GSON throwing Expected BEGIN OBJECT but was BEGIN ARRAY

Question

I m trying to parse a JSON string like this one                updated at   2012-03-02 21 06 01          fetched at   2012-03-02 21 28 37 728840          description  null         language  null         title   JOHN          url   http   rus JOHN JOHN rss php          icon url  null         logo url  null         id   4f4791da203d0c2d76000035          modified   2012-03-02 23 28 58 840076                    updated at   2012-03-02 14 07 44          fetched at   2012-03-02 21 28 37 033108          description  null         language  null         title   PETER          url   http   PETER PETER lv rss php          icon url  null         logo url  null         id   4f476f61203d0c2d89000253          modified   2012-03-02 23 28 57 928001           into a list of objects   List lt ChannelSearchEnum gt  lcs    List lt ChannelSearchEnum gt   new Gson   fromJson  jstring   ChannelSearchEnum class     Here s an object class I m using   import com google gson annotations SerializedName   public class ChannelSearchEnum       SerializedName  updated at   private String updated at    SerializedName  fetched at   private String fetched at    SerializedName  description   private String description    SerializedName  language   private String language    SerializedName  title   private String title    SerializedName  url   private String url    SerializedName  icon url   private String icon url    SerializedName  logo url   private String logo url    SerializedName  id   private String id    SerializedName  modified   private String modified   public final String get Updated at         return this updated at     public final String get Fetched at         return this fetched at     public final String get Description         return this description     public final String get Language         return this language     public final String get Title         return this title     public final String get Url         return this url     public final String get Icon url         return this icon url     public final String get Logo url         return this logo url     public final String get Id         return this id     public final String get Modified         return this modified                 But it throws me with  com google gson JsonSyntaxException  java lang IllegalStateException  Expected BEGIN OBJECT but was BEGIN ARRAY at line 1 column 2   Any ideas how should I fix it

User · Answer

I am not sure if this is the best way to use GSON, but works for me. You can use some like this on the MainActivity:

 public void readJson() {
    dataArrayList = new ArrayList<>();
    String json = "[\n" + IOHelper.getData(this) + "\n]\n";
    Log.d(TAG, json);
    try{
        JSONArray channelSearchEnums = new JSONArray(json);

        for(int i=0; i< channelSearchEnums.length(); i++)
        {
            JSONObject enum = channelSearchEnums.getJSONObject(i);
            ChannelSearchEnum channel = new ChannelSearchEnum(
                   enum.getString("updated_at"), enum.getString("fetched_at"),
                   enum.getString("description"), enum.getString("language"),
                   enum.getString("title"), enum.getString("url"),
                   enum.getString("icon_url"), enum.getString("logo_url"),
                   enum.getString("id"), enum.getString("modified"))         

                   dataArrayList.add(channel);
        }

         //The code and place you want to show your data            

    }catch (Exception e)
    {
        Log.d(TAG, e.getLocalizedMessage());
    }
}

You only have strings, but if you would have doubles or int, you could put getDouble or getInt too.

The method of IOHelper class is the next (Here, the path is save on the internal Storage):

 public static String getData(Context context) {
    try {
        File f = new File(context.getFilesDir().getPath() + "/" + fileName);
        //check whether file exists
        FileInputStream is = new FileInputStream(f);
        int size = is.available();
        byte[] buffer = new byte[size];
        is.read(buffer);
        is.close();
        return new String(buffer);
    } catch (IOException e) {
        Log.e("TAG", "Error in Reading: " + e.getLocalizedMessage());
        return null;
    }
}

If you want more information about this, you can see this video, where I get the code of readJson(); and this thread where I get the code of getData().

