How to convert JSON string into List of Java object?

Question

This is my JSON Array :-

[ 
    {
        \"firstName\" : \"abc\",
        \"lastName\" : \"xyz\"
    }, 
    {
        \"firstName\" : \"pqr\",
        \"         


        

Answer 1

For any one who looks for answer yet:

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

2.in your Codes:

 add:
               ObjectMapper mapper = new ObjectMapper();
               List<Student> studentList = new ArrayList<>();

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

Answer 2

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 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
}

Answer 4

Try this. It works with me. Hope you too!

List<YOUR_OBJECT> testList = new ArrayList<>();
testList.add(test1);

Gson gson = new Gson();

String json = gson.toJson(testList);

Type type = new TypeToken<ArrayList<YOUR_OBJECT>>(){}.getType();

ArrayList<YOUR_OBJECT> array = gson.fromJson(json, type);

Answer 5

I made a method to do this below called jsonArrayToObjectList. Its a handy static class that will take a filename and the file contains an array in JSON form.

 List<Items> items = jsonArrayToObjectList(
            "domain/ItemsArray.json",  Item.class);

    public static <T> List<T> jsonArrayToObjectList(String jsonFileName, Class<T> tClass) throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        final File file = ResourceUtils.getFile("classpath:" + jsonFileName);
        CollectionType listType = mapper.getTypeFactory()
            .constructCollectionType(ArrayList.class, tClass);
        List<T> ts = mapper.readValue(file, listType);
        return ts;
    }

Answer 6

I have resolved this one by creating the POJO class (Student.class) of the JSON and Main Class is used for read the values from the JSON in the problem.

   **Main Class**

    public static void main(String[] args) throws JsonParseException, 
       JsonMappingException, IOException {

    String jsonStr = "[ \r\n" + "    {\r\n" + "        \"firstName\" : \"abc\",\r\n"
            + "        \"lastName\" : \"xyz\"\r\n" + "    }, \r\n" + "    {\r\n"
            + "        \"firstName\" : \"pqr\",\r\n" + "        \"lastName\" : \"str\"\r\n" + "    } \r\n" + "]";

    ObjectMapper mapper = new ObjectMapper();

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

    for (Student itr : details) {

        System.out.println("Value for getFirstName is: " + 
                  itr.getFirstName());
        System.out.println("Value for getLastName  is: " + 
                 itr.getLastName());
    }
}

**RESULT:**
         Value for getFirstName is: abc
         Value for getLastName  is: xyz
         Value for getFirstName is: pqr
         Value for getLastName  is: str


 **Student.class:**

public class Student {
private String lastName;

private String firstName;

public String getLastName() {
    return lastName;
}

public String getFirstName() {
    return firstName;
} }