Question

when i first load my app mapActivity is invoking and i can see the map, now when i
switch off the networkconnectivity and on again , changing the screen and coming back
to the mapactivity the map is showing null, getting nullpointer exception at this
line new MapUtils().drawMap(this); in onResume() method.

@Override
protected void onResume() {
    Utils utils = new Utils();
    manager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    listener = new ManageLocation();

    listener.setSucessCallBack(this, "setLocation");
    listener.setFailureCallBack(this, "setNoLocation");


    manager.requestLocationUpdates(
            utils.getCurrentPlaceLocationProvider(manager), 0, 0,
            listener);
    super.onResume();

    Log.d(TAG, "Constants.isDataLoadedPAB " + Constants.isMaptobeLoaded
            + " Constants.isDataLoadedPAB : " + Constants.isDataLoadedPAB);
    if (Constants.isMaptobeLoaded) {
        if (Constants.isDataLoadedPAB) {
            try {
                new MapUtils().drawMap(this);
            } catch (Exception e) {
                Log.e(TAG, "Error", e);
            }
        } else {
            if (Constants.currentLocation != null
                    && Constants.searchLocation != null) {
                if (Constants.searchResultData == null) {
                    Constants.searchResultData = new ArrayList<AttractionData>();
                }

                new MapUtils().drawMap(this);

            }
            }
    }
    ((ImageView) activity.findViewById(R.id.left)).setEnabled(true);
    ((ImageView) activity.findViewById(R.id.right)).setEnabled(true);   
    ((ImageView) findViewById(R.id.searchicon)).setEnabled(true);

    ((ImageView) activity.findViewById(R.id.facebookintegration)).setEnabled(true);
}

I am trying to invoke it again in onResume() but still getting null.
i am struck not sure where i am doing wrong.Any help is appreciated

my log

01-29 11:23:36.325: E/AndroidRuntime(6668): Caused by: java.lang.NullPointerException
01-29 11:23:36.325: E/AndroidRuntime(6668):     at org.appright.myneighborhood.maps.MapUtils.drawMap(MapUtils.java:59)
01-29 11:23:36.325: E/AndroidRuntime(6668):     at org.appright.myneighborhood.activity.CityAttractions.onResume(CityAttractions.java:505)
01-29 11:23:36.325: E/AndroidRuntime(6668):     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1199)
01-29 11:23:36.325: E/AndroidRuntime(6668):     at android.app.Activity.performResume(Activity.java:5280)
01-29 11:23:36.325: E/AndroidRuntime(6668):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2606)
01-29 11:23:36.325: E/AndroidRuntime(6668):     ... 10 more

Answer 1

The problem is with this line

FrameLayout topLayout = (FrameLayout) activity.findViewById(R.id.map_container);
                    topLayout.removeAllViews();

in MapUtils().drawMap(this);

what you are doing is to remove all the view from container i.e. FrameLayout map_container
when network connection not available.

And when network comes again you are accessing the MapView which you have removed from the layout hierarchy and it wont find the defaultmapView this time and throw NullPionterException.

Try to comment all the code in else block and just show a toast only. hope it will work. Or try some different logic.