How to deserialize a list using GSON or another JSON library in Java?

Solution 1:

With Gson, you'd just need to do something like:

List<Video> videos = gson.fromJson(json, new TypeToken<List<Video>>(){}.getType());

You might also need to provide a no-arg constructor on the Video class you're deserializing to.

Solution 2:

Another way is to use an array as a type, e.g.:

Video[] videoArray = gson.fromJson(json, Video[].class);

This way you avoid all the hassle with the Type object, and if you really need a list you can always convert the array to a list, e.g.:

List<Video> videoList = Arrays.asList(videoArray);

IMHO this is much more readable.

In Kotlin this looks like this:

Gson().fromJson(jsonString, Array<Video>::class.java)

To convert this array into List, just use .toList() method

Solution 3:

I recomend this one-liner

List<Video> videos = Arrays.asList(new Gson().fromJson(json, Video[].class));

Warning: the list of videos, returned by Arrays.asList is immutable - you can't insert new values. If you need to modify it, wrap in new ArrayList<>(...).

Reference:

1. Method Arrays#asList
2. Constructor Gson
3. Method Gson#fromJson (source json may be of type JsonElement, Reader, or String)
4. Interface List
5. JLS - Arrays
6. JLS - Generic Interfaces