parsing JSON array of JSON objects using Jackson throws JSON Mapping Exception, how to fix?

Question

This is my JSON :

    [
        {
           "_id": "574f1840d21303358a03d78b",
           "name": "Bank One of Kerala",
           "period_from": "2016-03-12T00:00:00.000Z",
           "period_to": "2016-03-12T00:00:00.000Z",
           "status": true,
           "ins": "Get an account at Bank One of Kerala :P",
           "fields": [
               {
                   "field": "Account Number",
                   "key": "acc"
               },
               {
                   "field": "IFSC",
                   "key": "ifsc"
               },
               {
                   "field": "Branch",
                   "key": "branch"
               },
               {
                   "field": "Name",
                   "key": "name"
               },
               {
                   "field": "PAN",
                   "key": "pan"
               }
          ]
    },
    {
        "_id": "574f18e4d21303358a03d78c",
        "name": "Bank Two of India",
        "period_from": "2016-03-12T00:00:00.000Z",
        "period_to": "2016-03-12T00:00:00.000Z",
        "status": true,
        "ins": "Get an account at Bank Two of India",
        "fields": [
            {
                "field": "Account Number",
                "key": "acc"
            },
            {
                "field": "IFSC",
                "key": "ifsc"
            },
            {
                "field": "Branch",
                "key": "branch"
            },
            {
                "field": "Name",
                "key": "name"
            }
    ]
  }
]

This is my model class:

ShreyPojo.class

    @JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({
        "_id",
        "name",
        "period_from",
        "period_to",
        "status",
        "ins",
        "fields"
})
public class ShreyPojo
{
    @JsonProperty("_id")
    private String id;
    @JsonProperty("name")
    private String name;
    @JsonProperty("period_from")
    private String periodFrom;
    @JsonProperty("period_to")
    private String periodTo;
    @JsonProperty("status")
    private Boolean status;
    @JsonProperty("ins")
    private String ins;
    @JsonProperty("fields")
    private List<Field> fields = new ArrayList<Field>();
    @JsonIgnore
    private Map<String, Object> additionalProperties = new HashMap<String, Object>();

    /**
     *
     * @return
     * The id
     */
    @JsonProperty("_id")
    public String getId() {
        return id;
    }

    /**
     *
     * @param id
     * The _id
     */
    @JsonProperty("_id")
    public void setId(String id) {
        this.id = id;
    }

    /**
     *
     * @return
     * The name
     */
    @JsonProperty("name")
    public String getName() {
        return name;
    }

    /**
     *
     * @param name
     * The name
     */
    @JsonProperty("name")
    public void setName(String name) {
        this.name = name;
    }

    /**
     *
     * @return
     * The periodFrom
     */
    @JsonProperty("period_from")
    public String getPeriodFrom() {
        return periodFrom;
    }

    /**
     *
     * @param periodFrom
     * The period_from
     */
    @JsonProperty("period_from")
    public void setPeriodFrom(String periodFrom) {
        this.periodFrom = periodFrom;
    }

    /**
     *
     * @return
     * The periodTo
     */
    @JsonProperty("period_to")
    public String getPeriodTo() {
        return periodTo;
    }

    /**
     *
     * @param periodTo
     * The period_to
     */
    @JsonProperty("period_to")
    public void setPeriodTo(String periodTo) {
        this.periodTo = periodTo;
    }

    /**
     *
     * @return
     * The status
     */
    @JsonProperty("status")
    public Boolean getStatus() {
        return status;
    }

    /**
     *
     * @param status
     * The status
     */
    @JsonProperty("status")
    public void setStatus(Boolean status) {
        this.status = status;
    }

    /**
     *
     * @return
     * The ins
     */
    @JsonProperty("ins")
    public String getIns() {
        return ins;
    }

    /**
     *
     * @param ins
     * The ins
     */
    @JsonProperty("ins")
    public void setIns(String ins) {
        this.ins = ins;
    }

    /**
     *
     * @return
     * The fields
     */
    @JsonProperty("fields")
    public List<Field> getFields() {
        return fields;
    }

    /**
     *
     * @param fields
     * The fields
     */
    @JsonProperty("fields")
    public void setFields(List<Field> fields) {
        this.fields = fields;
    }

    @JsonAnyGetter
    public Map<String, Object> getAdditionalProperties() {
        return this.additionalProperties;
    }

    @JsonAnySetter
    public void setAdditionalProperty(String name, Object value) {
        this.additionalProperties.put(name, value);
    }

}

Field.class

 @JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({
        "field",
        "key"
})

    public class Field
    {

        @JsonProperty("field")
        private String field;
        @JsonProperty("key")
        private String key;
        @JsonIgnore
        private Map<String, Object> additionalProperties = new HashMap<String, Object>();

        /**
         *
         * @return
         * The field
         */
        @JsonProperty("field")
        public String getField() {
            return field;
        }

        /**
         *
         * @param field
         * The field
         */
        @JsonProperty("field")
        public void setField(String field) {
            this.field = field;
        }

        /**
         *
         * @return
         * The key
         */
        @JsonProperty("key")
        public String getKey() {
            return key;
        }

        /**
         *
         * @param key
         * The key
         */
        @JsonProperty("key")
        public void setKey(String key) {
            this.key = key;
        }

        @JsonAnyGetter
        public Map<String, Object> getAdditionalProperties() {
            return this.additionalProperties;
        }

        @JsonAnySetter
        public void setAdditionalProperty(String name, Object value) {
            this.additionalProperties.put(name, value);
        }
    }

And, now when I try to parse the JSON,

 ShreyPojo obj = mapper.readValue(res,ShreyPojo.class); //res is the JSON string
 Log.w("JACKSON",""+obj.getName());

I get the exception :

    D/OkHttp: com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of com.shreybank.shrey.pojo.ShreyPojo out of START_ARRAY token
D/OkHttp:  at [Source: [{"_id":"574f1840d21303358a03d78b","name":"Bank One of Kerala","period_from":"2016-03-12T00:00:00.000Z","period_to":"2016-03-12T00:00:00.000Z","status":true,"ins":"Get an account at Bank One of Kerala :P","fields":[{"field":"Account Number","key":"acc"},{"field":"IFSC","key":"ifsc"},{"field":"Branch","key":"branch"},{"field":"Name","key":"name"},{"field":"PAN","key":"pan"}]},{"_id":"574f18e4d21303358a03d78c","name":"Bank Two of India","period_from":"2016-03-12T00:00:00.000Z","period_to":"2016-03-12T00:00:00.000Z","status":true,"ins":"Get an account at Bank Two of India","fields":[{"field":"Account Number","key":"acc"},{"field":"IFSC","key":"ifsc"},{"field":"Branch","key":"branch"},{"field":"Name","key":"name"}]}]; line: 1, column: 1]
D/OkHttp:     at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:873)
D/OkHttp:     at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:869)
D/OkHttp:     at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromArray(BeanDeserializerBase.java:1293)
D/OkHttp:     at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:159)
D/OkHttp:     at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:135)
D/OkHttp:     at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3789)
D/OkHttp:     at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2779)
D/OkHttp:     at com.shreybank.shrey.activities.BankDetailsActivity$1.onResponse(BankDetailsActivity.java:77)
D/OkHttp:     at okhttp3.RealCall$AsyncCall.execute(RealCall.java:133)
D/OkHttp:     at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
D/OkHttp:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
D/OkHttp:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
D/OkHttp:     at java.lang.Thread.run(Thread.java:818)

Since similar questions exist, I tried them in case I made a common mistake, since this one is not same, how to fix this?

Shaheen, res is JSONArray of JSONObject's, so you need to first get all JSONObject's from it in List then iterate it — ρяσѕρєя K
– ρяσѕρєя K, Commented Jun 3, 2016 at 5:38
Like List<ShreyPojo> listShreyPojo = objectMapper.readValue(res, new TypeReference<List<ShreyPojo>>() {}); — ρяσѕρєя K
– ρяσѕρєя K, Commented Jun 3, 2016 at 5:40
Please show update logs and code if still facing same issue. — ρяσѕρєя K
– ρяσѕρєя K, Commented Jun 3, 2016 at 6:15

Vickyexpert · Accepted Answer · 2016-06-03 06:21:14Z

2

Try below code.

 try {

       JSONArray  jsonArray = new JSONArray(res);
       List<ShreyPojo> pojoList = new ArrayList<>();

       for(int i = 0; i < jsonArray.length(); i++)
       {
          //JSONObject jsonObject = jsonArray.getJSONObject(i);
            String jsonObject = jsonArray.getString(i);

          ShreyPojo obj = mapper.readValue(jsonObject,ShreyPojo.class); 

           pojoList.add(obj);
       }

   // Use ShreyPojo objects as per requirement

 } catch (Exception e)
 {
    Log.w("Exception = ","" + e.toString());
 }

edited Jun 3, 2016 at 6:21

answered Jun 3, 2016 at 6:06

Vickyexpert

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4 Comments

OBX Over a year ago

ShreyPojo obj = mapper.readValue(jsonObject,ShreyPojo.class);

OBX Over a year ago

Getting error in this line : cannot resolve method 'readValue(org.json.JSONObject,java.lang.Class<ShreyPojo>)'

OBX Over a year ago

Thanks for helping out!

Vickyexpert Over a year ago

anytime enjoy your coding

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