JSON GSON.fromJson Java Objects

Question

I am trying to load my Json into my class

public User() {     this.fbId = 0;     this.email = "";     this.name = "";     this.thumb = "";     this.gender = "";     this.location = "";     this.relationship = null;     this.friends = new ArrayList(); } 

{     users:{         user:{             name:'the name',             email:'[email protected]',             friends:{                 user:{                     name:'another name',                     email:'[email protected]',                     friends:{                         user:{                             name:'yet another name',                             email:'[email protected]'                         }                     }                 }             }         }     } } 

I am struggling to get GSON to load the user details into the above Java object with the following code

User user = gson.fromJson(this.json, User.class); 

Answer 1

The JSON is invalid. A collection is not to be represented by {}. It stands for an object. A collection/array is to be represented by [] with commaseparated objects.

Here's how the JSON should look like:

{     users:[{         name: "name1",         email: "email1",         friends:[{             name: "name2",             email: "email2",             friends:[{                 name: "name3",                 email: "email3"             },             {                 name: "name4",                 email: "email4"             }]         }]     }] } 

(note that I added one more friend to the deepest nested friend, so that you understand how to specify multiple objects in a collection)

Given this JSON, your wrapper class should look like this:

public class Data {     private List<User> users;     // +getters/setters }  public class User {     private String name;     private String email;     private List<User> friends;     // +getters/setters } 

and then to convert it, use

Data data = gson.fromJson(this.json, Data.class); 

and to get the users, use

List<User> users = data.getUsers();