Parsing JSON response in Retrofit

Question

I'm getting the following error when trying to parse JSON response with Retrofit: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $

This is what the JSON response looks like:

{
    "automobi": [{
        "Dealers": {
            "Dealer": [{
                "@attributes": {
                    "Id": "12",
                    "Name": "Barons Tokai",
                    "Region": "Western Cape",
                    "Status": "active",
                    "UniqueKey": "96ec67999ed613174efe17f697dc4695"
                }
            }, {
                "@attributes": {
                    "Id": "13",
                    "Name": "Barons Pietermaritzburg",
                    "Region": "KwaZulu-Natal",
                    "Status": "active",
                    "UniqueKey": "0f0637a035a9bc98ac67aa30ffc1367e"
                }
            }, {
                "@attributes": {
                    "Id": "36",
                    "Name": "Barons Bellville",
                    "Region": "Western Cape",
                    "Status": "active",
                    "UniqueKey": "9ec8f24fdee47f14ce56e9a3fc2689a4"
                }
            }, {
                "@attributes": {
                    "Id": "37",
                    "Name": "Barons Bruma",
                    "Region": "Gauteng",
                    "Status": "active",
                    "UniqueKey": "de7ac02f51463d94cb11947c1bf5589c"
                }
            }, {
                "@attributes": {
                    "Id": "38",
                    "Name": "Barons Culemborg",
                    "Region": "Western Cape",
                    "Status": "active",
                    "UniqueKey": "de2d98530d1ac95218c2eb5d25d847b2"
                }
            }, {
                "@attributes": {
                    "Id": "39",
                    "Name": "Barons N1 City",
                    "Region": "Western Cape",
                    "Status": "active",
                    "UniqueKey": "a055a9a6fa1c9a43cced2335ce6eefcb"
                }
            }, {
                "@attributes": {
                    "Id": "40",
                    "Name": "Barons Durban",
                    "Region": "KwaZulu-Natal",
                    "Status": "active",
                    "UniqueKey": "8e49cb3d88b54d144c6728a450b2f491"
                }
            }, {
                "@attributes": {
                    "Id": "41",
                    "Name": "Barons Woodmead",
                    "Region": "Gauteng",
                    "Status": "active",
                    "UniqueKey": "097722a842f43f0c59cfac14694b8443"
                }
            }]
        }
    }]
}

This is my Dealer class:

public class Dealer {
    @SerializedName("Id")
    String mId;

    @SerializedName("Name")
    String mName;

    @SerializedName("Region")
    String mRegion;

    @SerializedName("UniqueKey")
    String mUniqueKey;

    public String getId() {
        return mId;
    }

    public void setId(String id) {
        this.mId = id;
    }

    public String getName() {
        return mName;
    }

    public void setName(String name) {
        this.mName = name;
    }

    public String getRegion() {
        return mRegion;
    }

    public void setRegion(String region) {
        this.mRegion = region;
    }

    public String getUniqueKey() {
        return mUniqueKey;
    }

    public void setUniqueKey(String uniqueKey) {
        this.mUniqueKey = uniqueKey;
    }
}

This is the Retrofit call:

@FormUrlEncoded
@POST("get_dealer_list.php")
Call<List<Dealer>> getDealers(@Field("listname") String listName, @Field("outputformat") String outputFormat);

Any ideas for what I'm doing wrong?

Answer 1

1. Create below classes:

For the smallest child

"@attributes": { "Id": "12", "Name": "Barons Tokai", "Region": "Western Cape", "Status": "active", "UniqueKey": "96ec67999ed613174efe17f697dc4695" }

    public class DealerObject {
       @SerializedName("@attribute")
       Dealer attribute;

