Question

我想在静态cardview中放置一个谷歌地图，其他元素如按钮，textview等。

所以我创建了这个xml：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/prenotation"
>

<android.support.v7.widget.CardView
    android:id="@+id/card_view"
    android:layout_width="fill_parent"
    android:layout_height="match_parent"
    android:layout_margin="5dp"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center_horizontal|bottom">

        <com.google.android.gms.maps.MapView
            android:id="@+id/map"
            android:layout_width="match_parent"
            android:layout_height="160dp"
            android:enabled="true" />


    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="LIMB"
        android:textColor="#000"
        android:textSize="30dp"
        android:id="@+id/and"
        android:layout_marginTop="40dp"
        android:layout_below="@+id/map"
        android:layout_alignLeft="@+id/view1"
        android:layout_alignStart="@+id/view1"
        android:layout_marginLeft="30dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="LIPU"
        android:textColor="#000"
        android:textSize="30dp"
        android:id="@+id/rit"
        android:layout_alignTop="@+id/and"
        android:layout_alignRight="@+id/view1"
        android:layout_alignEnd="@+id/view1"
        android:layout_marginRight="30dp"
        android:layout_marginEnd="30dp" />
 </RelativeLayout>
</android.support.v7.widget.CardView>

这在Java中：

   public class PrenotationFragment extends Fragment
   {
    String objID;
    MapView mMapView;
    GoogleMap mgoogleMap;

    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState)
    {
        View rootView = inflater.inflate(R.layout.fragment_prenotation, container, false);
        Bundle args = getArguments();
        Button prenota = (Button)rootView.findViewById(R.id.prenotate);
        if(args != null)
        {
            objID = args.getString("Obj");

            Download task = new Download(objID,getActivity(),rootView);
            task.execute();

        }
        prenota.setOnClickListener(new View.OnClickListener()
        {
            public void onClick(View v)
            {
                String url = "http://www.aviosharing.eu/?flight=("+objID+")";
                Intent i = new Intent(Intent.ACTION_VIEW);
                i.setData(Uri.parse(url));
                startActivity(i);
            }
        });

        mMapView = (MapView) rootView.findViewById(R.id.map);
        mMapView.onCreate(savedInstanceState);
        mMapView.onResume();// needed to get the map to display immediately
        try
        {
            MapsInitializer.initialize(getActivity().getApplicationContext());
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

        mMapView.getMapAsync(new OnMapReadyCallback()
        {

            public void onMapReady(GoogleMap googleMap)
            {
                mgoogleMap = googleMap;
            }
        });
        return rootView;
    }
       public void onResume() {
        super.onResume();
        mMapView.onResume();
    }
    public void onPause() {
        super.onPause();
        mMapView.onPause();
    }
    public void onLowMemory() {
        super.onLowMemory();
        mMapView.onLowMemory();
    }
    public void onDestroy() {
        super.onDestroy();
        mMapView.onDestroy();
    }
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        mMapView.onSaveInstanceState(outState);
    }

但是当我加载它时，我收到此错误消息：

java.lang.NullPointerException：尝试调用虚方法＆＃39; void com.google.android.gms.maps.MapView.onCreate（android.os.Bundle）＆＃39;在...上 null对象引用在 com.example.carsharing.PrenotationFragment.onCreateView（PrenotationFragment.java:79）在 android.support.v4.app.Fragment.performCreateView（Fragment.java:1974）在 android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1067）在 android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1252）在 android.support.v4.app.BackStackRecord.run（BackStackRecord.java:742）在 android.support.v4.app.FragmentManagerImpl.execPendingActions（FragmentManager.java:1617）在 android.support.v4.app.FragmentManagerImpl $ 1.run（FragmentManager.java:517）在android.os.Handler.handleCallback（Handler.java:739）在android.os.Handler.dispatchMessage（Handler.java:95）在android.os.Looper.loop（Looper.java:135）在android.app.ActivityThread.main（ActivityThread.java:5253） at java.lang.reflect.Method.invoke（Native Method）在java.lang.reflect.Method.invoke（Method.java:372）在 com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:899）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:694）

为什么我收到此错误？我想也是，我需要使用：

   <fragment
    android:id="@+id/map"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    class="com.google.android.gms.maps.MapFragment" />

在这种情况下，

而不是MapView？

由于

谷歌地图不起作用... mapView或片段地图？

0 个答案: