parsing geojson using jackson

Question

I have some GeoJSON which corresponds to a PostGIS Point object.

Here is an example:

{"type":"Point","coordinates":[-397408.355686851020437,7575590.819041009992361]}

I tried to parse this into a postgis point object in Java by doing:

                ObjectMapper mapper = new ObjectMapper();
                Point coors = null;
                 try {
                     coors = mapper.readValue(str, Point.class);
                } catch (JsonParseException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (JsonMappingException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

I get the following JsonMappingException:

org.codehaus.jackson.map.JsonMappingException: Conflicting setter definitions for property "x": org.postgis.Point#setX(1 params) vs org.postgis.Point#setX(1 params)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._createAndCache2(StdDeserializerProvider.java:346)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._createAndCacheValueDeserializer(StdDeserializerProvider.java:321)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider.findValueDeserializer(StdDeserializerProvider.java:167)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider.findTypedValueDeserializer(StdDeserializerProvider.java:188)
    at org.codehaus.jackson.map.ObjectMapper._findRootDeserializer(ObjectMapper.java:2820)
    at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2719)
    at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1854)
    at dao.impl.PostGisDaoImpl.getOsmPoiNodes(PostGisDaoImpl.java:53)
    at service.OsmDBService.main(OsmDBService.java:24)
Caused by: java.lang.IllegalArgumentException: Conflicting setter definitions for property "x": org.postgis.Point#setX(1 params) vs org.postgis.Point#setX(1 params)
    at org.codehaus.jackson.map.introspect.POJOPropertyBuilder.getSetter(POJOPropertyBuilder.java:194)
    at org.codehaus.jackson.map.deser.BeanDeserializerFactory.addBeanProps(BeanDeserializerFactory.java:1065)
    at org.codehaus.jackson.map.deser.BeanDeserializerFactory.buildBeanDeserializer(BeanDeserializerFactory.java:654)
    at org.codehaus.jackson.map.deser.BeanDeserializerFactory.createBeanDeserializer(BeanDeserializerFactory.java:583)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._createDeserializer(StdDeserializerProvider.java:432)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._createAndCache2(StdDeserializerProvider.java:341)
    ... 8 more

Does anyone know what is wrong here? Thanks

EDIT:

New Exception:

org.codehaus.jackson.map.JsonMappingException: Conflicting setter definitions for property "x": org.postgis.Point#setX(1 params) vs org.postgis.Point#setX(1 params)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._createAndCache2(StdDeserializerProvider.java:346)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._createAndCacheValueDeserializer(StdDeserializerProvider.java:321)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider.findValueDeserializer(StdDeserializerProvider.java:167)
    at org.codehaus.jackson.map.deser.std.StdDeserializer.findDeserializer(StdDeserializer.java:596)
    at org.codehaus.jackson.map.deser.BeanDeserializer.resolve(BeanDeserializer.java:379)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._resolveDeserializer(StdDeserializerProvider.java:438)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._createAndCache2(StdDeserializerProvider.java:383)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._createAndCacheValueDeserializer(StdDeserializerProvider.java:321)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider.findValueDeserializer(StdDeserializerProvider.java:167)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider.findTypedValueDeserializer(StdDeserializerProvider.java:188)
    at org.codehaus.jackson.map.ObjectMapper._findRootDeserializer(ObjectMapper.java:2820)
    at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2719)
    at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1854)
    at dao.impl.PostGisDaoImpl.getOsmPoiNodes(PostGisDaoImpl.java:53)
    at service.OsmDBService.main(OsmDBService.java:24)
Caused by: java.lang.IllegalArgumentException: Conflicting setter definitions for property "x": org.postgis.Point#setX(1 params) vs org.postgis.Point#setX(1 params)
    at org.codehaus.jackson.map.introspect.POJOPropertyBuilder.getSetter(POJOPropertyBuilder.java:194)
    at org.codehaus.jackson.map.deser.BeanDeserializerFactory.addBeanProps(BeanDeserializerFactory.java:1065)
    at org.codehaus.jackson.map.deser.BeanDeserializerFactory.buildBeanDeserializer(BeanDeserializerFactory.java:654)
    at org.codehaus.jackson.map.deser.BeanDeserializerFactory.createBeanDeserializer(BeanDeserializerFactory.java:583)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._createDeserializer(StdDeserializerProvider.java:432)
    at org.codehaus.jackson.map.deser.StdDeserializerProvider._createAndCache2(StdDeserializerProvider.java:341)
    ... 14 more

Answer 1

The reason for the issue is that it sees both the definition of the variable an the setter method for the variable so double x; and setX(double x) as it being defined twice. You need to tell it to pick one or another by adding the @XmlAccessorType at the top of your class and setting it to XmlAccessType.FIELD or whichever you prefer it to use. For example:

@XmlAccessorType(XmlAccessType.FIELD)
public class Point {
  ...
}

---

If you are using Point from here it is different than what I expected. It is because it actually has two set methods: void setX(double x) and void setX(int x)

So in this case you want field access. Still looking to see how to set it programmatically instead of annotation.

UPDATE: I think in this case your best bet is to create a wrapper for the Point class that you can then pull the point back out of. So something like:

public class MyPoint {

    private String type;

    @JsonIgnore
    public Point point;

    public MyPoint(){
        this.point = new Point();
    }

    public double[] getCoordinates(){
        return new double[] {this.point.getX(), this.point.getY()};
    }

    public void setCoordinates(double[] x){
        if (x.length == 2){
            this.point.setX(x[0]);
            this.point.setY(x[1]);
        }
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

}

And then change your code to:

ObjectMapper mapper = new ObjectMapper();
Point coors = null;
 try {
     MyPoint mine = mapper.readValue(str, MyPoint.class);
     coors = mine.point;
} catch (JsonParseException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (JsonMappingException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

Maybe there is a better way, but this should work.

EDIT:

This is the test I ran to see if this worked:

public static void main(String[] args) {
    String str = "{\"type\":\"Point\",\"coordinates\":[-397408.355686851020437,7575590.819041009992361]}";

    ObjectMapper mapper = new ObjectMapper();
    Point coors = null;
     try {
         MyPoint mine = mapper.readValue(str, MyPoint.class);
         coors = mine.point;
    } catch (JsonParseException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (JsonMappingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
     System.out.println(coors);
}

And the output that I get:

POINT(-397408.355686851 7575590.81904101)

Answer 2

Exception points out the problem, which you can see from the Javadoc you linked to. There are two alternate setters:

void setX(double x)
void setX(int x) 

and Jackson doesn't want to guess which one it should try to use. Having a field and setter is NOT problematic; methods (setter) have precedence over fields.

Since you can't modify Point, you will probably want to use mix-in annotations. Or custom deerializer if you prefer.