How to convert JSON string into List of Java object?

Question

This is my JSON Array :-

[ 
    {
        "firstName" : "abc",
        "lastName" : "xyz"
    }, 
    {
        "firstName" : "pqr",
        "lastName" : "str"
    } 
]

I have this in my String object. Now I want to convert it into Java object and store it in List of java object. e.g. In Student object. I am using below code to convert it into List of Java object : -

ObjectMapper mapper = new ObjectMapper();
StudentList studentList = mapper.readValue(jsonString, StudentList.class);

My List class is:-

public class StudentList {

    private List<Student> participantList = new ArrayList<Student>();

    //getters and setters
}

My Student object is: -

class Student {

    String firstName;
    String lastName;

    //getters and setters
}

Am I missing something here? I am getting below exception: -

Exception : com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of com.aa.Student out of START_ARRAY token

Answer 1

You are asking Jackson to parse a StudentList. Tell it to parse a List (of students) instead. Since List is generic you will typically use a TypeReference

List<Student> participantJsonList = mapper.readValue(jsonString, new TypeReference<List<Student>>(){});

Answer 2

For any one who looks for answer yet:

1.Add jackson-databind library to your build tools like Gradle or Maven

2.in your Code:

ObjectMapper mapper = new ObjectMapper();

List<Student> studentList = new ArrayList<>();

studentList = Arrays.asList(mapper.readValue(jsonStringArray, Student[].class));

Answer 3

You can also use Gson for this scenario.

Gson gson = new Gson();
NameList nameList = gson.fromJson(data, NameList.class);

List<Name> list = nameList.getList();

Your NameList class could look like:

class NameList{
 List<Name> list;
 //getter and setter
}