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Google Map

Full Google Map Introduction
(https://www.raywenderlich.com/144066/introduction-google-maps-api-android)

Mapview Tutorial
(https://www.bignerdranch.com/blog/embedding-custom-views-with-mapview-v2/)

2 Map Object(1.mapFragment 2.mapView)

Set permission

The template adds the following in the manifests/AndroidManifest.xml:

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

A declaration of the ACCESS_FINE_LOCATION permission. This is required to access the user’s precise location.

2.The com.google.android.geo.API_KEY meta-data. This is used to specify the API key.

<meta-data
        android:name="com.google.android.geo.API_KEY"
        android:value="@string/google_maps_key" />

3.The template also adds a Google Play Services dependency to build.gradle.
This dependency exposes the Google Maps and Location Services APIs to the application.

compile 'com.google.android.gms:play-services:VERSION_HERE'

Set Map Fragment

// 1
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
 
  private GoogleMap mMap;
 
  // 2
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);
    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
        .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
  }
 
  // 3
  @Override
  public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
 
    // Add a marker in Sydney and move the camera
    LatLng sydney = new LatLng(-34, 151);
    mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
  }
}

Using the Google Maps APIs

Head back to google_maps_api.xml, replace the value of google_maps_key key with the copied API key.

Build and run again. You should see a map with a red marker on the screen.

Setting up Play Services Connection

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback,          GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener,           GoogleMap.OnMarkerClickListener, LocationListener

Here’s what each interface does:

1.GoogleApiClient.ConnectionCallbacks provides callbacks that are triggered when the client is connected (onConnected()) or temporarily disconnected (onConnectionSuspended()) from the service.
2.GoogleApiClient.OnConnectionFailedListener provides a callback method (onConnectionFailed()) that is triggered when an attempt to connect the client to the service results in a failure.
3.GoogleMap.OnMarkerClickListener defines the onMarkerClick() which is called when a marker is clicked or tapped.
4.LocationListener defines the onLocationChanged() which is called when a user’s location changes. This method is only called if the LocationListener has been registered.

private GoogleApiClient mGoogleApiClient;

onCreate()

// 1
if (mGoogleApiClient == null) {
mGoogleApiClient = new GoogleApiClient.Builder(this)
  .addConnectionCallbacks(this)
  .addOnConnectionFailedListener(this)
  .addApi(LocationServices.API)
  .build();
}

Method()

@Override
protected void onStart() {
  super.onStart();
  // 2
  mGoogleApiClient.connect();
}
@Override
protected void onStop() {
  super.onStop();
  // 3
  if( mGoogleApiClient != null && mGoogleApiClient.isConnected() ) {
    mGoogleApiClient.disconnect();
  }
}

Here’s what’s going on above:

1.Instantiates the mGoogleApiClient field if it’s null.
2.Initiates a background connection of the client to Google Play services.
3.Closes the connection to Google Play services if the client is not null and is connected.

onMapReady()

mMap.getUiSettings().setZoomControlsEnabled(true); 
mMap.setOnMarkerClickListener(this); 

setTitle

LatLng myPlace = new LatLng(40.73, -73.99);  // this is New York 
mMap.addMarker(new MarkerOptions().position(myPlace).title("My Favorite City"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(myPlace));

moveCamera()

mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(myPlace, 12));

User Permissions

Starting with Android 6.0, user permissions are handled a little differently than before.
You don’t request permission during the installation of your app;
rather, you request them at run time when the permission is actually required.

private static final int LOCATION_PERMISSION_REQUEST_CODE = 1;  

setUpMap()

private void setUpMap() {
  if (ActivityCompat.checkSelfPermission(this,
    android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this, new String[]
      {android.Manifest.permission.ACCESS_FINE_LOCATION}, LOCATION_PERMISSION_REQUEST_CODE);  
    return;
  }
}

onConnected()

@Override
public void onConnected(@Nullable Bundle bundle) {
  setUpMap();
}