Android GPS, Location Manager tutorial

This example demonstrates how to access Android GPS, Location Manager
Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.
Step 2 − Add the following code to res/layout/activity_main.xml.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:gravity="center_horizontal"
   android:orientation="vertical"
   tools:context=".MainActivity">
<Button
   android:id="@+id/btn_start_location_updates"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="40dp"
   android:onClick="startLocationButtonClick"
   android:text="@string/start_updates" />
<Button
   android:id="@+id/btn_stop_location_updates"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="10dp"
   android:enabled="false"
   android:onClick="stopLocationButtonClick"
   android:text="@string/stop_updates" />
<Button
   android:id="@+id/btn_get_last_location"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="10dp"
   android:onClick="showLastKnownLocation"
   android:text="@string/get_last_location" />
<TextView
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="50dp"
   android:gravity="center_horizontal"
   android:text="Location updates will be received only when app is foreground" />
<TextView
   android:id="@+id/location_result"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="20dp"
   android:textColor="#333"
   android:textSize="18sp" />
<TextView
   android:id="@+id/updated_on"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="30dp"
   android:textSize="12sp" />
</LinearLayout>
Step 3 − Add the following code to src/MainActivity.java
package app.com.sample;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import android.Manifest;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.content.IntentSender;
import android.content.pm.PackageManager;
import android.location.Location;
import android.net.Uri;
import android.os.Bundle;
import android.os.Looper;
import android.provider.Settings;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.common.api.ApiException;
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.LocationSettingsStatusCodes;
import com.google.android.gms.location.SettingsClient;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.karumi.dexter.Dexter;
import com.karumi.dexter.PermissionToken;
import com.karumi.dexter.listener.PermissionDeniedResponse;
import com.karumi.dexter.listener.PermissionGrantedResponse;
import com.karumi.dexter.listener.PermissionRequest;
import com.karumi.dexter.listener.single.PermissionListener;
import java.text.DateFormat;
import java.util.Date;
public class MainActivity extends AppCompatActivity {
   private static final String TAG = MainActivity.class.getSimpleName();
   TextView txtLocationResult;
   TextView txtUpdatedOn;
   Button btnStartUpdates;
   Button btnStopUpdates;
   // location last updated time
   private String mLastUpdateTime;
   // location updates interval - 10sec
   private static final long UPDATE_INTERVAL_IN_MILLISECONDS = 10000;
   // fastest updates interval - 5 sec
   // location updates will be received if another app is requesting the locations
   // than your app can handle
   private static final long FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS = 5000;
   private static final int REQUEST_CHECK_SETTINGS = 100;
   // bunch of location related apis
   private FusedLocationProviderClient mFusedLocationClient;
   private SettingsClient mSettingsClient;
   private LocationRequest mLocationRequest;
   private LocationSettingsRequest mLocationSettingsRequest;
   private LocationCallback mLocationCallback;
   private Location mCurrentLocation;
   // boolean flag to toggle the ui
   private Boolean mRequestingLocationUpdates;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      // initialize the necessary libraries
      init();
      // restore the values from saved instance state
      restoreValuesFromBundle(savedInstanceState);
   }
   private void init() {
      txtLocationResult = findViewById(R.id.location_result);
      txtUpdatedOn = findViewById(R.id.updated_on);
      btnStartUpdates = findViewById(R.id.btn_start_location_updates);
      btnStopUpdates = findViewById(R.id.btn_stop_location_updates);
      mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
