What does the format from json into a list?

So basically I'm trying to remove some part of my list, but the problem is because I just got into android development, I don't know the format of the list that I got from JSON file. Here is the code of my method that retrieve it from a JSON file:

public void getCategory (JSONArray jsonArray, List<ModelCategory> Category){
    for (int i = 0; i < jsonArray.length(); i++){
        try {
            ModelCategory currentCategory = new ModelCategory();

            JSONObject jsonObject = jsonArray.getJSONObject(i);

            currentCategory.setCategoryID(jsonObject.getInt("idCategory"));
            currentCategory.setCategoryName(jsonObject.getString("name"));

            Category.add(currentCategory);
            kat1.addAll(Category);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Basically, I'm trying to remove the idCategory from the kat1 list. But I don't know what the list looks like. I've read about remove() method from the list, but how do I utilize the method to remove the idCategory? I'm sorry for the unclear title, I'm pretty new to java development.