How to convert custom object with map field that includes list of custom object to json? [duplicate]

Question

Let's say, I have an Employee class which looks like this:

public class Employee{

Map<String, ArrayList<Salary>> salary = new HashMap<String, ArrayList<Salary>>();
String name;
String age;
}

public class Salary{
String amount;
String currency;
}

What is the smartest way of convertion to/from Json in Java?

Or;

What if my json should look like that:

  {
  "name": "Test",
  "age": "12",
  "salary": {
    "first": {
      "41130": {
        "amount": "100",
        "currency": "€"
      },
      "41132": {
        "amount": "100",
        "currency": "€"
      }
    },
    "second": {
      "41129": {
        "amount": "100",
        "currency": "€"
      }
    }
  }
}

When i tried to convert this to Employee I am getting error below.

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT

Does it answer your question: stackoverflow.com/questions/15786129/… — Shredator
– Shredator, Commented Feb 18, 2020 at 6:34
Unfortunately doesn't. Maps, especially Map with an ArrayList in it more complex than just a List. — devmaria
– devmaria, Commented Feb 18, 2020 at 7:04
instaed of Map<String, ArrayList<Salary>> salary = new HashMap<String, ArrayList<Salary>>(); its better to implement on the in List interface: Map<String, List<Salary>> salary = new HashMap<String, ArrayList<Salary>>(); — Arthurofos
– Arthurofos, Commented Feb 18, 2020 at 9:33

Smile · Accepted Answer · 2020-02-18 10:38:25Z

1

public class Main {

    public static void main(String[] args) {

        Gson gson = new Gson();

        Map<String, ArrayList<Salary>> sal = new HashMap<String, ArrayList<Salary>>();
        ArrayList<Salary> salaries = new ArrayList<Salary>();
        Salary salary1 = new Salary("100", "€");
        Salary salary2 = new Salary("200", "€");
        salaries.add(salary1);
        salaries.add(salary2);
        sal.put("1", salaries);
        Employee employee = new Employee(sal, "Test", "12");

        System.out.println("Age -> " + employee.getAge());
        System.out.println("Name -> " + employee.getName());
        System.out.println("Salary -> " + employee.getSalary());

        String json = gson.toJson(employee);
        System.out.println("Json -> " + json);

        Employee employee1 = gson.fromJson(json, Employee.class);

        System.out.println("Age1 -> " + employee1.getAge());
        System.out.println("Name1 -> " + employee1.getName());
        System.out.println("Salary1 -> " + employee1.getSalary());
    }

    @Data
    @AllArgsConstructor
    @NoArgsConstructor
    public static class Employee{

        Map<String, ArrayList<Salary>> salary = new HashMap<String, ArrayList<Salary>>();
        String name;
        String age;
    }

    @Data
    @AllArgsConstructor
    @NoArgsConstructor
    public static class Salary{
        String amount;
        String currency;

    }
}

edited Feb 18, 2020 at 10:38

Smile

4,1484 gold badges30 silver badges44 bronze badges

answered Feb 18, 2020 at 9:30

Arthurofos

3082 silver badges12 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Arthurofos Over a year ago

import com.google.gson.Gson; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import java.util.ArrayList; import java.util.HashMap; import java.util.Map;

devmaria Over a year ago

It works wonderfull, thanks a million! I have last one question and edited the question up there. Would you look at that?

Victor Polo De Gyves Montero · Accepted Answer · 2020-02-18 06:34:10Z

0

Smartest way, if you plan to use that JSON on a web environment is to use Jackson, JAXB or anything your infraestructure already provides, e.g. Let your preferred REST infrastructure do the job for you.

You will need to provide more context on what is the purpose of your application or the required architecture.

answered Feb 18, 2020 at 6:34

Victor Polo De Gyves Montero

1,0981 gold badge9 silver badges17 bronze badges

Comments

TigerT · Accepted Answer · 2020-02-18 06:36:54Z

0

I think you can use Jackson ObjectMapper https://fasterxml.github.io/jackson-databind/javadoc/2.7/com/fasterxml/jackson/databind/ObjectMapper.html#writeValue(java.io.OutputStream,%20java.lang.Object)

ObjectMapper objectMapper = new ObjectMapper();
Employee employee = new Employee();
objectMapper.writeValue(new FileOutputStream("data/output.json"), employee);

answered Feb 18, 2020 at 6:36

TigerT

523 bronze badges

1 Comment

devmaria Over a year ago

This is not what i'm looking for. Returns wrong answer. But mapper.readTree() returned correct. However now I need to create Employee object from this JsonNode.

Collectives™ on Stack Overflow

How to convert custom object with map field that includes list of custom object to json? [duplicate]

3 Answers 3

2 Comments

Comments

1 Comment

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

1 Comment

Linked

Related