MapFragment - NullPointerException - Google Maps V2 - Android [英] MapFragment - NullPointerException - Google Maps V2 - Android

问题描述

我收到一个带有以下代码的 NullPointerException:

I'm getting an NullPointerException with the following code:

private ProjectionProxy proxy = new ProjectionProxy();
private GoogleMap mMap = null;
private Context context = this;

@Override
protected void onCreate(Bundle load) { 
    super.onCreate(load);

    setContentView(R.layout.fragment_ride_tracking);

    //mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.myMapView)).getMap();

    mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();

    int result = GooglePlayServicesUtil.isGooglePlayServicesAvailable(context);

    mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
    mMap.setMyLocationEnabled(true);

    //SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.myMapView);
    //mMap = mapFragment.getMap();

    Log.e("RideTracking", "Google Map VALUE:"+mMap);

    if (mMap != null) { 
        proxy.setProjection(mMap.getProjection());
    }

发生 NullPointerException 的那一行是这行代码:

The line where the NullPointerException is happening is this line of code:

mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();

我没有将我的 mMap 变量初始化为 null.我的问题是什么?

I'm not initializing my mMap variable to null. What is my issue here?

推荐答案

尝试检查您在活动的 XML 中创建的 MapFragment.检查我的；它正在工作.

Try to check the MapFragment that you've created in the XML of the Activity. Check mine; it's working.

...

<fragment
        android:id="@+id/map"
        android:name="com.google.android.gms.maps.MapFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

...

你的不一样吗?此外，您是否检查过是否在 AndroidManifest.xml 上放置了正确的权限和元数据?

Is yours different? Also, you checked if you put the correct permissions and metadata on the AndroidManifest.xml?

权限如下:

<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />

这里是元数据部分:

<application>

    ...

    <meta-data android:name="com.google.android.maps.v2.API_KEY"
               android:value="HERE GOES YOUR API KEY" />

</application>

希望对你有帮助！

这篇关于MapFragment - NullPointerException - Google Maps V2 - Android的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！