User · Answer

Solution  I am using volley library  I parse response automatic in volley using GSON                                        quot name quot    quot Naruto  Shippuuden quot                    quot description quot    quot It has been two and a half years since Naruto Uzumaki left Konohagakure  the Hidden Leaf Village  for intense training following events which fueled his desire to be stronger  Now Akatsuki  the mysterious organization of elite rogue ninja  is closing in on their grand plan which may threaten the safety of the entire shinobi world  quot                    quot Rating quot    quot 8 16 quot                    quot episode quot   500                   quot categorie quot   quot Animation   Drama   Adventure quot                    quot studio quot   quot Studio Pierrot quot                    quot img quot    quot https   myanimelist cdn-dena com images anime 5 17407 jpg quot                                                quot name quot    quot One Piece quot                    quot description quot    quot Gol D  Roger was known as the  Pirate King  the strongest and most infamous being to have sailed the Grand Line  The capture and death of Roger by the World Government brought a change throughout the world  His last words before his death revealed the existence of the greatest treasure in the world  One Piece  It was this revelation that brought about the Grand Age of Pirates  men who dreamed of finding One Piece   which promises an unlimited amount of riches and fame   and quite possibly the pinnacle of glory and the title of the Pirate King  quot                    quot Rating quot    quot 8 54 quot                    quot episode quot   700                    quot categorie quot   quot Animation   Drama   Adventure quot                    quot studio quot   quot Toei Animation quot                    quot img quot    quot https   myanimelist cdn-dena com images anime 6 73245 jpg quot                            2 This my model      public class DataResponse implements Serializable                 SerializedName  quot studio quot           private String studio                SerializedName  quot img quot           private String img                SerializedName  quot categorie quot           private String categorie                SerializedName  quot Rating quot           private String rating                SerializedName  quot name quot           private String name                SerializedName  quot description quot           private String description                SerializedName  quot episode quot           private int episode               public void setStudio String studio               this studio   studio                         public String getStudio                return studio                         public void setImg String img               this img   img                         public String getImg                return img                         public void setCategorie String categorie               this categorie   categorie                         public String getCategorie                return categorie                         public void setRating String rating               this rating   rating                         public String getRating                return rating                         public void setName String name               this name   name                         public String getName                return name                         public void setDescription String description               this description   description                         public String getDescription                return description                         public void setEpisode int episode               this episode   episode                         public int getEpisode                return episode                          Override         public String toString                return                   quot Response  quot                      quot studio     quot    studio                            quot  img     quot    img                            quot  categorie     quot    categorie                            quot  rating     quot    rating                            quot  name     quot    name                            quot  description     quot    description                            quot  episode     quot    episode                            quot   quot                          my api method  define globle  private List lt DataResponse gt  dataResponses   new ArrayList lt  gt            private void volleyAutomation String url                JSONArray array   new JSONArray                JsonArrayRequest request json   new JsonArrayRequest Request Method GET  url  array                      new Response Listener lt JSONArray gt                               Override                         public void onResponse JSONArray response                                     GsonBuilder gsonBuilder   new GsonBuilder                                Gson gson   gsonBuilder create                               dataResponses   Arrays asList gson fromJson response toString    DataResponse   class                                     rvList dataResponses                               Log d  quot respknce    quot   String valueOf dataResponses size                                                       new Response ErrorListener                      Override                 public void onErrorResponse VolleyError volleyError                                                       RequestQueue requestQueue   Volley newRequestQueue getApplicationContext                 requestQueue add request json

User · Answer

You need to let Gson know additional type of your response as below   import com google common reflect TypeToken  import java lang reflect Type    Type collectionType   new TypeToken lt List lt UserSite gt  gt      getType    List lt UserSite gt  userSites    gson fromJson  response getBody     collectionType

User · Answer

This looks like a Json array list Therefore its best to use ArrayList to handle the data  In your api end point add array list like this     GET  places    Call lt ArrayList lt Place gt  gt  getNearbyPlaces  Query  latitude   String latitude   Query  longitude   String longitude

User · Answer

Kotlin   var list ArrayList lt Your class name gt    val listresult  Array lt YOUR CLASS NAME gt    Gson   fromJson                  YOUR JSON RESPONSE IN STRING                  Array lt Your class name gt    class java   list addAll listresult

User · Answer

The problem is you re telling Gson you have an object of your type  You don t  You have an array of objects of your type  You can t just try and cast the result like that and expect it to magically work     The User guide for Gson Explains how to deal with this   https   github com google gson blob master UserGuide md  This will work   ChannelSearchEnum   enums   gson fromJson yourJson  ChannelSearchEnum   class     But this is better   Type collectionType   new TypeToken lt Collection lt ChannelSearchEnum gt  gt      getType    Collection lt ChannelSearchEnum gt  enums   gson fromJson yourJson  collectionType

User · Answer

The problem is that you are asking for an object of type ChannelSearchEnum but what you actually have is an object of type List lt ChannelSearchEnum gt     You can achieve this with   Type collectionType   new TypeToken lt List lt ChannelSearchEnum gt  gt      getType    List lt ChannelSearchEnum gt  lcs    List lt ChannelSearchEnum gt   new Gson                   fromJson  jstring   collectionType

User · Answer

Alternative could be  to make your response look like  myCustom JSONResponse    master                updated at   2012-03-02 21 06 01          fetched at   2012-03-02 21 28 37 728840          description  null         language  null         title   JOHN          url   http   rus JOHN JOHN rss php          icon url  null         logo url  null         id   4f4791da203d0c2d76000035          modified   2012-03-02 23 28 58 840076                    updated at   2012-03-02 14 07 44          fetched at   2012-03-02 21 28 37 033108          description  null         language  null         title   PETER          url   http   PETER PETER lv rss php          icon url  null         logo url  null         id   4f476f61203d0c2d89000253          modified   2012-03-02 23 28 57 928001             instead of   server JSONResponse                updated at   2012-03-02 21 06 01          fetched at   2012-03-02 21 28 37 728840          description  null         language  null         title   JOHN          url   http   rus JOHN JOHN rss php          icon url  null         logo url  null         id   4f4791da203d0c2d76000035          modified   2012-03-02 23 28 58 840076                    updated at   2012-03-02 14 07 44          fetched at   2012-03-02 21 28 37 033108          description  null         language  null         title   PETER          url   http   PETER PETER lv rss php          icon url  null         logo url  null         id   4f476f61203d0c2d89000253          modified   2012-03-02 23 28 57 928001           CODE    String server JSONResponse          the string in which you are getting your JSON Response after hitting URL String myCustom JSONResponse       in which we will keep our response after adding object element to it      MyClass apiResponse   new MyClass          myCustom JSONResponse     master     server JSONResponse             apiResponse   gson fromJson myCustom JSONResponse  MyClass  class     After this it will be just any other GSON Parsing

