检查作为 JSONObject 数组的字符串是否为空

Question

So I am receiving, a jsonobject from an api call.

inside the jsonobject there is a field that can hold an array of JSONObjects

for example

{ "order":[]}

how can I check if the array is empty or not?

JSONSimple library

JSONObject[] check = new JSONObject[0];

JSONObject g = new JSONObject();
g.put("test", check);

System.out.println(((List<JSONObject>)g.get("test")).size());

Actual result: error

Desired result: size of json[]

Thanks

Answer 1

You cannot cast an array of JsonObject (JSONObject[]) to a List of JSONObject (List) - they are 2 different class with 2 different heirarchy. Cast it to JSONObject[], and since now it is an array and not a list, use length, not size().

    JSONObject[] check = new JSONObject[0];

    JSONObject g = new JSONObject();
    g.put("test", check);

    //System.out.println(((List<JSONObject>) g.get("test")).size());
    System.out.println(((JSONObject[]) g.get("test")).length);