MapFragment - NullPointerException异常 - 谷歌地图V2 - 机器人 [英] MapFragment - NullPointerException - Google Maps V2 - Android

问题描述

我得到一个NullPointerException异常有以下code：

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());
    }

其中NullPointerException异常是发生该生产线是该行的code：

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

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

我不初始化我MMAP变量设置为null。什么是我的问题吗？

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所创建的MapFragment。检查我的。它的工作。

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" />

...

是你的有什么不同？另外，你检查，如果你把正确的权限和元数据在AndroidManifest.xml中？

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

下面的权限：

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

和这里的元数据部分：

<application>

    ...

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

</application>

我希望这可以帮助你！

I hope this helps you!

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