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Error parsing JSON (MismatchedInputException)

I'm having problems parsing JSON, this is the error:
out of START_OBJECT token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.util.ArrayList<packagename....>` out of START_OBJECT token
And I know why it is happening I just don't know how to fix it. This JSON works:
{
"status_code": "SUCCESS",
"time": {
"date": "Mar 23, 2021 1:14:39 AM"
},
"info": [
{
"person": "2.2",
"role": "TEACHER"
},
{
"person": "2.3",
"role": "TEACHER"
}
]
}
This one does not:
{
"status_code": "SUCCESS",
"time": {
"date": "Mar 23, 2021 3:49:27 AM"
},
"info": {
"id": "1",
"person": [
{
"identifier": "John",
"role": "TEACHER"
},
{
"identifier": "Homer",
"role": "TEACHER"
},
{
"identifier": "Michael",
"role": "TEACHER"
},
{
"identifier": "Sarah",
"role": "TEACHER"
}
]
}
}
The problem seems to be the { character in front of the info field because with [ works. So this is the method I'm using to parse the JSON:
public Mono<PersonResponse> searchById(String id) {
return webClient.get().uri(id).retrieve().bodyToMono(PersonResponse.class);
}
Also tried:
public Mono<PersonResponse[]> searchById(String id) {
return webClient.get().uri(id).retrieve().bodyToMono(PersonResponse[].class);
}
Error right on line: 1, column: 1. Any suggestions of how to implement the method?
EDIT: Added classes.
PersonResponse:
public class PersonResponse implements Serializable{
private static final long serialVersionUID = 7506229887182440471L;
public String status_code;
public Timestamp time;
public List<PersonDetails> info;
public PersonResponse() {}
...getters / setters / toSting
PersonDetails:
public class PersonDetails implements Serializable{
private static final long serialVersionUID = 1294417456651475410L;
private int id;
private List<Person> person;
public PersonDetails(int version) {
super();
this.version = version;
}
...getters / setters / toSting
Person
public class Person implements Serializable{
private static final long serialVersionUID = 3290753964441709903L;
private String identifier;
private String role;
public Person(String identifier, String role) {
super();
this.identifier = identifier;
this.role = role;
}
...getters / setters / toSting

The problem isn't the JSON necessarily, it's that the JSON structure doesn't match your PersonResponse class. There's an info variable in PersonResponse that requires an array of what I assume to be persons, in the second example you're trying to push an object in there, which you can't. You have to either change your JSON, which you don't seem to want in this case, or the class you're trying to parse it to.
You need to restructure the info variable in PersonResponse to match the object you're trying to parse to it.

how to serialize a specific json format

I need to set json in a format provided below.
"Tyre": {
"title": "Tyre",
"cls": "TyreCondition",
"items": [
{
"firstItem": [
{
"title": "Front right tyre",
"value": "50%",
"subValue": "30,000 km Approx"
}
],
"secItem": [
{
"title": "title",
"value": "Front right tyre tread - 50%"
},
{
"title": "title",
"value": "Front right tyre tread - 50%"
}
]
}
]
}
class that i have created for this is looks like:
private String title;
private String cls;
#SerializedName("firstItem")
private List<UsedCarInspectionInfo> items;
#SerializedName("secItem")
private List<UsedCarTyreImage> imageList;
//getter and setter
when i run this code with this class structure, I am getting the json like-
"Tyre": {
"title": "Tyre",
"cls": "TyreCondition",
"firstItem": [
{
"title": "Front right tyre",
"value": "50%",
"subValue": "30,000 km Approx"
}
],
"secItem": [
{
"title": "title",
"value": "Front right tyre tread - 50%"
},
{
"title": "title",
"value": "Front right tyre tread - 50%"
}
]}
Any idea how i can get the firstItem and secItem array in Items array?

You get no items key in your JSON, because you override the items field in your Java class with #SerializedName.
You need something like this:
String title;
String cls;
List<Item> items;
static class Item {
List<FirstItem> firstItem;
List<SecItem> secItem;
}
static class FirstItem {
String title;
String value;
String subValue;
}
static class SecItem {
String title;
String value;
}

How can I convert a JSON string of objects into an ArrayList using Gson?