      mSettingsClient = LocationServices.getSettingsClient(this);
      mLocationCallback = new LocationCallback() {
         @Override
         public void onLocationResult(LocationResult locationResult) {
            super.onLocationResult(locationResult);
            // location is received
            mCurrentLocation = locationResult.getLastLocation();
            mLastUpdateTime = DateFormat.getTimeInstance().format(new Date());
            updateLocationUI();
         }
      };
      mRequestingLocationUpdates = false;
      mLocationRequest = new LocationRequest();
      mLocationRequest.setInterval(UPDATE_INTERVAL_IN_MILLISECONDS);
      mLocationRequest.setFastestInterval(FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS);
      mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
      LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder();
      builder.addLocationRequest(mLocationRequest);
      mLocationSettingsRequest = builder.build();
   }
/**
* Restoring values from saved instance state
*/
   private void restoreValuesFromBundle(Bundle savedInstanceState) {
      if (savedInstanceState != null) {
         if (savedInstanceState.containsKey("is_requesting_updates")) {
            mRequestingLocationUpdates = savedInstanceState.getBoolean("is_requesting_updates");
         }
         if (savedInstanceState.containsKey("last_known_location")) {
            mCurrentLocation = savedInstanceState.getParcelable("last_known_location");
         }
         if (savedInstanceState.containsKey("last_updated_on")) {
            mLastUpdateTime = savedInstanceState.getString("last_updated_on");
         }
      }
      updateLocationUI();
   }
/**
* Update the UI displaying the location data
* and toggling the buttons
*/
   private void updateLocationUI() {
      if (mCurrentLocation != null) {
         txtLocationResult.setText(
         "Lat: " + mCurrentLocation.getLatitude() + ", " +
         "Lng: " + mCurrentLocation.getLongitude()
         );
         // giving a blink animation on TextView
         txtLocationResult.setAlpha(0);
         txtLocationResult.animate().alpha(1).setDuration(300);
         // location last updated time
         txtUpdatedOn.setText("Last updated on: " + mLastUpdateTime);
      }
      toggleButtons();
   }
   @Override
   public void onSaveInstanceState(Bundle outState) {
      super.onSaveInstanceState(outState);
      outState.putBoolean("is_requesting_updates", mRequestingLocationUpdates);
      outState.putParcelable("last_known_location", mCurrentLocation);
      outState.putString("last_updated_on", mLastUpdateTime);
   }
   private void toggleButtons() {
      if (mRequestingLocationUpdates) {
         btnStartUpdates.setEnabled(false);
         btnStopUpdates.setEnabled(true);
      }
       else {
         btnStartUpdates.setEnabled(true);
         btnStopUpdates.setEnabled(false);
      }
   }
/**
* Starting location updates
* Check whether location settings are satisfied and then
* location updates will be requested
*/
   private void startLocationUpdates() {
      mSettingsClient
      .checkLocationSettings(mLocationSettingsRequest)
      .addOnSuccessListener(this, new OnSuccessListener() {
         @SuppressLint("MissingPermission")
         @Override
         public void onSuccess(LocationSettingsResponse locationSettingsResponse) {
         Log.i(TAG, "All location settings are satisfied.");
         Toast.makeText(getApplicationContext(), "Started location updates!",
         Toast.LENGTH_SHORT).show();
         //noinspection MissingPermission
         mFusedLocationClient.requestLocationUpdates(mLocationRequest,
         mLocationCallback, Looper.myLooper());
         updateLocationUI();
      }
   })
   .addOnFailureListener(this, new OnFailureListener() {
      @Override
      public void onFailure(@NonNull Exception e) {
         int statusCode = ((ApiException) e).getStatusCode();
            switch (statusCode) {
               case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
               Log.i(TAG, "Location settings are not satisfied. Attempting to upgrade " + "location settings ");
               try {
                  // Show the dialog by calling startResolutionForResult(), and check the
                  // result in onActivityResult().
