convert json to json object using gson

Question

I have a class defined as follows -

public class info {
  private final string name;
  private final string add;
  private final Map<String, Skill> skills;
}

public class Skill {
  String subCategory;
  String proficiency;
}

JSON as  -
{
   "name": "abc",
   "add": "random",
   "skills": {
     "java": {
       "subCategory": "soft",
       "proficiency": "A"
     }
    "C#": {
       "subCategory": "soft",
       "proficiency": "B"
     }
  }
}

How can i convert this json to java object info? I have tried using gson library but running into multiple errors.

The issue is because of map inside a class skills. Not sure how to convert. i looked at example Converting JSON to Java object using Gson but its pretty simple no lists or map inside the class.

score 0 · Accepted Answer · answered Oct 29 '18 at 15:36

There are a few errors with your code, but after these are fixed it does work.

You're trying to define strings with string instead of String
You're defining your variables in info as final, and you're not defining them (removing the final keyword works)
You're missing a , in your skills array in your JSON

Below is an example which actually works:

public class Main {
    public static void main(String[] args) {
        String json = "{\r\n"
                + "   \"name\": \"abc\",\r\n"
                + "   \"add\": \"random\",\r\n"
                + "   \"skills\": {\r\n"
                + "     \"java\": {\r\n"
                + "       \"subCategory\": \"soft\",\r\n"
                + "       \"proficiency\": \"A\"\r\n"
                + "     },\r\n"
                + "    \"C#\": {\r\n"
                + "       \"subCategory\": \"soft\",\r\n"
                + "       \"proficiency\": \"B\"\r\n"
                + "     }\r\n"
                + "  }\r\n"
                + "}";

        Info info = new Gson().fromJson(json, Info.class);
        System.out.println(info.getSkills());
    }

}

class Info {
    private String name;
    private String add;
    private Map<String, Skill> skills;

    public String getName() {
        return this.name;
    }

    public String getAdd() {
        return this.add;
    }

    public Map<String, Skill> getSkills() {
        return this.skills;
    }
}

class Skill {
    String subCategory;
    String proficiency;
}

I've also taken the liberty to rename info to Info since class names should start with a capital letter & added getters for the private variables.

convert json to json object using gson

1 Answers1