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嘿,我是 android 新手,我正在处理一个面向地图的项目,现在我在触摸覆盖项目时遇到问题,它在 log-cat 中显示空指针异常,我不明白这是什么意思。这里我有两个类MyPlacemapActivity 和 AddItemizedOverlay 有人请帮我解决这个问题,这是我的课程代码

AddItemizedOverlay.java

public class AddItemizedOverlay extends ItemizedOverlay<OverlayItem> {

       private ArrayList<OverlayItem> mapOverlays = new ArrayList<OverlayItem>();

       private Context context;
       String reference;
       private String username;

       String p_u_name;
       public AddItemizedOverlay(Drawable defaultMarker) {
            super(boundCenterBottom(defaultMarker));
       }

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

       public AddItemizedOverlay(Drawable defaultMarker, Context context,String StringData) {
                   this(defaultMarker);
                   this.context = context;
       this.username=StringData;
       System.out.println("AdditemizedOverlay:got username:"+username +StringData);
              }


       @Override
       public boolean onTouchEvent(MotionEvent event, MapView mapView)
       {   
               if (event.getAction() == 1) {
               GeoPoint geopoint = mapView.getProjection().fromPixels(
                   (int) event.getX(),
                   (int) event.getY());
           }
           return false;
       } 

       @Override
       protected OverlayItem createItem(int i) {
          return mapOverlays.get(i);
       }
       @Override
       public int size() {
          return mapOverlays.size();
       }

      @Override
       protected boolean onTap(int index) {
         OverlayItem item = mapOverlays.get(index);
         AlertDialog.Builder dialog = new AlertDialog.Builder(this.context);
         reference = item.getSnippet();
         username =  item.getTitle();
         dialog.setTitle("");
         dialog.setMessage("Do you want ot park here ?");
         System.out.println("Inside Additemized:"+reference+username);
         dialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {


                SharedPreferences prefs = context.getSharedPreferences("myprefs", 0);
                SharedPreferences.Editor editor =prefs.edit();
                editor.putString("KEY_REFERENCE", reference);
                editor.putString("KEY_USERNAME", username);
                editor.commit();                

                Intent intent = new Intent(context, SinglePlaceActivity.class);
                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                context.startActivity(intent);
            }
         })
            .setNegativeButton("No",new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog,int id) {
                    // if this button is clicked, just close
                    // the dialog box and do nothing
                    dialog.cancel();
//                  MainActivity.this.finish();
                }
            });
         dialog.show();
         return true;
       }

       public void addOverlay(OverlayItem overlay) {
          mapOverlays.add(overlay);
       }

       public void populateNow(){
           this.populate();
       }

    }

MyPlacemapActivity.java

public class MyPlacemapActivity extends MapActivity {
    // Nearest places
    PlacesList nearPlaces;

    // Map view
    MapView mapView;

    // Map overlay items
    List<Overlay> mapOverlays;

    AddItemizedOverlay itemizedOverlay;
    MyItemizedOverlay myitemizedoverlay;
    FindItemizedOverlay finditemizedoverlay;

    GeoPoint geoPoint;
    // Map controllers
    MapController mc;

    Drawable defaultMarker,drawable;

    double latitude;
    double longitude;
    OverlayItem overlayitem;

    String p_u_name;
    String type,keyword;

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

        SharedPreferences prefs = getSharedPreferences("myprefs", 0);
        p_u_name = prefs.getString("KEY_USERNAME", "");

        Intent i = getIntent();

        // Users current geo location
        String user_latitude = i.getStringExtra("user_latitude");
        String user_longitude = i.getStringExtra("user_longitude");
        type = i.getExtras().getString("KEY_TYPES");
        keyword =i.getExtras().getString("KEY_KEYWORD");

        System.out.println("sarath"+user_latitude + user_longitude + type);

        // Nearplaces list
        nearPlaces = (PlacesList) i.getSerializableExtra("near_places");

        mapView = (MapView) findViewById(R.id.mapView);
        mapView.setBuiltInZoomControls(true);

        mapOverlays = mapView.getOverlays();