                  ResolvableApiException rae = (ResolvableApiException) e;
                  rae.startResolutionForResult(MainActivity.this, REQUEST_CHECK_SETTINGS);
               }
               catch (IntentSender.SendIntentException sie) {
                  Log.i(TAG, "PendingIntent unable to execute request.");
               }
               break;
               case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
               String errorMessage = "Location settings are inadequate, and cannot be " + "fixed here. Fix in Settings.";
               Log.e(TAG, errorMessage);
               Toast.makeText(MainActivity.this, errorMessage, Toast.LENGTH_LONG).show();
            }
            updateLocationUI();
         }
      });
   }
   public void startLocationButtonClick(View view) {
      // Requesting ACCESS_FINE_LOCATION using Dexter library
      Dexter.withActivity(this)
      .withPermission(Manifest.permission.ACCESS_FINE_LOCATION)
      .withListener(new PermissionListener() {
         @Override
         public void onPermissionGranted(PermissionGrantedResponse response) {
            mRequestingLocationUpdates = true;
            startLocationUpdates();
         }
         @Override
         public void onPermissionDenied(PermissionDeniedResponse response) {
            if (response.isPermanentlyDenied()) {
               // open device settings when the permission is
               // denied permanently
               openSettings();
            }
         }
         @Override
         public void onPermissionRationaleShouldBeShown(PermissionRequest permission,
         PermissionToken token) {
            token.continuePermissionRequest();
         }
      }).check();
   }
   public void stopLocationButtonClick(View view) {
      mRequestingLocationUpdates = false;
      stopLocationUpdates();
   }
   public void stopLocationUpdates() {
      // Removing location updates
      mFusedLocationClient
      .removeLocationUpdates(mLocationCallback)
      .addOnCompleteListener(this, new OnCompleteListener() {
         @Override
         public void onComplete(@NonNull Task task) {
            Toast.makeText(getApplicationContext(), "Location updates stopped!",
            Toast.LENGTH_SHORT).show();
            toggleButtons();
         }
      });
   }
   public void showLastKnownLocation(View view) {
      if (mCurrentLocation != null) {
         Toast.makeText(getApplicationContext(), "Lat: " + mCurrentLocation.getLatitude() + ", Lng: " + mCurrentLocation.getLongitude(), Toast.LENGTH_LONG).show();
      }
       else {
         Toast.makeText(getApplicationContext(), "Last known location is not available!",
         Toast.LENGTH_SHORT).show();
      }
   }
   @Override
   protected void onActivityResult(int requestCode, int resultCode, Intent data) {
      // Check for the integer request code originally supplied to startResolutionForResult().
      if (requestCode == REQUEST_CHECK_SETTINGS) {
         switch (resultCode) {
            case Activity.RESULT_OK:
            Log.e(TAG, "User agreed to make required location settings changes.");
            // Nothing to do. startLocationupdates() gets called in onResume again.
               break;
               case Activity.RESULT_CANCELED:
               Log.e(TAG, "User chose not to make required location settings changes.");
               mRequestingLocationUpdates = false;
               break;
            }
         }
      }
      private void openSettings() {
         Intent intent = new Intent();
         intent.setAction(
         Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
         Uri uri = Uri.fromParts("package",
         BuildConfig.APPLICATION_ID, null);
         intent.setData(uri);
         intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
         startActivity(intent);
      }
      @Override
      public void onResume() {
         super.onResume();
         // Resuming location updates depending on button state and
         // allowed permissions
         if (mRequestingLocationUpdates && checkPermissions()) {
            startLocationUpdates();
         }
         updateLocationUI();
      }
      private boolean checkPermissions() {
         int permissionState = ActivityCompat.checkSelfPermission(this,
         Manifest.permission.ACCESS_FINE_LOCATION);
         return permissionState == PackageManager.PERMISSION_GRANTED;
      }
      @Override
      protected void onPause() {
         super.onPause();
         if (mRequestingLocationUpdates) {
            // pausing location updates
            stopLocationUpdates();
         }
      }
   }
Step 4 − Add the following code to androidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="app.com.sample">
   <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
      <application
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
         <activity android:name=".MainActivity">
            <intent-filter>
               <action android:name="android.intent.action.MAIN" />
               <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>
Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from the android studio, open one of your project's activity files and click Run  icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −