Json Parsing with Lib Gson in Java - json

Question

I'm trying to parse this json captured through an API of my client:
[
{
"pagination": {
"page": 7,
"total_pages": 11,
"entries": 100,
"total_entries": 1007
},
"logical_numbers": [
{
"logical_number": {
"id": 50095,
"number": "524103650",
"app_version_ids": [
1427,
1230,
847
],
"created_by": 1510,
"created_via": "interface",
"group_id": 526,
"created_at": "2016-03-21T15:54:30.670-03:00",
"updated_at": "2016-03-21T15:54:30.682-03:00"
}
},
{
"logical_number": {
"id": 44593,
"number": "524103627",
"app_version_ids": [
1427,
1230,
847
],
"created_by": 1510,
"created_via": "interface",
"group_id": 526,
"created_at": "2016-02-26T10:02:20.561-03:00",
"updated_at": "2016-02-26T10:02:20.608-03:00"
}
}
]
}
]
Here are the classes I created for this work:
import java.io.FileReader;
import java.util.ArrayList;
import com.google.gson.Gson;
public class Test {
public static void main(String[] args) {
Gson gson = new Gson();
Pagination[] pagination = gson.fromJson(new FileReader("input1.json"), Pagination[].class);
System.out.println(gson.toJson(pagination));
}
}
class Pagination {
Long page;
Long total_pages;
Long entries;
Long total_entries;
ArrayList<LogicalNumbers> logicals;
}
class LogicalNumbers {
int id;
String number;
ArrayList<String> app_version_ids = new ArrayList<>();
String created_by;
String created_via;
String group_id;
String created_at;
String updated_at;
}
When I run this code, I get the following result:
[{}]
I'm not succeeding in the parsings. Can anybody help me?
Thanks.

Answer 1

After exploring the json I found the reason of the empty deseralization...
you have two small problems...
1st one:
your json is actually an array with one object that contains a Pagination
object and a logical numbers array
2nd: the POJO description of the json schema is not correct..
after a while I found a solution:
Try:
class Foo {
private Pagination pagination;
private List<LogicalNumbers> logical_numbers;
}
class Pagination {
Long page;
Long total_pages;
Long entries;
Long total_entries;
}
class LogicalNumbers {
Ln logical_number;
}
class Ln {
int id;
String number;
List<String> app_version_ids = new ArrayList<>();
String created_by;
String created_via;
String group_id;
String created_at;
String updated_at;
}
and then
public static void main(String[] args) {
Gson gson = new Gson();
Foo[] pagination = gson.fromJson(new FileReader("input1.json"), Foo[].class);
// Pagination[] pagination = gson.fromJson(new FileReader("input1.json"), Pagination[].class);
System.out.println(gson.toJson(pagination));
}