设置初始缩放

我使用地图，最初如何设置缩放比例（大约只能看到这些标记所在的城市）？

我的 MapActivity 类：

public class MapActivity extends AppCompatActivity implements OnMapReadyCallback {
private ChildEventListener mChildEventListener;
private DatabaseReference mFruitRef = FirebaseDatabase.getInstance().getReference("Fruit");

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_map);
    createMapView();
}

private void createMapView() {
    MapFragment mapFragment = (MapFragment) getFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
}

@Override
public void onMapReady(GoogleMap googleMap) {
    googleMap.setOnMarkerClickListener(marker -> false);
    googleMap.getUiSettings().setZoomControlsEnabled(true);
    Marker marker = new Marker("Orange", 47.000327, 28.867950, "some info");
    Marker marker2 = new Marker("Bananas", 47.045029, 28.861427, "some info");
    Marker marker3 = new Marker("Peaches", 47.024204, 28.889236, "some info");
    mFruitRef.push().setValue(marker);
    mFruitRef.push().setValue(marker2);
    mFruitRef.push().setValue(marker3);

    googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);

    //get marker info from Firebase Database and add to map
    addMarkersToMap(googleMap);

    if (ActivityCompat.checkSelfPermission(this,
            android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
            && ActivityCompat.checkSelfPermission(this,
            android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    googleMap.setMyLocationEnabled(true);
}

@Override
public void onStop() {
    if (mChildEventListener != null)
        mFruitRef.removeEventListener(mChildEventListener);
    super.onStop();
}

private void addMarkersToMap(GoogleMap map) {
    mChildEventListener = mFruitRef.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            Marker marker = dataSnapshot.getValue(Marker.class);
            String name = marker.getName();
            String description = marker.getDescription();
            double latitude = marker.getLatitude();
            double longitude = marker.getLongitude();
            LatLng location = new LatLng(latitude, longitude);
            map.addMarker(new MarkerOptions().title(name).snippet(description).position(location));
        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}
}