Question

I have this JSON

{"A":"valA",
"B":["valB"],
"C":"valC",
"D":"valD",
"data":[{
    "data1":"dval1",
    "data2":"dval2",
    "data3":"dval3",
        "data4":"dval4",}],
"F":"valF"}

Java Object:

public class ABCDObject {
        private String A;
        private String B;
        private String C;
        private String D;
        private List<String> data = new ArrayList<String>(){
                {
                        add("data1");
                        add("data2");
                        add("data3");
                        add("data4");
                        }
                };
        private String F;

        //getters for the above A,B,C,D, and F 
                public List<String> getData() {
                return data;
        }

Main class

Gson gson = new Gson();
        ABCDObject abcdObj = gson.fromJson(response, ABCDObject.class);

I am trying to access value of C as

abcdObj.getC();

I am getting the error
com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected a string but was BEGIN_ARRAY at line 9 column 17

Another question is how to access the value of data–> data1 and so on

Answer 1

The JSON doesn’t match the object, including:

• B is an array in the JSON, and a String in ABCDObject
• data is an array of objects with four properties in the JSON, and an array of strings in ABCDObject.

---

Edit with example

Using the following two classes, and fixing the mal-formed JSON (the spurious comma after data4), this works as expected.

Data – holds each element of the “data” array, each data object has four data fields.

public class Data {
    private String data1;
    private String data2;
    private String data3;
    private String data4;
    // Plus getters, setters, toString
}

JsonHolder – encapsulates the entire JSON object.

import java.util.List;

public class JsonHolder {
    private String A;
    private List<String> B;
    private String C;
    private String D;
    private List<Data> data;
    private String F;
    // Plus getters, setters, toString
}

sanity check

public static void main(String[] args) {
    Gson gson = new Gson();
    JsonHolder json = gson.fromJson(JSON_STRING, JsonHolder.class);
    System.out.println(json);
}

output

JsonHolder{A='valA', B=[valB], C='valC', D='valD', data=[Data{data1='dval1', data2='dval2', data3='dval3', data4='dval4'}], F='valF'}

Note that attempting to work around the malformed JSON by using JsonReader.setLenient(true) won’t work in this case; it only handles extra commas at the end of an array (collection), not in an object itself as your example JSON contains.