How do I know the map is ready to get used when us

2019-01-03 06:36发布

In the onCreate method, I am making use of the SupportMapFragment to show a map.

    SupportMapFragment fragment = new SupportMapFragment();
    getSupportFragmentManager().beginTransaction()
            .add(android.R.id.content, fragment).commit();

In conjunction to this, I would like to add a marker. The problem is when the call to getMap is null, when can I try again? Is there an event I can register for or is my approach in and of itself wrong?

    mMap = ((SupportMapFragment)(getSupportFragmentManager().findFragmentById(R.id.map))).getMap();
    if(mMap == null)
        //what do I do here?

The map is in fact displaying on the phone however I appear to be having no luck in obtaining the reference to add markers.

UPDATE:

The reason I was creating the SupportMapFragment via the constructor is because the typical setContentView was crashing and did not work. This put me in the predicament where I could not obtain my reference in the onCreate method since I was in fact creating the SupportMapFragment at that time. In further investigation, it appears my setContentView issue was a byproduct of not having both the Google-play-services jar AND the module/src set up as part of the overall project. Upon doing BOTH of these, setContentView now works and I can obtain the reference via getMap() as I would expect.

lots.xml...

<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
          android:id="@+id/map"
          android:name="com.google.android.gms.maps.SupportMapFragment"
          android:layout_width="match_parent"
          android:layout_height="match_parent" />

LotsActivity.java...

public class LotsActivity extends FragmentActivity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.lots);

        GoogleMap mMap;
        mMap = ((SupportMapFragment)(getSupportFragmentManager().findFragmentById(R.id.map))).getMap();
        if(mMap == null)
            //this should not occur now
    }

7条回答
smile是对你的礼貌
2楼-- · 2019-01-03 07:08

if map == null then find the map

 if (mGoogleMap == null)
    {
        SupportMapFragment mapFragment1 = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);

        mapFragment1.getMapAsync(this);
    }

and then call your function onMapReady();

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