com.google.gson.internal.LinkedTreeMap cannot be cast to my class [duplicate]

Answer 1

use this when parsing

  public static <T> List<T> parseGsonArray(String json, Class<T[]> model) {
    return Arrays.asList(new Gson().fromJson(json, model));
}

Answer 2

If you use your own ArrayList<MyObject> in gson when parsing;

Type typeMyType = new TypeToken<ArrayList<MyObject>>(){}.getType();

ArrayList<MyObject> myObject = gson.fromJson(jsonString, typeMyType)

Answer 3

For JSON

{
    results: [
    {
        id: "10",
        phone: "+91783XXXX345",
        name: "Mr Example",
        email: "freaky@jolly.com"
    },
    {
        id: "11",
        phone: "+9178XXXX66",
        name: "Mr Foo",
        email: "freaky@jolly.com"
    }],
    statusCode: "1",
    count: "2"
}

In listView BaseAdapter file we need to map data using LinkedTreeMap Key Value object to get row attribute value as below:

...
...

    @Override
    public View getView(final int i, View view, ViewGroup viewGroup) {
        if(view==null)
        {
            view= LayoutInflater.from(c).inflate(R.layout.listview_manage_clients,viewGroup,false);
        }

        TextView mUserName = (TextView) view.findViewById(R.id.userName);
        TextView mUserPhone = (TextView) view.findViewById(R.id.userPhone);


        Object getrow = this.users.get(i);
        LinkedTreeMap<Object,Object> t = (LinkedTreeMap) getrow;
        String name = t.get("name").toString();

        mUserName.setText("Name is "+name);
        mUserPhone.setText("Phone is "+phone);

        return view;
    }
...
...

ListView from JSON Data using Retrofit2 in Android Example

Source Link

Answer 4

In my opinion, due to type erasure, the parser can't fetch the real type T at runtime. One workaround would be to provide the class type as parameter to the method.

Something like this works, there are certainly other possible workarounds but I find this one very clear and concise.

public static <T> List<T> stringToArray(String s, Class<T[]> clazz) {
    T[] arr = new Gson().fromJson(s, clazz);
    return Arrays.asList(arr); //or return Arrays.asList(new Gson().fromJson(s, clazz)); for a one-liner
}

And call it like:

String name = stringToArray(message, Product[].class).get(0).getName();

Answer 5

I also faced class cast exception of com.google.gson.internal.LinkedTreeMap for my signed build only. I added these below lines in progurard. Then it works fine.

-keepattributes Signature

-keepattributes Annotation

-keep class com.google.** { *; }

-keep class sun.misc.** { *; }

Answer 6

{"root": 
 [
  {"mBarcode":"123","mName":"Apfel","mPrice":"2.7"},
  {"mBarcode":"456","mName":"Pfirsich","mPrice":"1.1111"},
  {"mBarcode":"89325982","mName":"Birne","mPrice":"1.5555"}
 ]
} 


JsonObject root = g.fromJson(json, JsonObject.class);
//read root element which contains list
JsonElement e = root.get("root");
//as the element is array convert it 
JsonArray ja  = e.getAsJsonArray();

for(JsonElement j : ja){
   //here use the json to parse into your custom object 
}