Question

my activity with a mapview crashes out randomly. I think all my potentially null variables are handled but one out of 10 times, they are not. I’ve attached my activity and the error below.

public class HomeActivity extends MapActivity {

boolean pickup = false;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.home);

    findViewById(R.id.searchBar).setVisibility(View.VISIBLE);

    findViewById(R.id.searchBar).setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

            //load new dialog thing with only a onSearchRequested() thing, and a bg click that finishes the app

            //but also somehow returns the result back to the map??? put intent, here get intent on resume()?? or whatever, debug breakpoints
            findViewById(R.id.searchBar).setVisibility(View.GONE);

            Intent pseudoSearch = new Intent(HomeGroup.group, PseudoMapSearchActivity.class);
            startActivityForResult(pseudoSearch, 0);
        }

    });

    // initialize the map and set the default location
    MapView map = (MapView) findViewById(R.id.map);
    //map.setBuiltInZoomControls(true);
    map.setSatellite(false);


    MapController controller = map.getController();
    List<Overlay> overlays = map.getOverlays();

    Drawable drawable = this.getResources().getDrawable(
            R.drawable.origin_pin);
    HomeItemizedOverlay overlay = new HomeItemizedOverlay(drawable,
            HomeGroup.group);


    overlays.clear();
    overlays.add(overlay);

    controller.setZoom(17);
    map.postInvalidate();

    final LocationManager locator = (LocationManager) this
            .getSystemService(Context.LOCATION_SERVICE);
    String provider = "";

    // check what location provider is available
    if (!locator.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
        //provider = LocationManager.GPS_PROVIDER;

        //force user to turn on gps
        Criteria criteria = new Criteria();
        criteria.setAccuracy(Criteria.ACCURACY_FINE);
        criteria.setPowerRequirement(Criteria.POWER_HIGH);

        LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
        provider = lm.getBestProvider(criteria, true);
    } else {
        provider = LocationManager.GPS_PROVIDER;
    }

    // get the current location
    if (provider != null) {
        //setLocation(locator.getLastKnownLocation(provider));

        final LocationListener listener = new LocationListener() {

            @Override
            public void onLocationChanged(Location location) {
                setLocation(location);
                locator.removeUpdates(this);
            }

            @Override
            public void onProviderDisabled(String provider) {
            }

            @Override
            public void onProviderEnabled(String provider) {
            }

            @Override
            public void onStatusChanged(String provider, int status,
                    Bundle extras) {
            }
        };

        locator.requestLocationUpdates(provider, 15000, 0, listener);
    } else {
        Toast toast = Toast.makeText(HomeActivity.this,
                "Location provider could not be found.", Toast.LENGTH_LONG);
        toast.show();
    }

}

/**
 * Performs any action required to update the current location displayed on
 * the home map.
 * 
 * @param location
 *            A {@link Location} object with the new location to display.
 */
private void setLocation(Location location) {

    if (location == null) {
        return;
    }

    if(AndroidHelper.pickup == false)
    {
        MapView map = (MapView) findViewById(R.id.map);
        map.setSatellite(false);

        MapController controller = map.getController();
        List<Overlay> overlays = map.getOverlays();

        Drawable drawable = this.getResources().getDrawable(
            R.drawable.origin_pin);
        HomeItemizedOverlay overlay = new HomeItemizedOverlay(drawable,
            HomeGroup.group);

        int latitude = (int) (location.getLatitude() * 1e6);
        int longitude = (int) (location.getLongitude() * 1e6);

        GeoPoint point = new GeoPoint(latitude, longitude);
        if(point!=null)
        {   
            OverlayItem item = new OverlayItem(point, "Current Location",
                    "This is where you are currently located.");
            overlay.setOrigin(item);
        }
        overlays.clear();
        overlays.add(overlay);

        controller.animateTo(point);
        controller.setZoom(18);
        map.postInvalidate();
    }



}

here is my HomeItemizedOverlay class

 public class HomeItemizedOverlay extends ItemizedOverlay<OverlayItem> {

    private Map<Integer, OverlayItem> overlays = null;
    private Context context = null;

    private static final int ORIGIN = 0;
    private static final int DESTINATION = 1;

    public HomeItemizedOverlay(Drawable defaultMarker) {
            super(boundCenterBottom(defaultMarker));
            this.overlays = new HashMap<Integer, OverlayItem>();
    }

    public HomeItemizedOverlay(Drawable defaultMarker, Context context) {
            this(defaultMarker);
            this.context = context;
    }

    /**
     * Set an {@link OverlayItem} to be the origin and calls {@link #populate()}
     * to create the overlay.
     * 
     * @param item
     *            An item to add to the overlay.
     */
    public void setOrigin(OverlayItem item) {
            this.overlays.put(ORIGIN, item);
            populate();
    }

    /**
     * Adds an {@link OverlayItem} to be the destination and calls
     * {@link #populate()} to create the overlay.
     * 
     * @param item
     *            An item to add to the overlay.
     */
    public void setDestination(OverlayItem item) {
            this.overlays.put(DESTINATION, item);
            populate();
    }

    @Override
    protected OverlayItem createItem(int i) {
            return this.overlays.get(i);
    }

    @Override
    public int size() {
            return this.overlays.size();
    }

    @Override
    protected boolean onTap(int index) {
            OverlayItem item = this.overlays.get(index);

            //think this causes crashes
            AlertDialog.Builder dialog = new AlertDialog.Builder(this.context);
            dialog.setTitle(item.getTitle());
            dialog.setMessage(item.getSnippet());
            dialog.show();

            return true;
    }
}

this logcat error does not mention a line in my code, so I don’t really understand where it is breaking. This happens about 1 out of 10 times.

11-15 13:47:13.192: E/AndroidRuntime(3585): FATAL EXCEPTION: main
11-15 13:47:13.192: E/AndroidRuntime(3585): java.lang.NullPointerException
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.google.android.maps.ItemizedOverlay.getItemsAtLocation(ItemizedOverlay.java:617)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.google.android.maps.ItemizedOverlay.getItemAtLocation(ItemizedOverlay.java:586)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.google.android.maps.ItemizedOverlay.handleMotionEvent(ItemizedOverlay.java:498)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.google.android.maps.ItemizedOverlay.onTouchEvent(ItemizedOverlay.java:572)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.google.android.maps.OverlayBundle.onTouchEvent(OverlayBundle.java:63)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.google.android.maps.MapView.onTouchEvent(MapView.java:679)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.View.dispatchTouchEvent(View.java:3882)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:903)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1691)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1125)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.app.Activity.dispatchTouchEvent(Activity.java:2096)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1691)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1125)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.app.Activity.dispatchTouchEvent(Activity.java:2096)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1691)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1125)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.app.Activity.dispatchTouchEvent(Activity.java:2096)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2204)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1888)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.os.Looper.loop(Looper.java:130)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at android.app.ActivityThread.main(ActivityThread.java:3683)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at java.lang.reflect.Method.invokeNative(Native Method)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at java.lang.reflect.Method.invoke(Method.java:507)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-15 13:47:13.192: E/AndroidRuntime(3585):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

Try calling populate() immediately after you call super in your constructor. There have been other complaints of problems like this http://code.google.com/p/android/issues/detail?id=2035.

The javadoc for populate says:

Utility method to perform all processing on a new ItemizedOverlay. Subclasses provide Items through the createItem(int) method. The subclass should call this as soon as it has data, before anything else gets called.

which honestly isn’t very helpful, but I believe you have to call this method in your constructor.