loading JSON with gson

Question

Trying to load a JSON file, getting an error but what does it mean?

   public class MovieCollection{
        private List<Movie> movies;
        private Movie movie;

        public MovieCollection() {

    this.movies = new ArrayList<Movie>();
} 

/**
 * Creates a new book collection with the specified list of books pre-defined.
 *
 * @param books A books list.
 */
public MovieCollection(List<Movie> movies) {
    this.movies= movies;
}

            public static MovieCollection loadFromJSONFile (File file){
                Gson gson = new Gson();
                JsonReader jsonReader = null;
                try {
                    jsonReader = new JsonReader(new FileReader(file));
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                    System.out.println("Error");
                }
                return gson.fromJson(jsonReader,  MovieCollection.class);
            }

Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2 path $

Answer 1

The error clearly says that the text you are trying to read is actually an array and not a JSON. It is an Array of JSON. This means you need some way of reading an array of objects like the one shown below:

Gson gson = new Gson(); 

User[] userArray = gson.fromJson(userJson, User[].class);  

This allows you to read array of User objects from a json array text. Sample json for above code is included below.

[
    {
      "name": "Alex",
      "id": 1
    },
    {
      "name": "Brian",
      "id": 2
    },
    {
      "name": "Charles",
      "id": 3
    }
]

User class is defined as

public class User 
{
    private long id;
    private String name;

    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + "]";
    }
}

Reference available at this link