更新的
我读了很多主题,但没有帮助或我不知道该怎么做。我失去了我不知道为什么。我只是在学习,所以请帮帮我。

java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.SupportMapFragment.getMapAsync(com.google.android.gms.maps.OnMapReadyCallback)' on a null object reference
        at com.example.text.fragments.MapFragment.initilizeMap(MapFragment.java:52)
        at com.example.text.fragments.MapFragment.onViewCreated(MapFragment.java:46)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:971)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1136)
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1499)
        at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:488)
        at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:163)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1073)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:919)
        at android.support.v4.view.ViewPager$3.run(ViewPager.java:249)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:792)
        at android.view.Choreographer.doCallbacks(Choreographer.java:596)
        at android.view.Choreographer.doFrame(Choreographer.java:556)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:778)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:155)
        at android.app.ActivityThread.main(ActivityThread.java:5696)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1028)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)

这是我实现getmap的片段
public class MapFragment extends Fragment implements OnMapReadyCallback{

    private GoogleMap googleMap;
    /**
     * function to load map. If map is not created it will create it for you
     * */


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.map_fragment, container, false);
        return view;
    }
    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onViewCreated(view, savedInstanceState);
        // here, as doc say, the map can be initialized, or the service is not available
        initilizeMap();
    }

     private void initilizeMap() {
        if (googleMap == null) {
            ((SupportMapFragment) getActivity().getSupportFragmentManager().findFragmentById(
                    R.id.map)).getMapAsync(this);

            // check if map is created successfully or not
            if (googleMap == null) {
                Toast.makeText(getActivity().getApplicationContext(),
                        "Sorry! unable to create maps", Toast.LENGTH_SHORT)
                        .show();
            }
        }
    }

    @Override
    public void onMapReady(GoogleMap mGoogleMap) {
        googleMap = mGoogleMap;
    }
}

这是map_fragment.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

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


</RelativeLayout>

这是我的名单
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.test" >

    <permission
        android:name="com.example.test.permission.MAPS_RECEIVE"
        android:protectionLevel="signature" />

    <uses-permission android:name="com.example.test.permission.MAPS_RECEIVE" />

    <uses-sdk
        android:minSdkVersion="17"
        android:targetSdkVersion="22" />

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

    <!-- Required to show current location -->
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

    <!-- Required OpenGL ES 2.0. for Maps V2 -->
    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme"
        android:supportsRtl="true">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <meta-data
            android:name="com.google.android.maps.v2.API_KEY"
            android:value="AIzaSyBUeq6ANw9MyK9vwB4phnSOkp6e_UccN4E" />

    </application>

</manifest>

我使用滑动标签,在一个标签必须有地图。我在viewpageradapter中的代码的这一部分创建了这个地图:
 @Override
    public Fragment getItem(int position) {

        if(mNumbOfTabs == 3) {
            if (position == 0) {
                A a = new A();
                return a;
            } else if (position == 1) {
                B b = new B();
                return b;
            } else {
                MapFragment mapFragment = new MapFragment();
                return mapFragment;
            }
    }

最佳答案

因为6.5版本的play服务googlerecommends using of asynchronous getting of GoogleMapgetMap()现在已经被弃用。正如stkent所提到的,你必须打电话给getMapAsync(this)
由于此方法是异步的,因此需要对此方法进行回调,这就是为什么还必须使片段实现OnMapReadyCallback,并且在这些回调的onMapReady()方法中,可以获得对映射的引用。
同时将行((SupportMapFragment)getActivity().getSupportFragmentManager().findFragmentById(R.id.map)).getMapAsync(this);更改为((SupportMapFragment)getChildFragmentManager().findFragmentById(R.id.map)).getMapAsync(this);,因为在片段内部必须使用childfragmentmanager。

关于android - Google Maps getMap返回null,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/30077101/

10-11 01:09