title: Google Maps Android API Removing markers when switching floors
body: <p>Im working on a Android app project that needs an indoor map. The location I am using has the floors available on Google maps. Im using the Google Maps Android API. I have markers set on the initial level shown. How can I remove/hide these markers and replace them with new one when I switch floors? 
  here is my java code:</p>
  
  <pre><code>package com.me.maps;
  
  import android.support.v4.app.FragmentActivity;
  import android.os.Bundle;
  
  import com.google.android.gms.maps.CameraUpdateFactory;
  import com.google.android.gms.maps.GoogleMap;
  import com.google.android.gms.maps.OnMapReadyCallback;
  import com.google.android.gms.maps.SupportMapFragment;
  import com.google.android.gms.maps.model.LatLng;
  import com.google.android.gms.maps.model.MarkerOptions;
  
  public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
  
      private GoogleMap mMap;
  
      @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);
      }
  
  
  
      /**
       * 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 Milwaukee, Wisconsin.
       * 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 mpm = new LatLng(43.0408468, -87.921474);
          LatLng planetarium = new LatLng(43.040622,-87.920798);
          LatLng theater = new LatLng(43.040497,-87.920640);
          LatLng marketplace = new LatLng(43.040779,-87.921717);
          mMap.addMarker(new MarkerOptions().position(mpm).title("Milwaukee Public Museum"));
          mMap.addMarker(new MarkerOptions().position(planetarium).title("The Daniel M. Soref National Geographic Planetarium"));
          mMap.addMarker(new MarkerOptions().position(theater).title("The Daniel M. Soref National Geographic Theater"));
          mMap.addMarker(new MarkerOptions().position(marketplace).title("Museum Marketplace"));
          mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(mpm, 18));
      }
  }
  </code></pre>