       public getAttribute() {
          return attribute;
       }
    }

For the next one

"Dealer": [ { "@attributes": { "Id": "12", "Name": "Barons Tokai", "Region": "Western Cape", "Status": "active", "UniqueKey": "96ec67999ed613174efe17f697dc4695" } }, { "@attributes": { "Id": "13", "Name": "Barons Pietermaritzburg", "Region": "KwaZulu-Natal", "Status": "active", "UniqueKey": "0f0637a035a9bc98ac67aa30ffc1367e" } }, { "@attributes": { "Id": "36", "Name": "Barons Bellville", "Region": "Western Cape", "Status": "active", "UniqueKey": "9ec8f24fdee47f14ce56e9a3fc2689a4" } }, { "@attributes": { "Id": "37", "Name": "Barons Bruma", "Region": "Gauteng", "Status": "active", "UniqueKey": "de7ac02f51463d94cb11947c1bf5589c" } }, { "@attributes": { "Id": "38", "Name": "Barons Culemborg", "Region": "Western Cape", "Status": "active", "UniqueKey": "de2d98530d1ac95218c2eb5d25d847b2" } }, { "@attributes": { "Id": "39", "Name": "Barons N1 City", "Region": "Western Cape", "Status": "active", "UniqueKey": "a055a9a6fa1c9a43cced2335ce6eefcb" } }, { "@attributes": { "Id": "40", "Name": "Barons Durban", "Region": "KwaZulu-Natal", "Status": "active", "UniqueKey": "8e49cb3d88b54d144c6728a450b2f491" } }, { "@attributes": { "Id": "41", "Name": "Barons Woodmead", "Region": "Gauteng", "Status": "active", "UniqueKey": "097722a842f43f0c59cfac14694b8443" } } ]

    public class DealerListObject {

       List<DealerObject> Dealer;

       public getDealer {
          return Dealer;
       }
    }

The Delers big object

"Dealers": { "Dealer": [ { "@attributes": { "Id": "12", "Name": "Barons Tokai", "Region": "Western Cape", "Status": "active", "UniqueKey": "96ec67999ed613174efe17f697dc4695" } }, { "@attributes": { "Id": "13", "Name": "Barons Pietermaritzburg", "Region": "KwaZulu-Natal", "Status": "active", "UniqueKey": "0f0637a035a9bc98ac67aa30ffc1367e" } }, { "@attributes": { "Id": "36", "Name": "Barons Bellville", "Region": "Western Cape", "Status": "active", "UniqueKey": "9ec8f24fdee47f14ce56e9a3fc2689a4" } }, { "@attributes": { "Id": "37", "Name": "Barons Bruma", "Region": "Gauteng", "Status": "active", "UniqueKey": "de7ac02f51463d94cb11947c1bf5589c" } }, { "@attributes": { "Id": "38", "Name": "Barons Culemborg", "Region": "Western Cape", "Status": "active", "UniqueKey": "de2d98530d1ac95218c2eb5d25d847b2" } }, { "@attributes": { "Id": "39", "Name": "Barons N1 City", "Region": "Western Cape", "Status": "active", "UniqueKey": "a055a9a6fa1c9a43cced2335ce6eefcb" } }, { "@attributes": { "Id": "40", "Name": "Barons Durban", "Region": "KwaZulu-Natal", "Status": "active", "UniqueKey": "8e49cb3d88b54d144c6728a450b2f491" } }, { "@attributes": { "Id": "41", "Name": "Barons Woodmead", "Region": "Gauteng", "Status": "active", "UniqueKey": "097722a842f43f0c59cfac14694b8443" } } ] }

   public class BigDealerObject {

       List<DealerListObject> Dealers;

       public getBigDealerObject {
          return Dealers;
       }
    }

Then for all the response:

   public class DealerResponse {

       List<BigDealerObject> automobi;

       public getAutomobi {
          return automobi;
       }
    }

Finally, call:

Call<DealerResponse> getDealers(@Field("listname") String listName, @Field("outputformat") String outputFormat);

Answer 2

Sure. As you can see your JSON response starts with an object ({}) while you are trying to assign that to a list (List). To solve this, you should create a class called something like Response which will have the following fields and classes inside:

public class Response {
    public DealersClass Dealers;
}

class DealersClass {
    public List<Dealer> Dealer;
}

Where the Dealer class is the class you have constructed. An easy way to avoid this kind of error in the future is to just take a look at your response. When you see { it means that you should match this to a Java class. When you see [ it means that you should match it to a Java List.

Hope it helps.