So I have a JSON string of countries like this:
{
"details": [
{
"country_id": "1",
"name": "Afghanistan",
"regions": null
},
{
"country_id": "2",
"name": "Albania",
"regions": null
},
{
"country_id": "3",
"name": "Algeria",
"regions": null
},
... and so on
}
Now I want to have a method that tries to convert this into an ArrayList of countries.
public static ArrayList<GFSCountry> get() {
return new Gson().fromJson(countriesJson, new TypeToken<ArrayList<GFSCountry>>(){}.getType());
}
But I get an
Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path
As per request, here is my GFSCountry class:
#SerializedName("country_id")
#Expose
private String countryId;
#SerializedName("name")
#Expose
private String name;
#SerializedName("regions")
#Expose
private Object regions;
public String getCountryId() {
return countryId;
}
public void setCountryId(String countryId) {
this.countryId = countryId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Object getRegions() {
return regions;
}
public void setRegions(Object regions) {
this.regions = regions;
}
I know I should adjust something either from the JSON string or the method. Any help?

Since the list is nested in your JSON you will need a small mapping class that contains the list.
Try
static class GFSCountryList {
public List<GFSCountry> details;
}
public static List<GFSCountry> get() {
return new Gson().fromJson(countriesJson, GFSCountryList.class).details;
}

It seems to me that Gson is expecting your json to be like this
[
{
"country_id": "1",
"name": "Afghanistan",
"regions": null
},
{
"country_id": "2",
"name": "Albania",
"regions": null
},
{
"country_id": "3",
"name": "Algeria",
"regions": null
},
... and so on
]
But it encounters an object (marked by { })
Either you have the possibility to change your json format, or you create a class with a "details" attribut as a list to be compatible with the json's format.

How to deserialize json with a string-url name-value pair

I have json response in the form
{
"total": 782,
"category": {
"id": 1120,
"name": "Computers & Programming"
},
"experts": [
{
"id": 385816,
"name": "Master Z",
"title": "Mr",
"description": " Expert in C++",
"profile": "http://...com/experts.svc/1.0/385816/..../json?.."
}
}
]
}
I am able to parse everything else in the experts[] array except "profile" whose value "http://...com/experts.svc/1.0/385816/..../json?.." has the following json response
{
"id": 385816,
"name": "Master Z",
"title": "",
"reviewsCount": 15359,
"averageRating": 4.87,
"status": 4,
"fee": 19.99,
"languages": "English",
"category": {
"id": 1120,
"name": "Computers & Programming"
}
}
The models used are as follows
1. main pojo:
public class ExpertObj
{
private String total;
private Category category;
private Experts[] experts;
}
Category pojo:
public class Category
{
private String id;
private String name;
}
3.Experts array pojo:
public class Experts
{
private String id;
private String name;
private String title;
private String description;
private String profile;
}
Am using Retrift 2.
private RestManager mManager;
List<Expert> mExperts = new ArrayList<>();
....
Call<ExpertsObj> call = mManager.getExpertsService().listAllExperts();
call.enqueue(new Callback<ExpertsObj>() {
#Override
public void onResponse(Call<ExpertsObj> call, Response<ExpertsObj> response) {
if (response.isSuccess()) {
ExpertsObj expertsObj = response.body();
mExperts = expertsObj.getExperts();
....}
At a loss how to parse the profile-url name-value pair and display the results in a detail layout in android.
Any help is appreciated.
New in android. Please excuse if anything is not explained properly.

How to extract the field using Gson

I am trying to use Gson to extract a field from a Json:
{ "attributes": { "538": { "id": "538", "code": "sabor", "label": "Sabor", "options": [ { "id": "24", "label": "Baunilha", "price": "0", "oldPrice": "0", "products": [ "1376" ] }, { "id": "25", "label": "Chocolate", "price": "0", "oldPrice": "0", "products": [ "1377" ] } ] } } }
What i need is the label field inside the options( in this case, Baunilha and Chocolate).
I tried with the following classes:
public class Customer implements Serializable{
#SerializedName("options")
private Produto options;
public Produto getOptions() {
return options;
}
public void setEmail(Produto options) {
this.options = options;
}
and
public class Produto implements Serializable{
#SerializedName("label")
private String label;
public String getLabel() {
return label;
}
public void setLabel(String label) {
this.label = label;
}
}
Customer cust = g.fromJson(ja, Customer.class);
But i keep getting null pointer errors.

the "options" value is not an object consisting of a string, the "options" value is an array of objects. You need to change your definition in Customer to be:
class CustomerWrapper {
#SerializedName("attributes")
private Map<String, Customer> attributes;
}
class Customer {
#SerializedName("options")
private List<Produto> options;
}