How to serialize a convenient Json with a subcollection using Java?

Question

I'd like to build a json in ways of:

{"total":1,"rows":[{"id":1,"name":"Chai","price":18.00}],"footer":[{"name":"Total","price":18.00}]}

This example was obtained from: http://www.jeasyui.com/tutorial/datagrid/datagrid17.php

It's mandatory that I have a "total" property with some value and a "rows" property with a collection refering to it, exactly as in the example above.

Consider that for "rows" property actually I have a set of java Properties class objects, inside a List<Properties> collection, with value pairs for "id", "name" and "price".

Note: I'm using GSon (https://sites.google.com/site/gson/gson-user-guide) to stringify a set of properties, but I'm not achieving to correctly produce a valid json for that UI.

Code:

        Collection<Atividade> listProducts = storeService.getListPaged(category, rows, page);

        long qty = storeService.getTotal(category);

        List<Properties> lp = new LinkedList<Properties>();

        for (Item i : listProducts) {
            Properties prop = new Properties();

            prop.setProperty("id", Long.toString(i.getId()));
            prop.setProperty("name", i.getName());
            prop.setProperty("price", i.getPrice);
            lp.add(prop);
        }

        Object[][] array = {
            {"total",qty},
            {"rows", lp}
        };

        Gson gson = new GsonBuilder().setDateFormat("dd-MM-yyyy")
                .setPrettyPrinting().create();


        gList = gson.toJson(array);

This code produces the following result, instead of that from above:

[
  [
    "total",
    1
  ],
  [
    "rows",
    [
      {
        "id": "1",
        "name": "Chai",
        "price": "18.00",
      },
    ]
  ]
]

Thanks!

Answer 1

The JSON you are trying to generate

{"total":1,"rows":[{"id":1,"name":"Chai","price":18.00}],"footer":[{"name":"Total","price":18.00}]}

is a JSON object. As such, you can't use an array

Object[][] array = {
        {"total",qty},
        {"rows", lp}
};

to generate it.

Instead, create a POJO class with fields for each JSON name/value pair you want. One for total (which is a number), one for rows (which is an array/list of properties), and one for footer which is some other object).

You can then create an object, initialize its fields, and serialize it with Gson (or other JSON serializer).