Question

我试图实现地图视图，但我在log cat中收到此错误

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.****.***/com.****.***.MapView}: java.lang.NullPointerException

我的代码

public class MapView extends FragmentActivity implements LocationListener {

    private LinkedHashMap<Integer, BaseElement> info;
    private GoogleMap googleMap;
    HotelInfo hotel;
    private ProgressDialog dialog;
    private String lan, lat, name, email;
    private LatLng cameraPosition;
    private Marker[] marker;
    com.google.android.gms.maps.MapView mapView;
    private Activity activity;
    private View view;
    private ViewGroup container;
    private LayoutInflater inflater;
    private LinkedHashMap<Integer, BaseElement> hotels;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        inflater = (LayoutInflater) activity
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        view = inflater.inflate(R.layout.activity_activity_map, container,
                false);

        mapView = (com.google.android.gms.maps.MapView) view
                .findViewById(R.id.map);
        Bundle savedInstanceState2 = null;
        mapView.onCreate(savedInstanceState2);

        // Gets to GoogleMap from the MapView and does initialization stuff
        googleMap = mapView.getMap();
        googleMap.getUiSettings().setMyLocationButtonEnabled(false);
        googleMap.setMyLocationEnabled(true);

        MapsInitializer.initialize(activity);
        mapView.onResume();
        /*

}
}

我的xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:id="@+id/filmhall"
    android:background="@color/common_signin_btn_text_dark" >



  <com.google.android.gms.maps.MapView 
          android:id="@+id/map"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:layout_margin="4dp"
          android:layout_weight="1"/>  

</LinearLayout>

似乎有什么问题？当试图去这个类时应用程序崩溃。有没有办法解决这个问题？提前完成。

修改

logcat的

FATAL EXCEPTION: main
Process: com.****.***, PID: 25529
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.****.***/com.****.***.MapView}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2202)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2252)
at android.app.ActivityThread.access$800(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1200)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:606)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.fortuna.amaya.MapView.onCreate(MapView.java:56)
at android.app.Activity.performCreate(Activity.java:5275)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2166)

Answer 1

inflater = (LayoutInflater) activity
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

用

替换它

inflater = (LayoutInflater) getActivity()
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

Answer 2

在此处添加NullPointer检查：

googleMap = mapView.getMap();
if( googleMap != null ) {
    googleMap.getUiSettings().setMyLocationButtonEnabled(false);
    googleMap.setMyLocationEnabled(true);
}

检查您的申请中的上述空检查，这将阻止Exception

如果您多次犯错误，则可以切换为SupportMapFragment而不是MapView

更改：

my.xml

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

java文件：

SupportMapFragment m = ((SupportMapFragment) getActivity()
.getSupportFragmentManager().findFragmentById(R.id.mapFragment));

Answer 3

更改

inflater = (LayoutInflater) activity
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

到

 inflater = (LayoutInflater) getApplicationContext()
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
 view = inflater.inflate(R.layout.activity_activity_map, container,
            false);
 setContentView(view);

您要充气的视图必须将其设置为 setContentView 并检查googleMap - ＆gt; if（googleMap！= null）{//代码}

android mapview lava.lang.nullpointerexception

3 个答案: