Jackson error: no suitable constructor

Question

I'm using Jackson to deserialize a json array into some objects. Here's my class:

public class OfferContainer extends ActiveRecordBase{

    public Offer offer;

    public OfferContainer(){}

    public OfferContainer(Database db) {
        super(db);
    }

    @Override
    public String toString()
    {
        return this.getID() +  offer.toString();
    }

    public String getDescription() {
        return offer.description;
    }

    public String getBusinessName() {
        return offer.business.name;
    }



    public class Offer
    {
        public Category category;
        public String description;
        public String discount;
        public Date expiration;
        public Date published;
        public String rescinded_at;
        public String title;
        public String hook;
        public Date valid_from;
        public Date valid_to;
        public String id;
        public Business business;
        public Location location;
        public String image_270x155;

        public Offer() {
        }

        @Override
        public String toString()
        {
            return String.format(
                    "[Offer: category=%1$s, description=%2$s, discount=%3$s, expiration=%4$s, published=%5$s, rescinded_at=%6$s, title=%7$s, valid_from=%8$s, valid_to=%9$s, id=%10$s, business=%11$s, location=%12$s]",
                    category, description, discount, expiration, published, rescinded_at, title, valid_from, valid_to, id,
                    business, location);
        }

    }

   public enum Category
    {
        Salon, Spa, Restaurant, Other
    }

//    public class Category {
//        public String category;
//
//        public String toString() {
//            return String.format("[Category: category=%1$s]", category);
//        }
//    }


    public class Business
    {
        public String name;
        public String phone;
        public Address address;

        public Business(){}

        @Override
        public String toString()
        {
            return String.format(
                    "[Business: name=%1$s, phone=%2$s, address=%3$s]",
                    name, phone, address);
        }
    }


    public class Address
    {
        public String address_1;
        public String address_2;
        public String city;
        public String cross_streets;
        public String state;
        public String zip;

        public Address() {
        }

        @Override
        public String toString()
        {
            return String.format(
                    "[Address: address_1=%1$s, address_2=%2$s, city=%3$s, cross_streets=%4$s, state=%5$s, zip=%6$s]",
                    address_1, address_2, city, cross_streets, state, zip);
        }
    }

    public class Location {
        public double latitude;
        public double longitude;

        public Location() {
        }

        public String toString() {
            return String.format("[Location: longitude=%1$s, latitude=%2$s]", longitude, latitude);
        }

    }

}

And the error:

W/System.err(26911): org.codehaus.jackson.map.JsonMappingException: No suitable constructor found for type [simple type, class org.me.pojos.OfferContainer$Business]: can not instantiate from JSON object (need to add/enable type information?)
W/System.err(26911):  at [Source: java.io.StringReader@405fec40; line: 1, column: 382] (through reference chain: org.me.pojos.OfferContainer["offer"]->org.me.pojos.Offer["business"])
W/System.err(26911):    at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObjectUsingNonDefault(BeanDeserializer.java:740)
W/System.err(26911):    at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:683)
W/System.err(26911):    at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
W/System.err(26911):    at org.codehaus.jackson.map.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:299)
W/System.err(26911):    at org.codehaus.jackson.map.deser.SettableBeanProperty$FieldProperty.deserializeAndSet(SettableBeanProperty.java:579)
W/System.err(26911):    at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:635)
W/System.err(26911):    at org.codehaus.jackson.map.deser.SettableBeanProperty$InnerClassProperty.deserializeAndSet(SettableBeanProperty.java:780)
W/System.err(26911):    at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:697)
W/System.err(26911):    at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
W/System.err(26911):    at org.codehaus.jackson.map.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:104)
W/System.err(26911):    at org.codehaus.jackson.map.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:18)
W/System.err(26911):    at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2723)
W/System.err(26911):    at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1854)
W/System.err(26911):    at org.me.OffersUpdater.updateOffersIfNeeded(OffersUpdater.java:107)
W/System.err(26911):    at com.activities.Main$UpdateOffersTask.doInBackground(Main.java:265)
W/System.err(26911):    at com.activities.Main$UpdateOffersTask.doInBackground(Main.java:239)
W/System.err(26911):    at android.os.AsyncTask$2.call(AsyncTask.java:185)
W/System.err(26911):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
W/System.err(26911):    at java.util.concurrent.FutureTask.run(FutureTask.java:138)
W/System.err(26911):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
W/System.err(26911):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
W/System.err(26911):    at java.lang.Thread.run(Thread.java:1019)

I had been using GSON but need to abandon it on account of performance issues. When I switched to Jackson, I just added default constructors to all the classes, which was probably unnecessary because there were no other constructors defined...

EDIT: Oh, and the JSON looks like this:

  [ { "offer" : { "business" : { "address" : { "address_1" : "340 9th Avenue",
                "address_2" : null,
                "city" : "New York",
                "cross_streets" : null,
                "state" : "NY",
                "zip" : "10001"
              },
            "name" : "Blarney Stone",
            "phone" : "2125024656"
          },
        "category" : "Restaurant",
        "claim_link" : "http://m.thinknear.com/offers/BLARNEY__1323954754?app_id=kz4hjo&latitude=40.75042&longitude=-73.99633",
        "description" : "$1 off all drinks This discount was authorized by Toni Rossi. ",
        "discount" : null,
        "distance" : 161.40291744228713,
        "draws" : [ "American" ],
        "expiration" : "2011-12-15T21:59:59Z",
        "hook" : "$1 Off Drinks",
        "id" : "BLARNEY__1323954754",
        "image_270x155" : "https://s3.amazonaws.com/default_images/restaurant_stock_255x170.jpg",
        "location" : { "latitude" : "40.750444",
            "longitude" : "-73.99824579999999"
          },
        "mobile_claim_link" : "http://m.thinknear.com/offers/BLARNEY__1323954754?app_id=kz4hjo&latitude=40.75042&longitude=-73.99633",
        "published" : "2011-12-15T13:12:37Z",
        "rescinded_at" : null,
        "title" : "$1 Off All Drinks",
        "valid_from" : "2011-12-15T13:12:34Z",
        "valid_to" : "2011-12-15T21:29:59Z"
      } },
  { "offer" : { "business" : { "address" : { "address_1" : "252 W 31st St",
                "address_2" : null,
                "city" : "New York",
                "cross_streets" : null,
                "state" : "NY",
                "zip" : "10019"
              },
            "name" : "Hush Spa for Men",
            "phone" : "2127570508"
          },
        "category" : "Spa",
        "claim_link" : "http://m.thinknear.com/offers/HUSH_SPA_1323962075?app_id=kz4hjo&latitude=40.75042&longitude=-73.99633",
        "description" : "Use this offer now to enjoy this great Spa at a 30% discount. Applies to all services except massages. This discount was authorized by Andy Paningua. ",
        "discount" : "30",
        "distance" : 185.37847063528784,
        "draws" : [ "Body Work",
            "Facial",
            "Hair Removal"
          ],
        "expiration" : "2011-12-16T02:59:59Z",
        "hook" : "30% OFF",
        "id" : "HUSH_SPA_1323962075",
        "image_270x155" : "https://s3.amazonaws.com/ThinkNearMobileImages/hush_255x170.jpg",
        "location" : { "latitude" : "40.7499612",
            "longitude" : "-73.9942143"
          },
        "mobile_claim_link" : "http://m.thinknear.com/offers/HUSH_SPA_1323962075?app_id=kz4hjo&latitude=40.75042&longitude=-73.99633",
        "published" : "2011-12-15T15:14:36Z",
        "rescinded_at" : null,
        "title" : "30% off at Hush Spa for Men",
        "valid_from" : "2011-12-15T15:14:35Z",
        "valid_to" : "2011-12-16T02:29:59Z"
      } },
  { "offer" : { "business" : { "address" : { "address_1" : "481 8th Ave",
                "address_2" : "Ste 740 ",
                "city" : "New York",
                "cross_streets" : "34th  & 35th (New Yorker Hotel)",
                "state" : "NY",
                "zip" : "10001"
              },
            "name" : "Fusion Spa",
            "phone" : "+18325329272"
          },
        "category" : "Spa",
        "claim_link" : "http://m.thinknear.com/offers/FUSION_S_1323979416?app_id=kz4hjo&latitude=40.75042&longitude=-73.99633",
        "description" : "Use this offer now to enjoy this great Spa at a 20% discount. New customers only. Not valid with other offers. By appointment only. Call ahead for appointment. This discount was authorized by Tiffany Albert. ",
        "discount" : "20",
        "distance" : 350.0873566571568,
        "draws" : [ "Facial" ],
        "expiration" : "2011-12-16T01:59:59Z",
        "hook" : "20% OFF",
        "id" : "FUSION_S_1323979416",
        "image_270x155" : "https://s3.amazonaws.com/ThinkNearMobileImages/Fusion%2BSpa+1.jpg",
        "location" : { "latitude" : "40.7526135",
            "longitude" : "-73.99334859999999"
          },
        "mobile_claim_link" : "http://m.thinknear.com/offers/FUSION_S_1323979416?app_id=kz4hjo&latitude=40.75042&longitude=-73.99633",
        "published" : "2011-12-15T20:03:38Z",
        "rescinded_at" : null,
        "title" : "20% off at Fusion Spa",
        "valid_from" : "2011-12-15T20:03:36Z",
        "valid_to" : "2011-12-16T01:29:59Z"
      } }
]

Others have correctly pointed out that non-static inner classes are problematic. However, Jackson 1.9.0 does actually have some support for such classes -- so if you were using an earlier version, upgrade might have fixed things too. However, it is good practice to only use static inner classes if possible (to avoid overhead of passing the implicit parent reference around) — StaxMan, Dec 15 '11 at 23:54

score 65 · Accepted Answer · edited Jan 23 '14 at 21:09

65

I haven't worked with Jackson but I am guessing the issue is the Business class is a member class and not static.

What Jackson would need to do is

new OfferContainer.Business()

It cannot do this since it is a member class. Try making the class static.

public static class Business{ 
       ....
}

edited Jan 23 '14 at 21:09

Eran

387,369
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answered Dec 15 '11 at 20:54

John Vint

39,695
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1

Note that I had to make every inner class static. – LuxuryMode Dec 15 '11 at 21:37
Just wanted to chime in that I had this exact error and this was the cause. Making the inner class static fixed the problem. Yay, SO! – shoover Nov 08 '12 at 21:05
Thank you so much John.. Answer was really helpfull. – Suresh Aug 06 '13 at 14:09
Hi I am new to java, can you point out why I can not "new OfferContainer.Business()" if it is a (non-static) member class? Answered by myself: http://stackoverflow.com/questions/70324/java-inner-class-and-static-nested-class – Helin Wang Aug 10 '13 at 18:25
Because a non-static class instance must be associated to an object. In Jackson's case all it wants to do is create an instance of this class. To do so (in the OPs example) Jackson needs to create the Business class within an instance of an `OfferContainer`. Since there is no instance of OfferContainer it can create it in, Jackson cannot create a non-static member class of `Business`. – John Vint Aug 11 '13 at 20:49
The `Business` has an inferred `OfferContainer.this` reference that it can access as a member class. In a static context this is not possible (exactly what you want in Jackson's case) – John Vint Aug 11 '13 at 20:50
Just 2 cents from me: for Jackson you need to have an empty constructor for every POJO you use. So if you have some custom parametrized constructor implemented, don't forget to add an empty one also or you will get the same 'no suitable constructor' error – AAverin Nov 29 '13 at 04:52

score 4 · Answer 2 · answered Dec 15 '11 at 21:22

4

I wanted to accept an answer that someone posted before because it led me in the right direction. I made every member class static (and later had to add @JsonIgnoreProperties(ignoreUnknown = true) to one of them) and it works.

answered Dec 15 '11 at 21:22

LuxuryMode

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glad to see you got it working. I started going into the source and found nothing obvious – John Vint Dec 15 '11 at 21:24

Jackson error: no suitable constructor

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