Parse JSON with dynamic key object inside dynamic key object with Gson

Question

I am a newbie to android and I have a JSON file with dynamic key like this:

{
  "x": {
    "a": {
      "1": [1,2,3,4],
      "2": [1,2,3,4]
    },
    "b": {
      "1": [1,2,3,4],
      "2": [1,2,3,4]
    }
  },
  "y": {
    "a": {
      "1": [1,2,3,4],
      "2": [1,2,3,4]
    },
    "b": {
      "1": [1,2,3,4],
      "2": [1,2,3,4]
    }
  },
  "z": {
    "a": {
      "1": [1,2,3,4],
      "2": [1,2,3,4]
    },
    "b": {
      "1": [1,2,3,4],
      "2": [1,2,3,4]
    }
  }
}

I parsed it successfully by JSONObject but I have to loop by keys Iterator on x, y, z. For each time, I have to loop on a, b and the same for "1" and "2". I think it's not a good solution. I created models for them like this:

Class XYZ {
private String name; // "x", "y", "z" value
private ArrayList<ABC> abcList;
}

Class ABC {
private String name; // "a", "b", "c"
private ArrayList<Item> itemList;
}

Class Item{
private String ID; // "1", "2"
private int[] valueArray;
}

Can anyone help me to parse this json by Gson, I think it looks more professional :D. Thank you so much

Welcome to stackoverflow. Please, provide relevant code for proving how far did you try and let other members where is you specific problem. — Kenzo_Gilead, Apr 29 '17 at 12:49
If keys dynamic the best choice I think convert to map. Type type = new TypeToken>(){}.getType(); Map myMap = gson.fromJson(jsonStringHere, type); And finally iterate over map key/values. — Maxim Tulupov, Apr 29 '17 at 13:18
Possible duplicate of [How to parse JSON in Java](http://stackoverflow.com/questions/2591098/how-to-parse-json-in-java) — Sahil Gulati, Apr 29 '17 at 14:41
Your JSON doesn't have `"name"` or `"ID"`key, so that Java model isn't correct — OneCricketeer, May 01 '17 at 18:27

score 0 · Accepted Answer · answered May 02 '17 at 17:54

Your models cannot map your JSON just because Gson default configuration clearly gets them unmatched.

You can have two "default" ways:

static

... since you didn't really mention why your JSON is considered dynamic:

final class XYZ {

    final ABC x = null;
    final ABC y = null;
    final ABC z = null;

}

final class ABC {

    final OneTwo a = null;
    final OneTwo b = null;

}

final class OneTwo {

    @SerializedName("1")
    final List<Integer> one = null;

    @SerializedName("2")
    final List<Integer> two = null;

}

Example:

try ( final Reader reader = getPackageResourceReader(Q43695739.class, "dynamic.json") ) {
    final XYZ xyz = gson.fromJson(reader, XYZ.class);
    System.out.println(xyz.x.b.two);
}

dynamic (by deserialization)

... assuming your keys are dynamic, but the structure remains the same:

private static final Type stringToStringToStringToIntegerListType = new TypeToken<Map<String, Map<String, Map<String, List<Integer>>>>>() {
}.getType();

try ( final Reader reader = getPackageResourceReader(Q43695739.class, "dynamic.json") ) {
    final Map<String, Map<String, Map<String, List<Integer>>>> m = gson.fromJson(reader, stringToStringToStringToIntegerListType);
    System.out.println(m.get("x").get("b").get("2"));
}

dynamic (by JSON trees)

Another true dynamic approach that may be helpful for some scenarios. Also note that JSONObject is not in the Gson realm: you probably might have imported this one from the org.json package. Gson uses camel-cased names like JsonElement, JsonObject, etc.

try ( final Reader reader = getPackageResourceReader(Q43695739.class, "dynamic.json") ) {
    final JsonElement jsonElement = gson.fromJson(reader, JsonElement.class)
            .getAsJsonObject()
            .getAsJsonObject("x")
            .getAsJsonObject("b")
            .getAsJsonArray("2");
    System.out.println(jsonElement);
}

The first and the second examples produce java.util.List instances

[1, 2, 3, 4]

The third example returns a JsonArray instance with a slightly different toString implementation:

[1,2,3,4]

Parse JSON with dynamic key object inside dynamic key object with Gson

1 Answers1

static

dynamic (by deserialization)

dynamic (by JSON trees)