Gson Array of Array Deserialization

Question

I've the following JSON structure:

[
 {
  "id": 1,
  "subcategories": [
   {
    "id": 2,
    "subcategories": [
    ]
   },
   {
    "id": 3,
    "subcategories": [
    ]
   }
  ]
 },
 {
  "id": 4,
  "subcategories": [
   {
    "id": 5,
    subcategories: [
    ]
   }
  ]
 }
]

The model class for a Category (some fields like title are omitted for simplicity), for reflecting JSON structure:

public class Category {
    int id = 0;
    ArrayList<Category> subCategories = null;
}

I'm trying to parse that with Gson library (2.2.4), having hard times deserializing inner array to arraylist:

Gson gson = new Gson();
Type collectionType = new TypeToken<ArrayList<Category>>(){}.getType();
ArrayList categories = gson.fromJson(json, collectionType);

Category.subCategories is always null.

Have you looked here? stackoverflow.com/questions/3763937/… — Tala
– Tala, Commented Aug 12, 2013 at 13:38
Ok, that works...I was missing Array to ArrayList conversion. — Jumpa
– Jumpa, Commented Aug 12, 2013 at 14:15
Great! Please answer question and accept your answeryourself so that it is marked answered — Tala
– Tala, Commented Aug 12, 2013 at 14:16

Jumpa · Accepted Answer · 2013-08-16 17:06:33Z

8

gson.fromJson(json, Category[].class)

worked good for me. If you want an ArrayList instead of an Array:

new ArrayList<Category>(Arrays.asList(gson.fromJson(json, Category[].class)));

edited Aug 16, 2013 at 17:06

answered Aug 12, 2013 at 14:38

Jumpa

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Comments

PrvN · Accepted Answer · 2013-08-12 14:17:13Z

-1

Try this.

public class Category {
    int id = 0;
    ArrayList<Category> subCategories = new ArrayList<Category>()
}

answered Aug 12, 2013 at 14:17

PrvN

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