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DoInBackground 工作正常，加载 locals var 没有问题，但是当 doinBackground return Local[] 得到 RunTimeException 而我不知道这一点。

下面我展示了我的SupportMapFragment类实现和异常。

public class LocalMapFragment extends SupportMapFragment {

    private Local[] locals;
    private MapDrawer mapDrawer;

    public LocalMapFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        return inflater.inflate(R.layout.fragment_map_local, container, false);
    }

    @Override
    public void onActivityCreated(Bundle state) {
        super.onActivityCreated(state);

        new MapLocals(this).execute();
    }

    public void initMap(Local[] locals) {

        this.mapDrawer = new MapDrawer(this.getMap());

        this.locals = locals;

        this.mapDrawer.showLocals(this.locals);
    }

    static class MapLocals extends AsyncTask<String, Integer, Local[]> {

        LocalMapFragment localMapFragment;

        public MapLocals(LocalMapFragment localMapFragment) {

            this.localMapFragment = localMapFragment;
        }

        protected void onPreExecute() {

        }

        protected Local[] doInBackground(String... params) {

            Local[] locals = null;

            try {

                LocalService localService = new LocalService(this.localMapFragment.getActivity(),
                        "/rest/localList.json");

                locals = localService.getLocalsFromUserCity();
            } catch (Exception ex) {

                Log.e("APPERROR", ex.getMessage());
            }

            return locals;
        }

        protected void onProgressUpdate(Integer... values) {

        }

        protected void onPostExecute(Local[] locals) {

            this.localMapFragment.initMap(locals);

            /*
             * int x = 0; x = x + 2;
             * 
             * FragmentActivity activity = (FragmentActivity) this.context; if
             * (activity != null && !activity.isFinishing()) {
             * 
             * initMap(locals); }
             */
        }
    }
}

日志猫：

10-04 11:00:04.566: E/AndroidRuntime(9542): FATAL EXCEPTION: main
10-04 11:00:04.566: E/AndroidRuntime(9542): java.lang.RuntimeException: Unable to resume activity {com.myapp/com.myapp.HomeActivity}: java.lang.NullPointerException
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2760)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2216)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.app.ActivityThread.access$600(ActivityThread.java:149)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1300)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.os.Handler.dispatchMessage(Handler.java:99)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.os.Looper.loop(Looper.java:153)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.app.ActivityThread.main(ActivityThread.java:5086)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at java.lang.reflect.Method.invokeNative(Native Method)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at java.lang.reflect.Method.invoke(Method.java:511)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at dalvik.system.NativeStart.main(Native Method)
10-04 11:00:04.566: E/AndroidRuntime(9542): Caused by: java.lang.NullPointerException
10-04 11:00:04.566: E/AndroidRuntime(9542):     at maps.ag.bg.b(Unknown Source)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at bob.onTransact(SourceFile:115)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.os.Binder.transact(Binder.java:326)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at com.google.android.gms.maps.internal.IMapFragmentDelegate$a$a.onResume(Unknown Source)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at com.google.android.gms.maps.SupportMapFragment$a.onResume(Unknown Source)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at com.google.android.gms.internal.bh$6.b(Unknown Source)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at com.google.android.gms.internal.bh.a(Unknown Source)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at com.google.android.gms.internal.bh.onResume(Unknown Source)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at com.google.android.gms.maps.SupportMapFragment.onResume(Unknown Source)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.support.v4.app.Fragment.performResume(Fragment.java:1521)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:963)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1086)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.support.v4.app.FragmentManagerImpl.dispatchResume(FragmentManager.java:1887)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.support.v4.app.FragmentActivity.onResumeFragments(FragmentActivity.java:460)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.support.v4.app.FragmentActivity.onPostResume(FragmentActivity.java:449)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.app.Activity.performResume(Activity.java:5107)
10-04 11:00:04.566: E/AndroidRuntime(9542):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2718)
10-04 11:00:04.566: E/AndroidRuntime(9542):     ... 12 more
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1 回答 1

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当您尝试在其上绘制本地市场时，可能未创建您的 GoogleMap 对象。您可以在片段“onStart()”中使用此方法（来自 Google maps for Android 文档）：

    /**
     * Method to set up map. It must be called at onCreate() and onResume() to assure map has been initialized
     */
    private void setUpMapIfNeeded() {
        // Do a null check to confirm that we have not already instantiated the map.
        if (googleMap == null) {
            SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(
                    R.id.main_map);
            GoogleMap gmap = mapFragment.getMap();

            // Check if we were successful in obtaining the map.
            if (gmap != null) {
                googleMap = new GoogleMapsManager(mapFragment, getBaseContext(), this);
            }
        }
    }

当你从 AsyncTask 得到响应时，再次检查你是否已经得到了这个 googleMap 对象，然后把标记放在它上面。

于 2013-10-04T09:26:23.543 回答