Aaron McIver Aaron McIver - 2 months ago 7
Android Question

How do I know the map is ready to get used when using the SupportMapFragment?

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
}

Answer

EDIT: getMap is deprecated now

The problem is when the call to getMap is null, when can I try again?

That depends upon the nature of the problem.

If you set up the SupportMapFragment via the <fragment> element in the layout, you can call getMap() successfully in onCreate(). But, if you create the SupportMapFragment via the constructor, that's too soon -- the GoogleMap does not yet exist. You can extend SupportMapFragment and override onActivityCreated(), as getMap() is ready by then.

However, getMap() can also return null for a bigger problem, such as Google Play Services not being installed. You would need to use something like GooglePlayServicesUtil.isGooglePlayServicesAvailable() to detect this condition and deal with it however you wish.