User · Answer

In my case JSON string      category   College Affordability      uid   150151      body   Ended more than  60 billion in wasteful subsidies for big banks and used the savings to put the cost of college within reach for more families       url   http     www whitehouse gov  economy  middle-class  helping middle-class-families-pay-for-college      url title   ending subsidies for student loan lenders      type   Progress      path   node  150385      and I print  category  and  url title  in recycleview  Datum class  import com google gson annotations Expose  import com google gson annotations SerializedName   public class Datum    SerializedName  category    Expose private String category   SerializedName  uid    Expose private String uid   SerializedName  url title    Expose private String urlTitle           return The category     public String getCategory         return category             param category The category     public void setCategory String category        this category   category             return The uid     public String getUid         return uid             param uid The uid     public void setUid String uid        this uid   uid             return The urlTitle     public String getUrlTitle         return urlTitle             param urlTitle The url title     public void setUrlTitle String urlTitle        this urlTitle   urlTitle         RequestInterface  import java util List   import retrofit2 Call  import retrofit2 http GET          Created by Shweta Chauhan on 13 07 16       public interface RequestInterface        GET  facts json progress all      Call lt List lt Datum gt  gt  getJSON        DataAdapter  import android content Context  import android support v7 widget RecyclerView  import android view LayoutInflater  import android view View  import android view ViewGroup  import android widget TextView   import java util ArrayList  import java util List          Created by Shweta Chauhan on 13 07 16       public class DataAdapter extends RecyclerView Adapter lt DataAdapter MyViewHolder gt    private Context context  private List lt Datum gt  dataList   public DataAdapter Context context  List lt Datum gt  dataList        this context   context      this dataList   dataList      Override public MyViewHolder onCreateViewHolder ViewGroup parent  int viewType        View view  LayoutInflater from parent getContext    inflate R layout data parent false       return new MyViewHolder view       Override public void onBindViewHolder MyViewHolder holder  int position        holder categoryTV setText dataList get position  getCategory         holder urltitleTV setText dataList get position  getUrlTitle          Override public int getItemCount         return dataList size       public class MyViewHolder extends RecyclerView ViewHolder       public TextView categoryTV  urltitleTV       public MyViewHolder View itemView            super itemView           categoryTV    TextView  itemView findViewById R id txt category           urltitleTV    TextView      itemView findViewById R id txt urltitle               and finally MainActivity java  import android support v7 app AppCompatActivity  import android os Bundle  import android support v7 widget LinearLayoutManager  import android support v7 widget RecyclerView  import android util Log  import java util ArrayList  import java util Arrays  import java util List   import retrofit2 Call  import retrofit2 Callback  import retrofit2 Response  import retrofit2 Retrofit  import retrofit2 converter gson GsonConverterFactory   public class MainActivity extends AppCompatActivity    private RecyclerView recyclerView  private DataAdapter dataAdapter  private List lt Datum gt  dataArrayList    Override protected void onCreate Bundle savedInstanceState        super onCreate savedInstanceState       setContentView R layout activity main       initViews       private void initViews        recyclerView  RecyclerView  findViewById R id recycler view       recyclerView setLayoutManager new LinearLayoutManager getApplicationContext          loadJSON       private void loadJSON        dataArrayList   new ArrayList lt  gt         Retrofit retrofit new Retrofit Builder   baseUrl  https   www whitehouse gov    addConverterFactory GsonConverterFactory create    build        RequestInterface requestInterface retrofit create RequestInterface class       Call lt List lt Datum gt  gt  call  requestInterface getJSON        call enqueue new Callback lt List lt Datum gt  gt               Override         public void onResponse Call lt List lt Datum gt  gt  call  Response lt List lt Datum gt  gt  response                dataArrayList   response body                dataAdapter new DataAdapter getApplicationContext   dataArrayList               recyclerView setAdapter dataAdapter                       Override         public void onFailure Call lt List lt Datum gt  gt  call  Throwable t                Log e  Error  t getMessage

User · Answer

public ChannelSearchEnum   getChannelSearchEnum Response response            return response as ChannelSearchEnum   class  ObjectMapperType GSON      Above will solve and passing response will returned mapped object array of the class

User · Answer

according to GSON User guide  you cannot   Collections Limitations Can serialize collection of arbitrary objects but can not deserialize from it  Because there is no way for the user to indicate the type of the resulting object

[java] GSON throwing "Expected BEGIN_OBJECT but was BEGIN_ARRAY"?

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