Question

我正在关注此tutorial以根据用户的位置设置Google地图和标记。但是，我得到了这个运行时空指针异常。任何人都可以帮我看看提供此代码的问题：

public class MapsActivity extends FragmentActivity implements
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,
        LocationListener {

    public static final String TAG = MapsActivity.class.getSimpleName();

    private static final long UPDATE_INTERVAL = 5000;
    private static final long FASTEST_INTERVAL = 1000;
    private static final int CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;

    private TextView mOutput;
    private ScrollView mScroller;

    private long mLastTime;

    private GoogleApiClient mGoogleApiClient;
    private LocationRequest mLocationRequest;

    private static final LatLng MOOREA = new LatLng(-17.506621, -149.821926);
    private GoogleMap map;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        setUpMapIfNeeded();

        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();

        // Create the LocationRequest object
        mLocationRequest = LocationRequest.create()
                .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
                .setInterval(10 * 1000)        // 10 seconds, in milliseconds
                .setFastestInterval(1 * 1000); // 1 second, in milliseconds

        /*if (mMap != null){
            mMap.setMyLocationEnabled(true);
            mMap.setMapType(GoogleMap.MAP_TYPE_TERRAIN);
        }

        Criteria criteria = new Criteria();
        LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        String provider = locationManager.getBestProvider(criteria, false);
        Location location = locationManager.getLastKnownLocation(provider);
        double lat =  location.getLatitude();
        double lng = location.getLongitude();
        LatLng coordinate = new LatLng(lat, lng);*/


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

        //Marker moorea = map.addMarker(new MarkerOptions().position(MOOREA).title("Paopao, Moorea").snippet("Polynésie Francaise"));

        // zoom in the camera to Moorea
        //map.moveCamera(CameraUpdateFactory.newLatLngZoom(MOOREA, 5));

        // animate the zoom process
        //map.animateCamera(CameraUpdateFactory.zoomTo(15), 2000, null);
    }

    @Override
    protected void onResume() {
        super.onResume();
        setUpMapIfNeeded();
        mGoogleApiClient.connect();
    }

    @Override
    protected void onPause() {
        super.onPause();

        if (mGoogleApiClient.isConnected()) {
            LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
            mGoogleApiClient.disconnect();
        }
    }

    @Override
    public void onConnected(Bundle bundle) {

    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onLocationChanged(Location location) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {

    }

    private void setUpMapIfNeeded() {
        // Do a null check to confirm that we have not already instantiated the map.
        if (map == null) {
            // Try to obtain the map from the SupportMapFragment.
            map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.mapView))
                    .getMap();
            // Check if we were successful in obtaining the map.
            if (map != null) {
                setUpMap();
            }
        }
    }

    private void setUpMap() {
        map.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
    }
}

我有这样的activity_maps.xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:map="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MapsActivity">

    <fragment
        android:id="@+id/mapView"
        class="com.google.android.gms.maps.MapFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        map:mapType="hybrid"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        map:uiZoomControls="false"
        />

</RelativeLayout>

logcat的：

07-26 23:18:26.304  21185-21185/org.example.vaamap E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{org.example.vaamap/org.example.vaamap.MapsActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2092)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2117)
            at android.app.ActivityThread.access$700(ActivityThread.java:134)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1218)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4867)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1007)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:774)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at org.example.vaamap.MapsActivity.setUpMapIfNeeded(MapsActivity.java:147)
            at org.example.vaamap.MapsActivity.onCreate(MapsActivity.java:66)
            at android.app.Activity.performCreate(Activity.java:5047)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2056)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2117)
            at android.app.ActivityThread.access$700(ActivityThread.java:134)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1218)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4867)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1007)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:774)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

更改xml片段映射并删除类行

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

Android的位置服务测试：空指针异常

1 个答案: