NullPointer with Primefaces GMap OverlaySelect event

Question

I have a problem with Primefaces whose version is 3.0.M3 . I used gmap and prime p:ajax.I wanted to do something is to get clicked Marker when a marker is clicked by a user on Gmap.

Here is the Code

<p:tabView effect="slide" effectDuration="normal" style="width:1050px;height:450px" >
            <p:tab title="blabla">
                <h:panelGrid colums="1">    
                </h:panelGrid>
            </p:tab>
            <p:tab title="blabla" >
                <h:panelGrid colums="1">
                    <h:form id="mapId">

                        <p:gmap  id="asd" center="39.000409,35.201554" 
                            zoom="#{mapBean.modelMap.zoomLevel}" 
                            type="ROADMAP" 
                            style="width:1000px;height:400px"
                            model="#{mapBean.emptyModel}"
                            widgetVar="map" >

                            <p:ajax event="overlaySelect" listener="#{mapBean.onMarkerSelect}"/>

                        </p:gmap>

                    </h:form>   
                </h:panelGrid>
            </p:tab></p:tabView>

and My ManagedBean

public void onMarkerSelect(OverlaySelectEvent event) {  

    Marker marker = (Marker) event.getOverlay();
    if (marker!=null) {
        System.out.println(marker.getId());
    }
    System.out.println("Clicked");
    modelMap.setZoomLevel(modelMap.getZoomLevel()+1);

}

Managed Bean Declarations

@ManagedBean(name="mapBean")
@RequestScoped
public class MapBean implements Serializable

I am taking NullPointerException in onMarkerSelect method.(event.getOverlay();)

Tried several primefaces version (all from 3.1 to 3.3) I have the same problem with all of them. — Simeon, Jun 06 '12 at 08:19

Simeon · Answer 1 · 2012-06-13T08:15:38.893

Fixed my problem.

The problem was that when the MapModel was created it was a local var:

public MapModel getModel() {

    final MapModel mapModel = new DefaultMapModel(); // this should be a field

    final Set<MapEventDto> events = service.loadEvents();
    for (MapEventDto event : events) {

        final double latitude = event.getLatitude().doubleValue();
        final double longitude = event.getLongitude().doubleValue();
        final String magnitude = event.getMagnitude().toString();

        final String title = "Id: " + event.getId() + ", Lat: " + latitude + ", Lng: " + longitude + ", Mag: " + magnitude;

        mapModel.addOverlay(new Marker(new LatLng(latitude, longitude), title));

    }
    return mapModel;
}

The whole mapModel could be garbage collected after the map is rendered (as it is no longer needed). So when the overlay event is called there would be no mapModel any more.

As soon as I made mapModel a field of the Bean the problem disappeared.

If someone else could also test this I'd be extremely grateful. — Simeon, Jun 06 '12 at 09:02
The general rule in JSF is that getters/setters should **not** do anything else than doing *just* the job they're named for: getting and setting a property. Preparing the data should be done in the (post)constructor or a (action)listener method or at highest lazy loading in the getter. See also http://stackoverflow.com/questions/2090033/why-jsf-calls-getters-multiple-times — BalusC, Jun 06 '12 at 12:42

score 3 · Answer 2 · edited Dec 10 '12 at 09:13

3

Use the static field as follows. It worked for me.

final static MapModel mapModel = new DefaultMapModel();

edited Dec 10 '12 at 09:13

888

3,246
8
41
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answered Dec 10 '12 at 08:48

gayan

39
1

As a rule of thumb, static fields should not represent state, as you pave the way for a lot of head aches. – Simeon Mar 11 '13 at 13:40

score 0 · Answer 3 · edited Aug 07 '13 at 22:15

0

final DefaultMapModel mapModel = new DefaultMapModel();

worked For as Global Variable,in viewScoped best vj

edited Aug 07 '13 at 22:15

Steve P.

14,489
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answered Aug 07 '13 at 21:54

vijayakumar gopalakrishnan

88
3
10

score 0 · Answer 4 · answered Oct 08 '13 at 18:43

Got through this and solved by changing scope for the Bean to ViewScoped instead of Request Scope, so it lasts during user activity.

No final/static declarators needed

  @ManagedBean(name="mapBean")
  @ViewScoped
  public class MapBean implements Serializable {  
    private MapModel draggableModel;   
    ...
  }

score 0 · Answer 5 · answered Jan 13 '14 at 16:16

0

Just change your bean scope to @SessionScoped or @ViewScoped so your bean won't be initialized for each request.

answered Jan 13 '14 at 16:16

gvieira

21
5

NullPointer with Primefaces GMap OverlaySelect event

5 Answers5