Java gson how to serialize List<Item> as list of objects in JSON string?

Question

I have a class Item like this

class Item {
   private String name;
   private int age;
   private boolean gender;
}

and a class which contains this Item class ListItem { private List items; }

When using gson to generate to JSON, it will return something like this

[{"name": "a", "age": "a1", "gender": "male"}, {"name": "b", "age": "b1", "gender": "female"}, ...]

but I want to customize (without changing the POJO class as I could not do this) and in method

List<Item> listItems = new ArrayList<Item>();
listItems.add(new Item("a", "a1", "male");
listItems.add(new Item("b", "b1", "female");

Gson gson = new Gson();
JsonElement jsonElement = gson.toJsonTree(listItems);

then jsonElement will generate in to JSON string a structure like this (list of objects and with "name": "object")

{ 
   "a": { "name": a, "age": "a1", "gender": "male" },
   "b": { "name": b, "age": "b1", "gender": "female"}
}

when I serialize it

String json = gson.toJson(jsonElement);

Bằng Rikimaru · Accepted Answer · 2017-01-05 12:37:25Z

1

Actually I can just change from

List<Item> to HashMap<String, Item>

then gson will generate this structure for me correctly.

answered Jan 5, 2017 at 12:37

Bằng Rikimaru

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