12

I'm getting this error when I receive only one single item in a list. I'm using Jersey in the server side REST Web service, I only get the error when the List returned one single element and when it has 0 elements I get java.lang.NullPointerException But when it has more than one it works perfectly, and this is how I'm doing it :

@GET
@Path("getproject")
@Produces(MediaType.APPLICATION_JSON)
public List<Project> getPagedProjects(
       @QueryParam("offset") int offset,
       @QueryParam("limit") int limit,
       @QueryParam("searchKey") String searchKey) throws Exception {

  System.out.println("Returning Paged Project ");
  return projectService.getPagedProjects(offset, limit, searchKey);
}

Why doesn't Jersey send a list that contains one single item? It is a bug in jersey? Is there a way to make it always serialize as an array?

This is my JSON data when the web service returns 0 element:

null

And This is my JSON data when web service returns 1 element :

{
    "project": {
        "abbreviation": "abc",
        "customer": "customer1",
        "description": "description3",
        "icon": "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",
        "name": "projectname3",
        "plannedEndDate": "2012-05-23T00:00:00+01:00",
        "plannedStartDate": "2012-05-23T00:00:00+01:00",
        "projectStatus": {
            "name": "In Progress"
        },
        "realEndDate": "2012-05-23T00:00:00+01:00",
        "realStartDate": "2012-05-23T00:00:00+01:00"
    }
}

And This is my JSON data when web service returns more than 1 element :

{
    "project": [
        {
            "abbreviation": "abd",
            "customer": "customer1",
            "description": "description1",
            "icon": "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",
            "name": "projectname1",
            "plannedEndDate": "2012-05-25T00:00:00+01:00",
            "plannedStartDate": "2012-05-23T00:00:00+01:00",
            "projectStatus": {
                "name": "Opened"
            },
            "realEndDate": "2012-05-25T00:00:00+01:00",
            "realStartDate": "2012-05-23T00:00:00+01:00"
        },
        {
            "abbreviation": "bd",
            "customer": "customer1",
            "description": "description2",
            "icon": "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",
            "name": "projectname2",
            "plannedEndDate": "2012-05-23T00:00:00+01:00",
            "plannedStartDate": "2012-05-23T00:00:00+01:00",
            "projectStatus": {
                "name": "Closed"
            },
            "realEndDate": "2012-05-23T00:00:00+01:00",
            "realStartDate": "2012-05-23T00:00:00+01:00"
        },
        {
            "abbreviation": "abc",
            "customer": "customer1",
            "description": "description3",
            "icon": "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",
            "name": "projectname3",
            "plannedEndDate": "2012-05-23T00:00:00+01:00",
            "plannedStartDate": "2012-05-23T00:00:00+01:00",
            "projectStatus": {
                "name": "In Progress"
            },
            "realEndDate": "2012-05-23T00:00:00+01:00",
            "realStartDate": "2012-05-23T00:00:00+01:00"
        }
    ]
}

And in android side I deserialize the JSON response like this :

Gson gson = new Gson();
final ProjectContainer container = gson.fromJson(resultat, ProjectContainer.class);
final ListView lv = (ListView) findViewById(R.id.list);
adaptateur = new ProjectAdapter(ProjectActivity.this, R.layout.ligne_project, container);
lv.setAdapter(adaptateur);

This is my ProjectContainer class :

  public class ProjectContainer {
        @SerializedName("project")
        List<Project> projects ;

        public List<Project> getProjects() {
            return projects;
        }    
        public void setProjects(List<Project> projects) {
            this.projects = projects;
        }
    }

I would greatly appreciate your help to solve this problem. Thanks in advance

Wijden
  • 511
  • 6
  • 11
  • 23
  • 1
    This might be related: [How to make Jersey/Jackson serialize empty list; single element list as an array](http://stackoverflow.com/questions/8214827/how-to-make-jersey-jackson-serialize-empty-list-single-element-list-as-an-array). – Paul Bellora May 20 '13 at 17:15
  • The question is quite unclear... You only get the error when the returned `List` as 1 element? When it has 0 or >1 elements it works? It'd be useful to wee the JSON response as well... – MikO May 20 '13 at 17:16
  • Yes I only get the error when the List returned one single element and when it has 0 elements I get java.lang.NullPointerException But when it has more than one it works perfectly. – Wijden May 20 '13 at 17:29
  • Could you provide the actual JSON responses the web service returns, if possible including de 3 different responses (0, 1 or >1 elements) – MikO May 20 '13 at 17:33
  • @MikO I updated my question as you request – Wijden May 20 '13 at 17:53

3 Answers3

14

Your issue results really weird for me... it seems that there must be some problem with Jersey's JSON serialization of single element arrays... if you Google "Jersey JSON single element arrays" you'll find the same issue, like here or here. I don't know too much about Jersey, so I can't help you with that...

