleBuilder.append(message).append("\n");
        console.setText(consoleBuilder);
    }

    void clear() {
        consoleBuilder.delete(0, consoleBuilder.length());
        consoleBuilder.append("Touch to continue, please!\nAnd long touch to clear :)\n");
        console.setText(consoleBuilder);
    }

}

Dependency:
compile 'com.google.android.gms:play-services-location:15.0.1'