        // Geopoint to place on map
        geoPoint = new GeoPoint((int) (Double.parseDouble(user_latitude) * 1E6),(int) (Double.parseDouble(user_longitude) * 1E6));

        // Drawable marker icon
        Drawable drawable_user = this.getResources().getDrawable(R.drawable.mark_red);

        myitemizedoverlay = new MyItemizedOverlay(drawable_user, this);

        // Map overlay item
        overlayitem = new OverlayItem(geoPoint, "Your Location","That is you!");

        myitemizedoverlay.addOverlay(overlayitem);

        mapOverlays.add(myitemizedoverlay);
        myitemizedoverlay.populateNow();

        System.out.println("keyword:"+keyword+"type:"+type);
//----------------------------------------------------------------------------------------------------------        
        // Drawable marker icon
        if(type.equalsIgnoreCase("gas_station")&&keyword.equalsIgnoreCase("gas_station")){
             drawable= this.getResources().getDrawable(R.drawable.mark_gasstation);
             finditemizedoverlay = new FindItemizedOverlay(drawable);

        mc = mapView.getController();

        // These values are used to get map boundary area
        // The area where you can see all the markers on screen
        int minLat = Integer.MAX_VALUE;
        int minLong = Integer.MAX_VALUE;
        int maxLat = Integer.MIN_VALUE;
        int maxLong = Integer.MIN_VALUE;

        // check for null in case it is null
        if (nearPlaces.results != null) {


            // loop through all the places
            for (Place mplace : nearPlaces.results) {

                latitude = mplace.geometry.location.lat; // latitude
                longitude = mplace.geometry.location.lng; // longitude

                // Geopoint to place on map
                geoPoint = new GeoPoint((int) (latitude * 1E6),
                        (int) (longitude * 1E6));

                // Map overlay item
                overlayitem = new OverlayItem(geoPoint,p_u_name,mplace.reference);

                finditemizedoverlay.addOverlay(overlayitem);

                // calculating map boundary area
                minLat  = (int) Math.min( geoPoint.getLatitudeE6(), minLat );
                minLong = (int) Math.min( geoPoint.getLongitudeE6(), minLong);
                maxLat  = (int) Math.max( geoPoint.getLatitudeE6(), maxLat );
                maxLong = (int) Math.max( geoPoint.getLongitudeE6(), maxLong );
            }
            mapOverlays.add(finditemizedoverlay);

            // showing all overlay items
            finditemizedoverlay.populateNow();
        }


        // Adjusting the zoom level so that you can see all the markers on map
        mapView.getController().zoomToSpan(Math.abs( minLat - maxLat ), Math.abs( minLong - maxLong ));

        // Showing the center of the map
        mc.animateTo(new GeoPoint((maxLat + minLat)/2, (maxLong + minLong)/2 ));
        mapView.postInvalidate();
        }

        else if(type.equalsIgnoreCase("shopping_mall")&&keyword.equalsIgnoreCase("shopping_mall")){
            drawable= this.getResources().getDrawable(R.drawable.mark_shopping);
             finditemizedoverlay = new FindItemizedOverlay(drawable);

        mc = mapView.getController();

        // These values are used to get map boundary area
        // The area where you can see all the markers on screen
        int minLat = Integer.MAX_VALUE;
        int minLong = Integer.MAX_VALUE;
        int maxLat = Integer.MIN_VALUE;
        int maxLong = Integer.MIN_VALUE;

        // check for null in case it is null
        if (nearPlaces.results != null) {


            // loop through all the places
            for (Place mplace : nearPlaces.results) {

                latitude = mplace.geometry.location.lat; // latitude
                longitude = mplace.geometry.location.lng; // longitude

                // Geopoint to place on map
                geoPoint = new GeoPoint((int) (latitude * 1E6),
                        (int) (longitude * 1E6));

                // Map overlay item
                overlayitem = new OverlayItem(geoPoint,p_u_name,mplace.reference);

                finditemizedoverlay.addOverlay(overlayitem);