That said, I can suggest a workaround using manually parsing in Gson, to adapt your parsing to the 2 different responses (object or array). You could do something like this:

//manually parsing until get the "project" element...
JsonParser parser = new JsonParser();
JsonObject rootObejct = parser.parse(yourJsonString).getAsJsonObject();
JsonElement projectElement = rootObejct.get("project");

Gson gson = new Gson();
List<Project> projectList = new ArrayList<>();

//Check if "project" element is an array or an object and parse accordingly...
if (projectElement.isJsonObject()) {
    //The returned list has only 1 element
    Project project = gson.fromJson(projectElement, Project.class);
    projectList.add(project);
}
else if (projectElement.isJsonArray()) {
    //The returned list has >1 elements
    Type projectListType = new TypeToken<List<Project>>() {}.getType();
    projectList = gson.fromJson(projectElement, projectListType);
}

//Now you have a List<Project> projectList with one or many Project elements, 
//depending on the response...

Note that you don't need your class ProjectContainer.

Something like this should work for you, although obviously the best thing would be fix the serialization issue!

Community
  • 1
  • 1
MikO
  • 18,243
  • 12
  • 77
  • 109
  • There's not a "problem" with Jersey or Gson ... the web service is basically broken and not returning consistently. His Java class has a `List` and that's what it has to be in the JSON (an array) if it's going to map properly. The web service is responding two different ways depending on the number of `Project` objects – Brian Roach May 21 '13 at 02:47
  • 1
    @Brian, obviously the web service is not responding correctly, that's for sure, but if the mapping to JSON is made by Jersey automatically... I guess there is indeed some "problem" (or strange behaviour) in Jersey mapping... Otherwise, where is the error, if he doesn't have any serialization code?! where is the service broken?! The problem must be in Jersey's serialization... – MikO May 21 '13 at 03:04
  • Oh wait, I see what you mean - I misread that. I thought you meant on the Gson side. Unknown - it depends on what `getPagedProjects` is returning. – Brian Roach May 21 '13 at 03:07
  • @Brian, yes in my answer I clearly said that the problem is with Jersey... and looking at the JSON responses the method `getPagedProjects` seems for me to be returning correctly, otherwise he wouldn't get that data... and it must be returning a `List` or even the IDE would be complaining... so, again, there is a problem with Jersey, and in the links I have provided they seem to have the same problem... – MikO May 21 '13 at 03:14
  • Thank you. I really appreciate you help @MikO, the links that you have provided are very helpful, I prefer fixing the serialization issue of Jersey more than working around with parsing in Gson. Thank you again I really appreciated your help. – Wijden May 21 '13 at 12:57
6

Basically, your web service is broken in terms of how it's replying. If there's only one object for project it's returning only an object instead of an array.

MikO's answer solves the problem but another approach is encapsulating that logic in a custom deserializer: 

class MyDeserializer implements JsonDeserializer<ProjectContainer> {

    @Override
    public ProjectContainer deserialize(JsonElement je, Type type, JsonDeserializationContext jdc) throws JsonParseException {

        JsonObject jo = je.getAsJsonObject().getAsJsonObject("project");
        if (jo.isJsonArray()) {
             return new Gson().fromJson(je, ProjectContainer.class);
        } else {
             Project p = jdc.deserialize(jo, Project.class);
             List<Project> pList = new ArrayList<Project>(1);
             pList.add(p);
             ProjectContainer pc = new ProjectContainer();
             pc.setProjects(pList);
             return pc;
        }
    }
}

Then you can use:

Gson gson = new GsonBuilder()
                .registerTypeAdapter(ProjectContainer.class, new MyDeserializer())
                .build();
ProjectContainer pContainer = gson.fromJson(myJson, ProjectContainer.class);
Brian Roach
  • 76,169
  • 12
  • 136
  • 161
0

I ended up using Jackson library instead of gson to parse the json response. It automatically converts object into ArrayList. It is pretty much similar to gson in terms of ease of use. Hope it helps!

Abhishek V
  • 12,488
  • 6
  • 51
  • 63