android - getMap() 函数出错

Question

我只是创建一个 map 项目并执行此代码。但是有 getMap() 错误。我尝试了一些来自互联网的示例代码，但 getMap() 函数中也存在同样的错误。代码是:

    private GoogleMap mMap;
    static final LatLng TutorialsPoint = new LatLng(21 , 57);
     @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);


    if (mMap == null) {
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);

    try {
        if (mMap == null) {

                   mMap = ((MapFragment) getFragmentManager().
                   findFragmentById(R.id.map)).getMap();
                    //findFragmentById(R.id.map)).getMap();
        }
        mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
        Marker TP = mMap.addMarker(new MarkerOptions().
                position(TutorialsPoint).title("TutorialsPoint"));
    }
    catch (Exception e) {
        e.printStackTrace();
    }
}




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

    // Add a marker in Sydney and move the camera
    LatLng sydney = new LatLng(-34, 151);
    mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
}

这是我的 Android list 文件。

 <?xml version="1.0" encoding="utf-8"?>
  <manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.priya.finalproject">

<!--
     The ACCESS_COARSE/FINE_LOCATION permissions are not required to use
     Google Maps Android API v2, but you must specify either coarse or fine
     location permissions for the 'MyLocation' functionality. 
-->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">

    <!--
         The API key for Google Maps-based APIs is defined as a string resource.
         (See the file "res/values/google_maps_api.xml").
         Note that the API key is linked to the encryption key used to sign the APK.
         You need a different API key for each encryption key, including the release key that is used to
         sign the APK for publishing.
         You can define the keys for the debug and release targets in src/debug/ and src/release/.
    -->
    <meta-data
        android:name="com.google.android.maps.v2.API_KEY"
        android:value="AIzaSyCBp-ide4ue3DKt-tud4SdzwzR652OSnGY" />
    <!--  <meta-data
         android:name="com.google.android.geo.API_KEY"
         android:value="@string/google_maps_key" />-->

     <activity
         android:name=".MapsActivity"
         android:label="@string/title_activity_maps">
         <intent-filter>
             <action android:name="android.intent.action.MAIN" />

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

Answer 1

当 onMapReady 函数被触发时，您应该将标记添加到您的 map 中，这发生在您的 map 准备好使用时(例如添加标记等)。只需初始化您的 map 并调用 getMapAsync 功能类似

    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this); 

使用 googleMap 对象来操作您在 onMapReady 中提供给您的 map 。