                // calculating map boundary area
                minLat  = (int) Math.min( geoPoint.getLatitudeE6(), minLat );
                minLong = (int) Math.min( geoPoint.getLongitudeE6(), minLong);
                maxLat  = (int) Math.max( geoPoint.getLatitudeE6(), maxLat );
                maxLong = (int) Math.max( geoPoint.getLongitudeE6(), maxLong );
            }
            mapOverlays.add(finditemizedoverlay);

            // showing all overlay items
            finditemizedoverlay.populateNow();
        }


        // Adjusting the zoom level so that you can see all the markers on map
        mapView.getController().zoomToSpan(Math.abs( minLat - maxLat ), Math.abs( minLong - maxLong ));

        // Showing the center of the map
        mc.animateTo(new GeoPoint((maxLat + minLat)/2, (maxLong + minLong)/2 ));
        mapView.postInvalidate();
        }

    else if(type.equalsIgnoreCase("restaurant")&&keyword.equalsIgnoreCase("restaurant")){
        drawable= this.getResources().getDrawable(R.drawable.mark_restaurant_blue);
         finditemizedoverlay = new FindItemizedOverlay(drawable);

    mc = mapView.getController();

    // These values are used to get map boundary area
    // The area where you can see all the markers on screen
    int minLat = Integer.MAX_VALUE;
    int minLong = Integer.MAX_VALUE;
    int maxLat = Integer.MIN_VALUE;
    int maxLong = Integer.MIN_VALUE;

    // check for null in case it is null
    if (nearPlaces.results != null) {


        // loop through all the places
        for (Place mplace : nearPlaces.results) {

            latitude = mplace.geometry.location.lat; // latitude
            longitude = mplace.geometry.location.lng; // longitude

            // Geopoint to place on map
            geoPoint = new GeoPoint((int) (latitude * 1E6),
                    (int) (longitude * 1E6));

            // Map overlay item
            overlayitem = new OverlayItem(geoPoint,p_u_name,mplace.reference);

            finditemizedoverlay.addOverlay(overlayitem);

            // calculating map boundary area
            minLat  = (int) Math.min( geoPoint.getLatitudeE6(), minLat );
            minLong = (int) Math.min( geoPoint.getLongitudeE6(), minLong);
            maxLat  = (int) Math.max( geoPoint.getLatitudeE6(), maxLat );
            maxLong = (int) Math.max( geoPoint.getLongitudeE6(), maxLong );
        }
        mapOverlays.add(finditemizedoverlay);

        // showing all overlay items
        finditemizedoverlay.populateNow();
    }


    // Adjusting the zoom level so that you can see all the markers on map
    mapView.getController().zoomToSpan(Math.abs( minLat - maxLat ), Math.abs( minLong - maxLong ));

    // Showing the center of the map
    mc.animateTo(new GeoPoint((maxLat + minLat)/2, (maxLong + minLong)/2 ));
    mapView.postInvalidate();
    }

    else if(type.equalsIgnoreCase("parking")&&keyword.equalsIgnoreCase("garage parking")){
        drawable= this.getResources().getDrawable(R.drawable.mark_blue);
         itemizedOverlay = new AddItemizedOverlay(drawable);

    mc = mapView.getController();

    // These values are used to get map boundary area
    // The area where you can see all the markers on screen
    int minLat = Integer.MAX_VALUE;
    int minLong = Integer.MAX_VALUE;
    int maxLat = Integer.MIN_VALUE;
    int maxLong = Integer.MIN_VALUE;

    // check for null in case it is null
    if (nearPlaces.results != null) {


        // loop through all the places
        for (Place mplace : nearPlaces.results) {

            latitude = mplace.geometry.location.lat; // latitude
            longitude = mplace.geometry.location.lng; // longitude

            // Geopoint to place on map
            geoPoint = new GeoPoint((int) (latitude * 1E6),
                    (int) (longitude * 1E6));

            // Map overlay item
            overlayitem = new OverlayItem(geoPoint,p_u_name,mplace.reference);

            System.out.println("inside mymap:"+mplace.reference+p_u_name);

            itemizedOverlay.addOverlay(overlayitem);

