How to convert response to my class object?

Question

I am trying to convert response string into a java object (of Temp Class) for further manipulating but I get below error:

    Exception in thread "main" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 3 path $
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:226)
        at com.google.gson.Gson.fromJson(Gson.java:963)
        at com.google.gson.Gson.from

import com.google.gson.*;

class Temp {
    String name = "";
    int age = 0;
    String city = "";
}

class Scratch {
    public static void main(String[] args) {
        String response = " '{\"name\":\"John\", \"age\":30, \"city\":\"New York\"}' ";
    
        //convert response to Temp object
        Gson g = new Gson();

        Temp t = g.fromJson(response, Temp.class);
        System.out.println(t.age);
    }
}

response is already a JSON String. Why can't I convert it to Temp Class object?

Answer 1

There is error in the JSON Response itself. The response string includes extra spaces and single quotes, which is not the correct JSON format.

Consider the following corrected code.

import com.google.gson.*;

class Temp {
    String name = "";
    int age = 0;
    String city = "";
}

class Scratch {
    public static void main(String[] args) {
        String response = "{\"name\":\"John\", \"age\":30, \"city\":\"New York\"}";
    
        //convert response to Temp object
        Gson g = new Gson();

        Temp t = g.fromJson(response, Temp.class);
        System.out.println(t.age);
    }
}