使用 gson 将 json 转换为 json 对象

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.

Answer 1

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.