            // calculating map boundary area
            minLat  = (int) Math.min( geoPoint.getLatitudeE6(), minLat );
            minLong = (int) Math.min( geoPoint.getLongitudeE6(), minLong);
            maxLat  = (int) Math.max( geoPoint.getLatitudeE6(), maxLat );
            maxLong = (int) Math.max( geoPoint.getLongitudeE6(), maxLong );
        }
        mapOverlays.add(itemizedOverlay);

        // showing all overlay items
        itemizedOverlay.populateNow();
    }


    // Adjusting the zoom level so that you can see all the markers on map
    mapView.getController().zoomToSpan(Math.abs( minLat - maxLat ), Math.abs( minLong - maxLong ));

    // Showing the center of the map
    mc.animateTo(new GeoPoint((maxLat + minLat)/2, (maxLong + minLong)/2 ));
    mapView.postInvalidate();
    }
    else if(type.equalsIgnoreCase("parking")&&keyword.equalsIgnoreCase("street parking")){
        drawable= this.getResources().getDrawable(R.drawable.mark_blue);
         itemizedOverlay = new AddItemizedOverlay(drawable);

    mc = mapView.getController();

    // These values are used to get map boundary area
    // The area where you can see all the markers on screen
    int minLat = Integer.MAX_VALUE;
    int minLong = Integer.MAX_VALUE;
    int maxLat = Integer.MIN_VALUE;
    int maxLong = Integer.MIN_VALUE;

    // check for null in case it is null
    if (nearPlaces.results != null) {


        // loop through all the places
        for (Place mplace : nearPlaces.results) {

            latitude = mplace.geometry.location.lat; // latitude
            longitude = mplace.geometry.location.lng; // longitude

            // Geopoint to place on map
            geoPoint = new GeoPoint((int) (latitude * 1E6),
                    (int) (longitude * 1E6));

            // Map overlay item
            overlayitem = new OverlayItem(geoPoint,p_u_name,mplace.reference);

            System.out.println("inside mymap:"+mplace.reference +p_u_name);

            itemizedOverlay.addOverlay(overlayitem);

            // calculating map boundary area
            minLat  = (int) Math.min( geoPoint.getLatitudeE6(), minLat );
            minLong = (int) Math.min( geoPoint.getLongitudeE6(), minLong);
            maxLat  = (int) Math.max( geoPoint.getLatitudeE6(), maxLat );
            maxLong = (int) Math.max( geoPoint.getLongitudeE6(), maxLong );
        }
        mapOverlays.add(itemizedOverlay);

        // showing all overlay items
        itemizedOverlay.populateNow();
    }


    // Adjusting the zoom level so that you can see all the markers on map
    mapView.getController().zoomToSpan(Math.abs( minLat - maxLat ), Math.abs( minLong - maxLong ));

    // Showing the center of the map
    mc.animateTo(new GeoPoint((maxLat + minLat)/2, (maxLong + minLong)/2 ));
    mapView.postInvalidate();
    }
    else
    {
         AlertDialog.Builder builder = new AlertDialog.Builder(MyPlacemapActivity.this);
           builder.setTitle("Connection Error.");
           builder.setMessage("Try again?.")  
                  .setCancelable(false)
                  .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                      public void onClick(DialogInterface dialog, int id) {
                          Intent u = new Intent(getApplicationContext(),Find_TabActivity.class);
                          startActivity(u);
                        dialog.dismiss();
                      }
                  });                     
           AlertDialog alert = builder.create();
           alert.show();    
    }
    }

    @Override
    protected boolean isRouteDisplayed() {
        return false;
    }

}
4

1 回答 1

2

问题出在这条线上:

finditemizedoverlay = new FindItemizedOverlay(drawable);

您正在初始化 aItemizedOverlay而没有传递onTap()创建AletDialo.

您应该将其替换为:

finditemizedoverlay = new FindItemizedOverlay(drawable, this);

Note:如果您将 logcat 放在您的问题中,它会有所帮助。

问候。

于 2012-11-24T13:35:28.577 回答