incorrect gson code: Expected BEGIN_OBJECT but was STRING

Question

I wrote code to parse response from server in json format. Here is the json

{
    "2FrontSide": {
        "back": ""
    },
    "3BackSide": {
        "back": ""
    },
    "4FrontSide": {
        "back": {
            "type": "image",
            "url": "http:\/\/www.abc.com\/sample_50.png"
        }
    }
}

and the code to parse this response is

Type collectionType = new TypeToken<Map<String,Map<String, VideosImages>>>(){}.getType();
Map<String,Map<String, VideosImages>> data = json.fromJson(resp, collectionType);

It gives

10-23 17:50:25.500: W/System.err(29598): com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 33
10-23 17:50:25.500: W/System.err(29598):    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:180)
10-23 17:50:25.500: W/System.err(29598):    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
10-23 17:50:25.505: W/System.err(29598):    at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:188)
10-23 17:50:25.505: W/System.err(29598):    at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:146)
10-23 17:50:25.505: W/System.err(29598):    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
10-23 17:50:25.505: W/System.err(29598):    at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:188)
10-23 17:50:25.505: W/System.err(29598):    at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:146)
10-23 17:50:25.510: W/System.err(29598):    at com.google.gson.Gson.fromJson(Gson.java:755)
10-23 17:50:25.510: W/System.err(29598):    at com.google.gson.Gson.fromJson(Gson.java:721)
10-23 17:50:25.510: W/System.err(29598):    at com.google.gson.Gson.fromJson(Gson.java:670)
10-23 17:50:25.515: W/System.err(29598):    at com.putitout.buck.helpers.Network.fetchAllVideosAndImages(Network.java:47)
10-23 17:50:25.515: W/System.err(29598):    at com.putitout.buck.VideoPlayback$2.run(VideoPlayback.java:462)
10-23 17:50:25.520: W/System.err(29598):    at java.lang.Thread.run(Thread.java:856)
10-23 17:50:25.520: W/System.err(29598): Caused by: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 33
10-23 17:50:25.525: W/System.err(29598):    at com.google.gson.stream.JsonReader.expect(JsonReader.java:339)
10-23 17:50:25.525: W/System.err(29598):    at com.google.gson.stream.JsonReader.beginObject(JsonReader.java:322)
10-23 17:50:25.530: W/System.err(29598):    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:168)
10-23 17:50:25.530: W/System.err(29598):    ... 12 more

Yahor10 · Accepted Answer · 2012-10-23 13:20:43Z

2

Implement InstanceCreator<Resp> and JsonDeserializer<Resp> to your resp and collection.

Register Type adapter in GsonBuilder

GsonBuilder builder = new GsonBuilder();
builder.registerTypeAdapter();

and Parse your json context in deserialize method.

    @Override
    public YourClass deserialize(JsonElement json, Type typeOfT,
            JsonDeserializationContext context){

}

edited Oct 23, 2012 at 13:20

answered Oct 23, 2012 at 13:03

Yahor10

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4 Comments

Ayaz Alavi Over a year ago

GsonBuilder is inside jar file. How do I register Type adapter there?

Ayaz Alavi Over a year ago

Resp is just a string, Should I implement these two interfaces at the class where I am using resp?

Yahor10 Over a year ago

No ,the just collection or your class VideoImages

zovits Over a year ago

"How do I register Type adapter there?" Look here: google-gson.googlecode.com/svn/trunk/gson/docs/javadocs/…

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