title: Google map integration in android not showing map
body: <p>I have a issue in google map integration for android,
  When i create a map activity and then integrate to google api getting gray background, but when i create a new project and then integrate new project to google map that will work perfectly, 
  My actual project can't integrate to google map, can anyone help me,
  i mean the issue in the map key how solve it.</p>
  
  <pre><code>public class MapViewActivity extends FragmentActivity implements OnMapReadyCallback{
  
  private GoogleMap mMap;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_map_view);
      // 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);
  }
  
  
  /**
   * Manipulates the map once available.
   * This callback is triggered when the map is ready to be used.
   * This is where we can add markers or lines, add listeners or move the camera. In this case,
   * we just add a marker near Sydney, Australia.
   * If Google Play services is not installed on the device, the user will be prompted to install
   * it inside the SupportMapFragment. This method will only be triggered once the user has
   * installed Google Play services and returned to the app.
   */
  @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));
  }
  
  }
  </code></pre>
  
  <p>This is the code of my <code>mapactivity</code>.</p>