Java - Gson parse "Expected BEGIN_ARRAY but was BEGIN_OBJECT"

Question

I have a JSON similar to this which I get it by sending HTTP request.

{
      "0": {
        "name": "Chunk",
        "type": "magic",
        "item": "Chestplate",
        "item_min_lvl": "70",
        "id": {
          "health": "0.3",
          "spell": "24%",
          "life": "0.1",
          "xp": "24%",
          "loot": "22%"
        },
        "def": "67"
      },
      "1": {
        "name": "Thor",
        "type": "normal",
        "item": "Shoe",
        "item_min_lvl": "12",
        "id": {
          "xp": "24%"
        },
        "def": "12"
      },
      "2": {
        "name": "Clipper",
        "type": "normal",
        "item": "Sword",
        "item_min_lvl": "51",
        "id": {
          "health": "1",
          "life": "0.12",
          "xp": "4%"
        },
        "min_dam": "11",
        "max_dam": "7"
      }

}

Here is my code:

java.lang.reflect.Type type = new TypeToken<ArrayList<Map<String, Object>>>(){}.getType();
ArrayList<Map<String, Object>> list = gson.fromJson(json, type);//Error here
for(Map<String, Object> m : list)
{
    //blah
}

It returns this error Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2

Can anyone help me to solve this error? I am new to JSON and GSON. Please note, some of the the "items" aren't the same so I have to use TypeToken.

cghislai · Accepted Answer · 2014-08-06 11:31:55Z

1

You json does not include arrays (with syntax []) but objects (with syntax {}).

You probably need to use new TypeToken<Map<String, <Map<String, Object>>>>(){}.getType();

answered Aug 6, 2014 at 11:31

cghislai

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5 Comments

Jeremy Over a year ago

do I need to modify for(Map<String, Object> m : list) ?

cghislai Over a year ago

yes, but rather using for(Map<String, Object> m : list.values()) as list will be a Map<String, Map<String, Object>>

Jeremy Over a year ago

Uhh same error at this ` ArrayList<Map<String, Map<String, Object>>> list = gson.fromJson(json, type);`

cghislai Over a year ago

There is no array. java.lang.reflect.Type type = new TypeToken<Map<String, <Map<String, Object>>>>(){}.getType();Map<String, <Map<String, Object>>> map = gson.fromJson(json, type); for(Map<String, Object> m : map.values()) { /****/ } Also, Im not sure you need to specify the while type hierarchy using gson. Use JSonObject obj = gson.fromJson();

cghislai Over a year ago

If your json might differ, consider using JsonObject and adding checks to see if the property you want to read is actually a jsonobject. In other word, go down the object hierarchy manually.

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